让我说我有一个单词列表,我想创建一个方法,将新列表的大小作为参数,并返回新列表.我如何从原始sourceList中获取随机的单词？

public List<String> createList(int listSize) {
   Random rand = new Random();
   List<String> wordList = sourceWords.
      stream().
      limit(listSize).
      collect(Collectors.toList()); 

   return wordList;
}

那么如何和在哪里可以使用我的随机？

我找到了一个正确的解决方案.
随机提供了一些返回流的方法.例如,创建一个随机整数流的int(size).

public List<String> createList(int listSize)
{
   Random rand = new Random();
   List<String> wordList = rand.
      ints(listSize,sourceWords.size()).
      mapToObj(i -> sourceWords.get(i)).
      collect(Collectors.toList());

   return wordList;
}

我有一个应该呈现随机颜色的功能,但不重复颜色.

意思是如果随机选择蓝色,则无法再次选择.当然,这意味着需要一个默认值.我在考虑使用switch语句.

这是我目前的代码：

const colors = {
      grey: '#BDC8D1',blue: '#0500FF',pink: '#FF00C7',orange: '#FF7A00'
    }

    const randomColor = () => {
      let keys = Object.keys(colors)
      return colors[keys[keys.length * Math.random() << 0]]
    }

您可以“使用”一系列有效值来返回.通过消费我的意思是,从数组中删除它们.

例如：

// List of all valid values (those that can be returned)
const colors = [ 'red','green','blue' ];

// The default color (when all others have been "consumed")
const defaultColor = 'black'; 

// The function that returns a random color
const getRandomColor = () => {
    // At least we return a color
    let color = defaultColor;

    // If all colors were prevIoUsly consumed,we won't need
    // to pick one randomly
    if (colors.length > 0) {
        // We select randomly an index from the colors array
        const index = Math.floor(colors.length * Math.random());

        // We store the color to return
        color = colors[index];

        // We remove it from the array
        colors.splice(index,1);
    }
    
    return color;
};

console.log(getRandomColor());
console.log(getRandomColor());
console.log(getRandomColor());
console.log(getRandomColor());
console.log(getRandomColor());
console.log(getRandomColor());

此解决方案的明显问题是您无法多次重复使用您的函数.
更好的解决方案是创建迭代器.每次应用程序的某些部分需要生成随机的一系列颜色时,您将创建一个新的迭代器,并使用其下一个方法来获取新值.
检查以下内容：

// The default color (when all others have been "consumed")
const defaultColor = 'black'; 

const RandomColorIterator = () => {
    // List of all valid values (those that can be returned)
    const colors = [ 'red','blue' ];
    
    return {
        next: () => {
            // At least we return a color
            let color = defaultColor;

            // If all colors were prevIoUsly consumed,we won't need
            // to pick one randomly
            if (colors.length > 0) {
                // We select randomly an index from the colors array
                const index = Math.floor(colors.length * Math.random());

                // We store the color to return
                color = colors[index];

                // We remove it from the array
                colors.splice(index,1);
            }

            return color;
        },};
};

const iterator1 = RandomColorIterator();
console.log('1:',iterator1.next());
console.log('1:',iterator1.next());

const iterator2 = RandomColorIterator();
console.log('2:',iterator2.next());
console.log('2:',iterator2.next());

我一直在使用箭头功能从父范围中获利.这允许基于每个呼叫访问颜色.