示例程序1

package demo;

import java.util.Vector;

class Cat {
    private int catNumber;

    Cat(int i) {
        catNumber = i;
    }

    void print() {
        System.out.println("Cat #" + catNumber);
    }
}

class Dog {
    private int dogNumber;

    Dog(int i) {
        dogNumber = i;
    }

    void print() {
        System.out.println("Dog #" + dogNumber);
    }
}

public class CatsAndDogs {
    public static void main(String[] args) {
        Vector cats = new Vector();
        for (int i = 0; i < 7; i++)
            cats.addElement(new Cat(i));
        cats.addElement(new Dog(7));
        for (int i = 0; i < 7; i++)
            ((Cat) cats.elementAt(i)).print();
        ((Dog) cats.elementAt(7)).print();
    }
}

import java.util.*;

 

public class Stacks {

static String[] months = { "1", "2", "3", "4" };

 

public static void main(String[] args) {

Stack stk = new Stack();

for (int i = 0; i < months.length; i++)

stk.push(months[i]);

System.out.println(stk);

System.out.println("element 2=" + stk.elementAt(2));

while (!stk.empty())

System.out.println(stk.pop());

}

}

package demo;

import java.util.*;

class Counter {
    int i = 1;
    //default：

    public String toString() {
        return Integer.toString(i);
    }
}

public class Statistics {
    public static void main(String[] args) {
        Hashtable ht = new Hashtable();
        for (int i = 0; i < 10000; i++) {
            Integer r = new Integer((int) (Math.random() * 20));
            //用Math.random()
            if (ht.containsKey(r))
                ((Counter) ht.get(r)).i++;
            else
                ht.put(r, new Counter());
            //输出r中数据的键值对出现的次数
        }
        System.out.println(ht);
    }
}

import java.util.*;

public class ArrayListDemo//ArrayList使用了数组的实现
{
    public static void main(String[] argv) {
        ArrayList al = new ArrayList();
        //在ArrayList中添加大量元素
        al.add(new Integer(11));
        al.add(new Integer(12));
        al.add(new Integer(13));
        al.add(new String("hello"));//下标从0开始，添加4个元素
        // First print them out using a for loop.
        System.out.println("Retrieving by index:");
        for (int i = 0; i < al.size(); i++) {
            System.out.println("Element " + i + " = " + al.get(i));
        }
    }
}

package linkedList;

import java.util.*;

/**
 * This program demonstrates operations on linked lists.
 * @version 1.11 2012-01-26
 * @author Cay Horstmann
 */
public class LinkedListTest
{
   public static void main(String[] args)
   {
      List<String> a = new LinkedList<>();
      a.add("Amy");
      a.add("Carl");
      a.add("Erica");

      List<String> b = new LinkedList<>();
      b.add("Bob");
      b.add("Doug");
      b.add("Frances");
      b.add("Gloria");

      // merge the words from b into a

      ListIterator<String> aIter = a.listIterator();
      Iterator<String> bIter = b.iterator();

      while (bIter.hasNext())
      {
         if (aIter.hasNext()) aIter.next();
         aIter.add(bIter.next());
      }

      System.out.println(a);

      // remove every second word from b

      bIter = b.iterator();
      while (bIter.hasNext())
      {
         bIter.next(); // skip one element
         if (bIter.hasNext())
         {
            bIter.next(); // skip next element
            bIter.remove(); // remove that element
         }
      }

      System.out.println(b);

      // bulk operation: remove all words in b from a

      a.removeAll(b);

      System.out.println(a);
   }
}

package set;

import java.util.*;

/**
 * This program uses a set to print all unique words in System.in.
 * @version 1.12 2015-06-21
 * @author Cay Horstmann
 */
public class SetTest
{
   public static void main(String[] args)
   {
      Set<String> words = new HashSet<>(); // HashSet implements Set
      long totalTime = 0;

      try (Scanner in = new Scanner(System.in))
      {
         while (in.hasNext())
         {
            String word = in.next();
            long callTime = System.currentTimeMillis();
            words.add(word);
            callTime = System.currentTimeMillis() - callTime;
            totalTime += callTime;
         }
      }

      Iterator<String> iter = words.iterator();
      for (int i = 1; i <= 20 && iter.hasNext(); i++)
         System.out.println(iter.next());
      System.out.println(". . .");
      System.out.println(words.size() + " distinct words. " + totalTime + " milliseconds.");
   }
}

package treeSet;

import java.util.*;

/**
 * An item with a description and a part number.
 */
public class Item implements Comparable<Item>
{
   private String description;
   private int partNumber;

   /**
    * Constructs an item.
    * 
    * @param aDescription
    *           the item''s description
    * @param aPartNumber
    *           the item''s part number
    */
   public Item(String aDescription, int aPartNumber)
   {
      description = aDescription;
      partNumber = aPartNumber;
   }

   /**
    * Gets the description of this item.
    * 
    * @return the description
    */
   public String getDescription()
   {
      return description;
   }

   public String toString()
   {
      return "[description=" + description + ", partNumber=" + partNumber + "]";
   }

   public boolean equals(Object otherObject)
   {
      if (this == otherObject) return true;
      if (otherObject == null) return false;
      if (getClass() != otherObject.getClass()) return false;
      Item other = (Item) otherObject;
      return Objects.equals(description, other.description) && partNumber == other.partNumber;
   }

   public int hashCode()
   {
      return Objects.hash(description, partNumber);
   }

   public int compareTo(Item other)
   {
      int diff = Integer.compare(partNumber, other.partNumber);
      return diff != 0 ? diff : description.compareTo(other.description);
   }
}

package treeSet;

import java.util.*;

/**
 * This program sorts a set of item by comparing their descriptions.
 * @version 1.12 2015-06-21
 * @author Cay Horstmann
 */
public class TreeSetTest
{
   public static void main(String[] args)
   {
      SortedSet<Item> parts = new TreeSet<>();
      parts.add(new Item("Toaster", 1234));
      parts.add(new Item("Widget", 4562));
      parts.add(new Item("Modem", 9912));
      System.out.println(parts);

      NavigableSet<Item> sortByDescription = new TreeSet<>(
            Comparator.comparing(Item::getDescription));

      sortByDescription.addAll(parts);
      System.out.println(sortByDescription);
   }
}

package map;

import java.util.*;

/**
 * This program demonstrates the use of a map with key type String and value type Employee.
 * @version 1.12 2015-06-21
 * @author Cay Horstmann
 */
public class MapTest
{
   public static void main(String[] args)
   {
      Map<String, Employee> staff = new HashMap<>();
      staff.put("144-25-5464", new Employee("Amy Lee"));
      staff.put("567-24-2546", new Employee("Harry Hacker"));
      staff.put("157-62-7935", new Employee("Gary Cooper"));
      staff.put("456-62-5527", new Employee("Francesca Cruz"));

      // print all entries

      System.out.println(staff);

      // remove an entry

      staff.remove("567-24-2546");

      // replace an entry

      staff.put("456-62-5527", new Employee("Francesca Miller"));

      // look up a value

      System.out.println(staff.get("157-62-7935"));

      // iterate through all entries

      staff.forEach((k, v) -> 
         System.out.println("key=" + k + ", value=" + v));
   }
}

package map;

import java.util.*;

/**
 * This program demonstrates the use of a map with key type String and value type Employee.
 * @version 1.12 2015-06-21
 * @author Cay Horstmann
 */
public class MapTest
{
   public static void main(String[] args)
   {
      Map<String, Employee> staff = new HashMap<>();
      staff.put("144-25-5464", new Employee("Amy Lee"));
      staff.put("567-24-2546", new Employee("Harry Hacker"));
      staff.put("157-62-7935", new Employee("Gary Cooper"));
      staff.put("456-62-5527", new Employee("Francesca Cruz"));

      // print all entries

      System.out.println(staff);

      // remove an entry

      staff.remove("567-24-2546");

      // replace an entry

      staff.put("456-62-5527", new Employee("Francesca Miller"));

      // look up a value

      System.out.println(staff.get("157-62-7935"));

      // iterate through all entries

      staff.forEach((k, v) -> 
         System.out.println("key=" + k + ", value=" + v));
   }
}

import java.io;
  2 import java.io.File;
  3 import java.io.FileInputStream;
  4 import java.io.FileNotFoundException;
  5 import java.io.IOException;
  6 import java.io.InputStreamReader;
  7 import java.util.ArrayList;
  8 import java.util.Arrays;
  9 import java.util.Collections;
 10 import java.util.Scanner;
 11 
 12 public class  Test{
 13     private static ArrayList<Student> studentlist;
 14     public static void main(String[] args) {
 15         studentlist = new ArrayList<>();
 16         Scanner scanner = new Scanner(System.in);
 17         File file = new File("C:\\下载\\身份证号.txt");
 18         try {
 19             FileInputStream fis = new FileInputStream(file);
 20             BufferedReader in = new BufferedReader(new InputStreamReader(fis));
 21             String temp = null;
 22             while ((temp = in.readLine()) != null) {
 23                 
 24                 Scanner linescanner = new Scanner(temp);
 25                 
 26                 linescanner.useDelimiter(" ");    
 27                 String name = linescanner.next();
 28                 String number = linescanner.next();
 29                 String sex = linescanner.next();
 30                 String age = linescanner.next();
 31                 String province =linescanner.nextLine();
 32                 Student student = new Student();
 33                 student.setName(name);
 34                 student.setnumber(number);
 35                 student.setsex(sex);
 36                 int a = Integer.parseInt(age);
 37                 student.setage(a);
 38                 student.setprovince(province);
 39                 studentlist.add(student);
 40 
 41             }
 42         } catch (FileNotFoundException e) {
 43             System.out.println("学生信息文件找不到");
 44             e.printStackTrace();
 45         } catch (IOException e) {
 46             System.out.println("学生信息文件读取错误");
 47             e.printStackTrace();
 48         }
 49         boolean isTrue = true;
 50         while (isTrue) {
 51             System.out.println("选择你的操作，输入正确格式的选项");
 52             System.out.println("1.按姓名字典序输出人员信息");
 53             System.out.println("2.输出年龄最大和年龄最小的人");
 54             System.out.println("3.查找老乡");
 55             System.out.println("4.查找年龄相近的人");
 56             System.out.println("5.退出");
 57             String m = scanner.next();
 58             switch (m) {
 59             case "1":
 60                 Collections.sort(studentlist);              
 61                 System.out.println(studentlist.toString());
 62                 break;
 63             case "2":
 64                  int max=0,min=100;
 65                  int j,k1 = 0,k2=0;
 66                  for(int i=1;i<studentlist.size();i++)
 67                  {
 68                      j=studentlist.get(i).getage();
 69                  if(j>max)
 70                  {
 71                      max=j; 
 72                      k1=i;
 73                  }
 74                  if(j<min)
 75                  {
 76                    min=j; 
 77                    k2=i;
 78                  }
 79                  
 80                  }  
 81                  System.out.println("年龄最大："+studentlist.get(k1));
 82                  System.out.println("年龄最小："+studentlist.get(k2));
 83                 break;
 84             case "3":
 85                  System.out.println("输入省份");
 86                  String find = scanner.next();        
 87                  String place=find.substring(0,3);
 88                  for (int i = 0; i <studentlist.size(); i++) 
 89                  {
 90                      if(studentlist.get(i).getprovince().substring(1,4).equals(place)) 
 91                          System.out.println("老乡"+studentlist.get(i));
 92                  }             
 93                  break;
 94                  
 95             case "4":
 96                 System.out.println("年龄：");
 97                 int yourage = scanner.nextInt();
 98                 int near=agenear(yourage);
 99                 int value=yourage-studentlist.get(near).getage();
100                 System.out.println(""+studentlist.get(near));
101                 break;
102             case "5":
103                 isTrue = false;
104                 System.out.println("退出程序!");
105                 break;
106                 default:
107                 System.out.println("输入有误");
108 
109             }
110         }
111     }
112         public static int agenear(int age) {      
113         int j=0,min=53,value=0,k=0;
114          for (int i = 0; i < studentlist.size(); i++)
115          {
116              value=studentlist.get(i).getage()-age;
117              if(value<0) value=-value; 
118              if (value<min) 
119              {
120                 min=value;
121                 k=i;
122              } 
123           }    
124          return k;         
125       }
126 
127 }

public class Student implements Comparable<Student> {
 2 
 3     private String name;
 4     private String number ;
 5     private String sex ;
 6     private int age;
 7     private String province;
 8    
 9     public String getName() {
10         return name;
11     }
12     public void setName(String name) {
13         this.name = name;
14     }
15     public String getnumber() {
16         return number;
17     }
18     public void setnumber(String number) {
19         this.number = number;
20     }
21     public String getsex() {
22         return sex ;
23     }
24     public void setsex(String sex ) {
25         this.sex =sex ;
26     }
27     public int getage() {
28 
29         return age;
30         }
31         public void setage(int age) {
32             // int a = Integer.parseInt(age);
33         this.age= age;
34         }
35 
36     public String getprovince() {
37         return province;
38     }
39     public void setprovince(String province) {
40         this.province=province ;
41     }
42 
43     public int compareTo(Student o) {
44        return this.name.compareTo(o.getName());
45     }
46 
47     public String toString() {
48         return  name+"\t"+sex+"\t"+age+"\t"+number+"\t"+province+"\n";
49     }    
50 }

package 运算;

import java.util.Scanner;

public class Demo {
	public static void main(String[] args) {
	// 用户的答案要从键盘输入，因此需要一个键盘输入流
@SuppressWarnings("resource")
	Scanner in = new Scanner(System.in);
	// 定义一个变量用来统计得分
int sum = 0;
	// 通过循环生成10道题
for (int i = 0; i < 10; i++) {

// 随机生成两个10以内的随机数作为被除数和除数
int a = (int) Math.round(Math.random() * 10);
	int b = (int) Math.round(Math.random() * 10);
	System.out.println(a + "/" + b + "=");
	// 定义一个整数用来接收用户输入的答案
int c = in.nextInt();
	// 判断用户输入的答案是否正确，正确给10分，错误不给分
if (c == a / b) {
	sum += 10;
	System.out.println("恭喜答案正确");
	}
else {
	System.out.println("抱歉，答案错误");
	}
	}
	//输出用户的成绩
System.out.println("你的得分为"+sum);
	}
}

package 运算;

public class Yuns {
	public int add(int a,int b)
 {
 return a+b;
 }
 public int reduce(int a,int b)
 {
 if((a-b)>0)
 return a-b;
 else return 0;
 }
 public int multiply(int a,int b)
 {
 return a*b;
 }
 public int devision(int a,int b)
 {
 if(b!=0)
 return a/b;
 else return 0;

 }

import java.io;
  2 import java.io.File;
  3 import java.io.FileInputStream;
  4 import java.io.FileNotFoundException;
  5 import java.io.IOException;
  6 import java.io.InputStreamReader;
  7 import java.util.ArrayList;
  8 import java.util.Arrays;
  9 import java.util.Collections;
 10 import java.util.Scanner;
 11 
 12 public class  Test{
 13     private static ArrayList<Student> studentlist;
 14     public static void main(String[] args) {
 15         studentlist = new ArrayList<>();
 16         Scanner scanner = new Scanner(System.in);
 17         File file = new File("C:\\下载\\身份证号.txt");
 18         try {
 19             FileInputStream fis = new FileInputStream(file);
 20             BufferedReader in = new BufferedReader(new InputStreamReader(fis));
 21             String temp = null;
 22             while ((temp = in.readLine()) != null) {
 23                 
 24                 Scanner linescanner = new Scanner(temp);
 25                 
 26                 linescanner.useDelimiter(" ");    
 27                 String name = linescanner.next();
 28                 String number = linescanner.next();
 29                 String sex = linescanner.next();
 30                 String age = linescanner.next();
 31                 String province =linescanner.nextLine();
 32                 Student student = new Student();
 33                 student.setName(name);
 34                 student.setnumber(number);
 35                 student.setsex(sex);
 36                 int a = Integer.parseInt(age);
 37                 student.setage(a);
 38                 student.setprovince(province);
 39                 studentlist.add(student);
 40 
 41             }
 42         } catch (FileNotFoundException e) {
 43             System.out.println("学生信息文件找不到");
 44             e.printStackTrace();
 45         } catch (IOException e) {
 46             System.out.println("学生信息文件读取错误");
 47             e.printStackTrace();
 48         }
 49         boolean isTrue = true;
 50         while (isTrue) {
 51             System.out.println("选择你的操作，输入正确格式的选项");
 52             System.out.println("1.按姓名字典序输出人员信息");
 53             System.out.println("2.输出年龄最大和年龄最小的人");
 54             System.out.println("3.查找老乡");
 55             System.out.println("4.查找年龄相近的人");
 56             System.out.println("5.退出");
 57             String m = scanner.next();
 58             switch (m) {
 59             case "1":
 60                 Collections.sort(studentlist);              
 61                 System.out.println(studentlist.toString());
 62                 break;
 63             case "2":
 64                  int max=0,min=100;
 65                  int j,k1 = 0,k2=0;
 66                  for(int i=1;i<studentlist.size();i++)
 67                  {
 68                      j=studentlist.get(i).getage();
 69                  if(j>max)
 70                  {
 71                      max=j; 
 72                      k1=i;
 73                  }
 74                  if(j<min)
 75                  {
 76                    min=j; 
 77                    k2=i;
 78                  }
 79                  
 80                  }  
 81                  System.out.println("年龄最大："+studentlist.get(k1));
 82                  System.out.println("年龄最小："+studentlist.get(k2));
 83                 break;
 84             case "3":
 85                  System.out.println("输入省份");
 86                  String find = scanner.next();        
 87                  String place=find.substring(0,3);
 88                  for (int i = 0; i <studentlist.size(); i++) 
 89                  {
 90                      if(studentlist.get(i).getprovince().substring(1,4).equals(place)) 
 91                          System.out.println("老乡"+studentlist.get(i));
 92                  }             
 93                  break;
 94                  
 95             case "4":
 96                 System.out.println("年龄：");
 97                 int yourage = scanner.nextInt();
 98                 int near=agenear(yourage);
 99                 int value=yourage-studentlist.get(near).getage();
100                 System.out.println(""+studentlist.get(near));
101                 break;
102             case "5":
103                 isTrue = false;
104                 System.out.println("退出程序!");
105                 break;
106                 default:
107                 System.out.println("输入有误");
108 
109             }
110         }
111     }
112         public static int agenear(int age) {      
113         int j=0,min=53,value=0,k=0;
114          for (int i = 0; i < studentlist.size(); i++)
115          {
116              value=studentlist.get(i).getage()-age;
117              if(value<0) value=-value; 
118              if (value<min) 
119              {
120                 min=value;
121                 k=i;
122              } 
123           }    
124          return k;         
125       }
126 
127 }

public class Student implements Comparable<Student> {
 2 
 3     private String name;
 4     private String number ;
 5     private String sex ;
 6     private int age;
 7     private String province;
 8    
 9     public String getName() {
10         return name;
11     }
12     public void setName(String name) {
13         this.name = name;
14     }
15     public String getnumber() {
16         return number;
17     }
18     public void setnumber(String number) {
19         this.number = number;
20     }
21     public String getsex() {
22         return sex ;
23     }
24     public void setsex(String sex ) {
25         this.sex =sex ;
26     }
27     public int getage() {
28 
29         return age;
30         }
31         public void setage(int age) {
32             // int a = Integer.parseInt(age);
33         this.age= age;
34         }
35 
36     public String getprovince() {
37         return province;
38     }
39     public void setprovince(String province) {
40         this.province=province ;
41     }
42 
43     public int compareTo(Student o) {
44        return this.name.compareTo(o.getName());
45     }
46 
47     public String toString() {
48         return  name+"\t"+sex+"\t"+age+"\t"+number+"\t"+province+"\n";
49     }    
50 }

package 运算;

import java.util.Scanner;

public class Demo {
	public static void main(String[] args) {
	// 用户的答案要从键盘输入，因此需要一个键盘输入流
@SuppressWarnings("resource")
	Scanner in = new Scanner(System.in);
	// 定义一个变量用来统计得分
int sum = 0;
	// 通过循环生成10道题
for (int i = 0; i < 10; i++) {

// 随机生成两个10以内的随机数作为被除数和除数
int a = (int) Math.round(Math.random() * 10);
	int b = (int) Math.round(Math.random() * 10);
	System.out.println(a + "/" + b + "=");
	// 定义一个整数用来接收用户输入的答案
int c = in.nextInt();
	// 判断用户输入的答案是否正确，正确给10分，错误不给分
if (c == a / b) {
	sum += 10;
	System.out.println("恭喜答案正确");
	}
else {
	System.out.println("抱歉，答案错误");
	}
	}
	//输出用户的成绩
System.out.println("你的得分为"+sum);
	}
}

package 运算;

public class Yuns {
	public int add(int a,int b)
 {
 return a+b;
 }
 public int reduce(int a,int b)
 {
 if((a-b)>0)
 return a-b;
 else return 0;
 }
 public int multiply(int a,int b)
 {
 return a*b;
 }
 public int devision(int a,int b)
 {
 if(b!=0)
 return a/b;
 else return 0;

}

import java.util.Vector;

//示例程序1

class Cat {
    private int catNumber;

    Cat(int i) {
        catNumber = i;
    }

    void print() {
        System.out.println("Cat #" + catNumber);
    }
}
class Dog {
    private int dogNumber;

    Dog(int i) {
        dogNumber = i;
    }

    void print() {
        System.out.println("Dog #" + dogNumber);
    }
}
public class CatsAndDogs {
    public static void main(String[] args) {
        Vector cats = new Vector();//创建一个新的类
        for (int i = 0; i < 7; i++)
            cats.addElement(new Cat(i));
        cats.addElement(new Dog(7));
        for (int i = 0; i < cats.size(); i++)
        if(cats.elementAt(i)instanceof Cat)// instanceof运算符是用来指出对象是否是特定类的一个实例
        {    
            ((Cat) cats.elementAt(i)).print();
        }else {
            ((Dog) cats.elementAt(i)).print();
        }
    }}

//示例程序2
import java.util.*;

public class Stacks {
    static String[] months = { "1", "2", "3", "4" };

    public static void main(String[] args) {
        Stack stk = new Stack();
        for (int i = 0; i < months.length; i++)
            stk.push(months[i]);//放入一个i值
        System.out.println(stk);
        System.out.println("element 2=" + stk.elementAt(2));//element表示一个节点
        while (!stk.empty())
            System.out.println(stk.pop());//出栈操作
    }
}

Stacks

import java.util.*;

class Counter {
    int i = 1;
    public String toString() {
        return Integer.toString(i);
    }
    }
public class Statistics {
    public static void main(String[] args) {
        Hashtable ht = new Hashtable();//生成集合类Hashtable
        for (int i = 0; i < 10000; i++) //生成循环体
        {
            Integer r = new Integer((int) (Math.random() * 20));//随机生成实数定义为整型
            if (ht.containsKey(r))
                ((Counter) ht.get(r)).i++;//用来判断r是否为一个间值
            else
                ht.put(r, new Counter());//创建新的Counter对象
        }
        System.out.println(ht);
    }
}

import java.util.*;

public class ArrayListDemo {
    public static void main(String[] argv) {
        ArrayList al = new ArrayList();
        //用Add来添加对象且可以重载
        // Add lots of elements to the ArrayList...
        al.add(new Integer(11));
        al.add(new Integer(12));
        al.add(new Integer(13));
        al.add(new String("hello"));
        System.out.println(al.size());//输出al的长度
        // First print them out using a for loop.
        System.out.println("Retrieving by index:");
        for (int i = 0; i < al.size(); i++) {
            System.out.println("Element " + i + " = " + al.get(i));
        }
    }
}

ArrayListDemo

mport java.util.*;
public class LinkedListDemo {
    public static void main(String[] argv) {
        LinkedList l = new LinkedList();
        l.add(new Object());
        l.add("Hello");
        l.add("zhangsan");//add方法可以重载
       
        ListIterator li = l.listIterator(0);//迭代器生成li对象
        while (li.hasNext())//hasNext方法用来返回迭代器的对象
            System.out.println(li.next());
        if (l.indexOf("Hello") < 0) //生成循环语句判断最后结果 
            System.err.println("Lookup does not work");
        else
            System.err.println("Lookup works");
   }
}

LinkedListDemo

import java.util.*;
public class SetDemo {
    public static void main(String[] argv) {
        HashSet h = new HashSet(); //也可以 Set h=new HashSet()
        h.add("One");
        h.add("Two");
        h.add("One"); // DUPLICATE
        h.add("Three");
        Iterator it = h.iterator();
        while (it.hasNext()) //hasNext方法
        {
             System.out.println(it.next());
        }
    }
}

 SetDemo

package set;


import java.util.*;

/**
 * This program uses a set to print all unique words in System.in.
 * @version 1.12 2015-06-21
 * @author Cay Horstmann
 */
public class SetTest
{
   public static void main(String[] args)
   {
       
      Set<String> words = new HashSet<>(); // HashSet implements Set
      long totalTime = 0;
      
      try (Scanner in = new Scanner(System.in))
      {
         while (in.hasNext())//迭代器的用法，判断当前元素是否存在
         {
            String word = in.next();//指向下一个元素
            long callTime = System.currentTimeMillis();
            words.add(word);//
            callTime = System.currentTimeMillis() - callTime;
            totalTime += callTime;
         }
      }

      Iterator<String> iter = words.iterator();//迭代器的简单实现
      for (int i = 1; i <= 20 && iter.hasNext(); i++)
         System.out.println(iter.next());
      System.out.println(". . .");
      System.out.println(words.size() + " distinct words. " + totalTime + " milliseconds.");
   }
}

package treeSet;

import java.util.*;

/**
 * This program sorts a set of item by comparing their descriptions.
 * @version 1.12 2015-06-21
 * @author Cay Horstmann
 */
public class TreeSetTest
{
   public static void main(String[] args)
   {
      SortedSet<Item> parts = new TreeSet<>();
      parts.add(new Item("Toaster", 1234));//add方法
      parts.add(new Item("Widget", 4562));
      parts.add(new Item("Modem", 9912));
      System.out.println(parts);

      NavigableSet<Item> sortByDescription = new TreeSet<>(
            Comparator.comparing(Item::getDescription));

      sortByDescription.addAll(parts);
      System.out.println(sortByDescription);
   }
}

TreeSetTest

package treeSet;

import java.util.*;

/**
 * An item with a description and a part number.
 */
public class Item implements Comparable<Item>//Item类实现Comparable接口
{
   private String description;
   private int partNumber;

   /**
    * Constructs an item.
    * 
    * @param aDescription
    *           the item''s description
    * @param aPartNumber
    *           the item''s part number
    */
   public Item(String aDescription, int aPartNumber)
   {
      description = aDescription;//字符串
      partNumber = aPartNumber;
   }

   /**
    * Gets the description of this item.
    * 
    * @return the description
    */
   public String getDescription()
   {
      return description;
   }

   public String toString()
   {
      return "[description=" + description + ", partNumber=" + partNumber + "]";
   }//返回该对象的字符串表示

   public boolean equals(Object otherObject)
   {
      if (this == otherObject) return true;
      if (otherObject == null) return false;
      if (getClass() != otherObject.getClass()) return false;
      Item other = (Item) otherObject;
      return Objects.equals(description, other.description) && partNumber == other.partNumber;
   }

   public int hashCode()
   {
      return Objects.hash(description, partNumber);
   }

   public int compareTo(Item other)
   {
      int diff = Integer.compare(partNumber, other.partNumber);
      return diff != 0 ? diff : description.compareTo(other.description);
   }
}

Item

import java.util.*;
public class HashMapDemo {
   public static void main(String[] argv) {
      HashMap h = new HashMap();
      // The hash maps from company name to address.
      h.put("Adobe", "Mountain View, CA");//定义对象
      h.put("IBM", "White Plains, NY");
      h.put("Sun", "Mountain View, CA");
      String queryString = "Adobe";
      String resultString = (String)h.get(queryString);
      System.out.println("They are located in: " +  resultString);
  }
}

package map;

import java.util.*;

/**
 * This program demonstrates the use of a map with key type String and value type Employee.
 * @version 1.12 2015-06-21
 * @author Cay Horstmann
 */
public class MapTest
{
   public static void main(String[] args)
   {
      Map<String, Employee> staff = new HashMap<>();//HashMap implements Map
      staff.put("144-25-5464", new Employee("Amy Lee"));
      staff.put("567-24-2546", new Employee("Harry Hacker"));
      staff.put("157-62-7935", new Employee("Gary Cooper"));
      staff.put("456-62-5527", new Employee("Francesca Cruz"));

      // print all entries

      System.out.println(staff);

      // remove an entry

      staff.remove("567-24-2546");

      // replace an entry

      staff.put("456-62-5527", new Employee("Francesca Miller"));

      // look up a value

      System.out.println(staff.get("157-62-7935"));

      // iterate through all entries

      staff.forEach((k, v) -> 
         System.out.println("key=" + k + ", value=" + v));
   }
}

import java.io.BufferedReader;
import java.io.File;
import java.io.FileInputStream;
import java.io.FileNotFoundException;
import java.io.IOException;
import java.io.InputStreamReader;
import java.util.ArrayList;
import java.util.Arrays;
import java.util.Scanner;
import java.util.Collections;//对集合进行排序、查找、修改等；

public class Test {
    private static ArrayList<Citizen> citizenlist;

    public static void main(String[] args) {
        citizenlist = new ArrayList<>();
        Scanner scanner = new Scanner(System.in);
        File file = new File("E:/java/身份证号.txt");
        //异常捕获
        try {
            FileInputStream fis = new FileInputStream(file);
            BufferedReader in = new BufferedReader(new InputStreamReader(fis));
            String temp = null;
            while ((temp = in.readLine()) != null) {

                Scanner linescanner = new Scanner(temp);

                linescanner.useDelimiter(" ");
                String name = linescanner.next();
                String id = linescanner.next();
                String sex = linescanner.next();
                String age = linescanner.next();
                String birthplace = linescanner.nextLine();
                Citizen citizen = new Citizen();
                citizen.setName(name);
                citizen.setId(id);
                citizen.setSex(sex);
                // 将字符串转换成10进制数
                int ag = Integer.parseInt(age);
                citizen.setage(ag);
                citizen.setBirthplace(birthplace);
                citizenlist.add(citizen);

            }
        } catch (FileNotFoundException e) {
            System.out.println("信息文件找不到");
            e.printStackTrace();
        } catch (IOException e) {
            System.out.println("信息文件读取错误");
            e.printStackTrace();
        }
        boolean isTrue = true;
        while (isTrue) {

            System.out.println("1.按姓名字典序输出人员信息");
            System.out.println("2.查询最大年龄的人员信息、查询最小年龄人员信息");
            System.out.println("3.查询人员中是否查询人员中是否有你的同乡");
            System.out.println("4.输入你的年龄，查询文件中年龄与你最近人的姓名、身份证号、年龄、性别和出生地");
            System.out.println("5.退出");
            int nextInt = scanner.nextInt();
            switch (nextInt) {
            case 1:
                Collections.sort(citizenlist);
                System.out.println(citizenlist.toString());
                break;
            case 2:
                int max = 0, min = 100;
                int m, k1 = 0, k2 = 0;
                for (int i = 1; i < citizenlist.size(); i++) {
                    m = citizenlist.get(i).getage();
                    if (m > max) {
                        max = m;
                        k1 = i;
                    }
                    if (m < min) {
                        min = m;
                        k2 = i;
                    }
                }
                System.out.println("年龄最大：" + citizenlist.get(k1));
                System.out.println("年龄最小：" + citizenlist.get(k2));
                break;
            case 3:
                System.out.println("出生地：");
                String find = scanner.next();
                String place = find.substring(0, 3);
                for (int i = 0; i < citizenlist.size(); i++) {
                    if (citizenlist.get(i).getBirthplace().substring(1, 4).equals(place))
                        System.out.println("出生地" + citizenlist.get(i));
                }
                break;
            case 4:
                System.out.println("年龄：");
                int yourage = scanner.nextInt();
                int near = peer(yourage);
                int j = yourage - citizenlist.get(near).getage();
                System.out.println("" + citizenlist.get(near));
                break;
            case 5:
                isTrue = false;
                System.out.println("程序已退出!");
                break;
            default:
                System.out.println("输入有误");
            }
        }
    }

    public static int peer(int age) {
        int flag = 0;
        int min = 53, j = 0;
        for (int i = 0; i < citizenlist.size(); i++) {
            j = citizenlist.get(i).getage() - age;
            if (j < 0)
                j = -j;
            if (j < min) {
                min = j;
                flag = i;
            }
        }
        return flag;
    }
}

test

public class Citizen implements Comparable<Citizen> {

    private String name;
    private String id;
    private String sex;
    private int age;
    private String birthplace;

    public String getName() {
        return name;
    }

    public void setName(String name) {
        this.name = name;
    }

    public String getId() {
        return id;
    }

    public void setId(String id) {
        this.id = id;
    }

    public String getSex() {
        return sex;
    }

    public void setSex(String sex) {
        this.sex = sex;
    }

    public int getage() {
        return age;
    }

    public void setage(int age) {
        this.age = age;
    }

    public String getBirthplace() {
        return birthplace;
    }

    public void setBirthplace(String birthplace) {
        this.birthplace = birthplace;
    }

    public int compareTo(Citizen other) {
        return this.name.compareTo(other.getName());
    }

    public String toString() {
        return name + "\t" + sex + "\t" + age + "\t" + id + "\t" + birthplace + "\n";
    }
}

citizen

import java.io.FileNotFoundException;
import java.io.IOException;
import java.io.PrintWriter;
import java.util.Scanner;

public class calculator {

    public static void main(String[] args) {
        Scanner in = new Scanner(System.in);
        Count count=new Count();
        PrintWriter out = null;
        try {
            out = new PrintWriter("test.txt");
            int sum = 0;
            for (int i = 1; i <=10; i++) {
                int a = (int) Math.round(Math.random() * 100);
                int b = (int) Math.round(Math.random() * 100);
                int menu = (int) Math.round(Math.random() * 3);
                switch (menu) {
                case 0:
                    System.out.println(i+":"+a + "+" + b + "=");
                    int c1 = in.nextInt();
                    out.println(a + "+" + b + "=" + c1);
                    if (c1 == (a + b)) {
                        sum += 10;
                        System.out.println("恭喜答案正确");
                    } else {
                        System.out.println("抱歉，答案错误");
                    }
                    break;
                case 1:
                    while (a < b) {
                        b = (int) Math.round(Math.random() * 100);
                    }
                    System.out.println(i+":"+a + "-" + b + "=");
                    int c2 = in.nextInt();
                    out.println(a + "-" + b + "=" + c2);
                    if (c2 == (a - b)) {
                        sum += 10;
                        System.out.println("恭喜答案正确");
                    } else {
                        System.out.println("抱歉，答案错误");
                    }

                    break;
                case 2:
                    System.out.println(i+":"+a + "*" + b + "=");
                    int c3 = in.nextInt();
                    out.println(a + "*" + b + "=" + c3);
                    if (c3 == a * b) {
                        sum += 10;
                        System.out.println("恭喜答案正确");
                    } else {
                        System.out.println("抱歉，答案错误");
                    }

                    break;
                case 3:
                     while(b == 0){
                            b = (int) Math.round(Math.random() * 100);
                        }
                        while(a % b != 0){
                            a = (int) Math.round(Math.random() * 100);
                            
                        }
                    System.out.println(i+":"+a + "/" + b + "=");
                    int c4 = in.nextInt();
                    if (c4 == a / b) {
                        sum += 10;
                        System.out.println("恭喜答案正确");
                    } else {
                        System.out.println("抱歉，答案错误");
                    }

                    break;
                }
            }
            System.out.println("你的得分为" + sum);
            out.println("你的得分为" + sum);
            out.close();
        } catch (FileNotFoundException e) {
            e.printStackTrace();
        }
    }

}

calculate

public class Count<T> {
    private T a;
    private T b;
    public Count() {
        a=null;
        b=null;
    }
    public Count(T a,T b) {
        this.a=a;
        this.b=b;
    }
    public int count1(int a,int b) {
        return a+b;
    }
    public int count2(int a,int b) {
        return a-b;
    }
    public int count3(int a,int b) {
        return a*b;
    }
    public int count4(int a,int b) {
        return a/b;
    }
}

count

import java.io.BufferedReader;
import java.io.File;
import java.io.FileInputStream;
import java.io.FileNotFoundException;
import java.io.IOException;
import java.io.InputStreamReader;
import java.util.ArrayList;
import java.util.Arrays;
import java.util.Collections;
import java.util.List;
import java.util.Scanner;

public class Xinxi {
    private static ArrayList<Student> studentlist;

    
    public static  void main(String[] args) {
        studentlist = new ArrayList<>();
        Scanner scanner = new Scanner(System.in);
        File file = new File("D:\\身份证号\\身份证号.txt");
        try {
            FileInputStream fis = new FileInputStream(file);
            BufferedReader in = new BufferedReader(new InputStreamReader(fis));
            String temp = null;
            while ((temp = in.readLine()) != null) {

                Scanner linescanner = new Scanner(temp);

                linescanner.useDelimiter(" ");
                String name = linescanner.next();
                String number = linescanner.next();
                String sex = linescanner.next();
                String age = linescanner.next();
                String province = linescanner.nextLine();
                Student student = new Student();
                student.setName(name);
                student.setnumber(number);
                student.setsex(sex);
                int a = Integer.parseInt(age);
                student.setage(a);
                student.setprovince(province);
                studentlist.add(student);

            }
        } catch (FileNotFoundException e) {//添加的异常处理语句try{   }catch{   }语句
            System.out.println("所找信息文件找不到");
            e.printStackTrace();
        } catch (IOException e) {
            System.out.println("所找信息文件读取错误");//采取积极方法捕获异常，并将异常返回自己所设定的打印文字
            e.printStackTrace();
        }
        boolean isTrue = true;
        while (isTrue) {
            System.out.println("选择你的操作，输入正确格式的选项");
            System.out.println("1按姓名字典序输出人员信息");
            System.out.println("2.查询最大和最小年龄的人员信息");

            System.out.println("3.寻找年龄相近的人的信息");
            System.out.println("4.寻找老乡");

            System.out.println("5.退出");
            String n = scanner.next();
            switch (n) {
            case "1":
                Collections.sort(studentlist);
                System.out.println(studentlist.toString());
                break;
            case "2":
                int max = 0, min = 100;
                int j, k1 = 0, k2 = 0;
                for (int i = 1; i < studentlist.size(); i++) {
                    j = studentlist.get(i).getage();
                    if (j > max) {
                        max = j;
                        k1 = i;
                    }
                    if (j < min) {
                        min = j;
                        k2 = i;
                    }

                }
                System.out.println("年龄最大：" + studentlist.get(k1));

                System.out.println("年龄最小：" + studentlist.get(k2));
                break;
            case "3":
                System.out.println("家乡在哪里？");
                String find = scanner.next();
                String place = find.substring(0, 3);
                for (int i = 0; i < studentlist.size(); i++) {
                    if (studentlist.get(i).getprovince().substring(1, 4).equals(place))
                        System.out.println("同乡" + studentlist.get(i));
                }
                break;

            case "4":
                System.out.println("年龄：");
                int yourage = scanner.nextInt();
                int near = agenear(yourage);
                int value = yourage - studentlist.get(near).getage();
                System.out.println("" + studentlist.get(near));
                break;
            case "5":
                isTrue = false;
                System.out.println("退出程序!");
                break;
            default:
                System.out.println("输入有误");

            }
        }
    }

    public static int agenear(int age) {
        int j = 0, min = 53, value = 0, flag = 0;
        for (int i = 0; i < studentlist.size(); i++) {
            value = studentlist.get(i).getage() - age;
            if (value < 0)
                value = -value;
            if (value < min) {
                min = value;
                flag = i;
            }
        }
        return flag;
    }

}

xinxi

xinxi

public  class Student implements Comparable<Student> {

    private String name;
    private String number;
    private String sex;
    private String province;
    private int age;

    public void setName(String name) {
        // TODO 自动生成的方法存根
        this.name = name;

    }

    public String getName() {
        // TODO 自动生成的方法存根
        return name;
    }

    public void setnumber(String number) {
        // TODO 自动生成的方法存根
        this.number = number;
    }

    public String getNumber() {
        // TODO 自动生成的方法存根
        return number;
    }

    public void setsex(String sex) {
        // TODO 自动生成的方法存根
        this.sex = sex;
    }

    public String getsex() {
        // TODO 自动生成的方法存根
        return sex;
    }

    public void setprovince(String province) {
        // TODO 自动生成的方法存根
        this.province = province;
    }

    public String getprovince() {
        // TODO 自动生成的方法存根
        return province;
    }

    public void setage(int a) {
        // TODO 自动生成的方法存根
        this.age = age;
    }

    public int getage() {
        // TODO 自动生成的方法存根
        return age;
    }

    public int compareTo(Student o) {
        return this.name.compareTo(o.getName());
    }

    public String toString() {
        return name + "\t" + sex + "\t" + age + "\t" + number + "\t" + province + "\n";
    }
}

student类

student

import java.io.FileNotFoundException;
import java.io.IOException;
import java.io.PrintWriter;
import java.util.Scanner;

public class calculator {

    public static void main(String[] args) {
        Scanner in = new Scanner(System.in);
        Count count=new Count();
        PrintWriter out = null;
        try {
            out = new PrintWriter("test.txt");
            int sum = 0;
            for (int i = 1; i <=10; i++) {
                int a = (int) Math.round(Math.random() * 100);
                int b = (int) Math.round(Math.random() * 100);
                int menu = (int) Math.round(Math.random() * 3);
                switch (menu) {
                case 0:
                    System.out.println(i+":"+a + "+" + b + "=");
                    int c1 = in.nextInt();
                    out.println(a + "+" + b + "=" + c1);
                    if (c1 == (a + b)) {
                        sum += 10;
                        System.out.println("恭喜答案正确");
                    } else {
                        System.out.println("抱歉，答案错误");
                    }
                    break;
                case 1:
                    while (a < b) {
                        b = (int) Math.round(Math.random() * 100);
                    }
                    System.out.println(i+":"+a + "-" + b + "=");
                    int c2 = in.nextInt();
                    out.println(a + "-" + b + "=" + c2);
                    if (c2 == (a - b)) {
                        sum += 10;
                        System.out.println("恭喜答案正确");
                    } else {
                        System.out.println("抱歉，答案错误");
                    }

                    break;
                case 2:
                    System.out.println(i+":"+a + "*" + b + "=");
                    int c3 = in.nextInt();
                    out.println(a + "*" + b + "=" + c3);
                    if (c3 == a * b) {
                        sum += 10;
                        System.out.println("恭喜答案正确");
                    } else {
                        System.out.println("抱歉，答案错误");
                    }

                    break;
                case 3:
                     while(b == 0){
                            b = (int) Math.round(Math.random() * 100);
                        }
                        while(a % b != 0){
                            a = (int) Math.round(Math.random() * 100);
                            
                        }
                    System.out.println(i+":"+a + "/" + b + "=");
                    int c4 = in.nextInt();
                    if (c4 == a / b) {
                        sum += 10;
                        System.out.println("恭喜答案正确");
                    } else {
                        System.out.println("抱歉，答案错误");
                    }

                    break;
                }
            }
            System.out.println("你的得分为" + sum);
            out.println("你的得分为" + sum);
            out.close();
        } catch (FileNotFoundException e) {
            e.printStackTrace();
        }
    }

}

calculate

public class Count<T> {
    private T a;
    private T b;
    public Count() {
        a=null;
        b=null;
    }
    public Count(T a,T b) {
        this.a=a;
        this.b=b;
    }
    public int count1(int a,int b) {
        return a+b;
    }
    public int count2(int a,int b) {
        return a-b;
    }
    public int count3(int a,int b) {
        return a*b;
    }
    public int count4(int a,int b) {
        return a/b;
    }
}

count