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关于在JSP中使用request.getParameter会导致NullPointerException的问题就给大家分享到这里，感谢你花时间阅读本站内容，更多关于android – ContextWrapper.getResources()中的NullPointerException、android – 在onDestory()中停止/释放Mediaplayer会导致NullPointerException、android – 照片捕获意图仅在Samsung手机上导致NullPointerException、Android,NetworkInfo.getTypeName(),NullpointerException等相关知识的信息别忘了在本站进行查找喔。
本文目录一览：- 在JSP中使用request.getParameter会导致NullPointerException
- android – ContextWrapper.getResources()中的NullPointerException
- android – 在onDestory()中停止/释放Mediaplayer会导致NullPointerException
- android – 照片捕获意图仅在Samsung手机上导致NullPointerException
- Android,NetworkInfo.getTypeName(),NullpointerException
在JSP中使用request.getParameter会导致NullPointerException
尝试获取查询字符串参数并在JSP页面中采取适当的措施。
这是一个片段：
<%@ page import="com.companyx.portal.model.LDAPAttributes" %>
<%@ page import="com.companyx.portal.service.LDAPAttributesLocalServiceUtil" %>
<%@ page import="com.liferay.portal.model.User" %>
<%@ page import="com.liferay.portal.util.PortalUtil" %>
<%@ page import="javax.servlet.http.HttpServletRequest" %>
<%
User user = PortalUtil.getUser(request);
String screenName = user.getScreenName();
LDAPAttributes attr = LDAPAttributesLocalServiceUtil.getLDAPAttributes(screenName);
String store = attr.getLegacyStoreNo();
String org = request.getParameter("org");
%>
...more code here...
<html>
...html code here...
<form name="LoginForm" action="check_login.php">
<input type="hidden" name="LOGIN_NAME" size="20" value="<%= store %>" />
<input type="hidden" name="LOGIN_PASSWORD" size="20" value="<%= store %>" />
<input type="hidden" name="ORGANIZATION" value="<%= org %>" />
</form>
当以下行不存在时：
String org = request.getParameter("org");
...
<input type="hidden" name="ORGANIZATION" value="<%= org %>" />
该脚本可以正常工作，但是我需要从查询字符串中捕获一个’org’参数，将其写入生成的表单中并提交。但是，当这些行存在时，我会收到500错误。
有什么想法吗？
android – ContextWrapper.getResources()中的NullPointerException
我真的不知道我正在构建的
Android应用程序发生了什么.在它开发的某个时刻,我开始在模拟器中启动它,并显示消息“Foo stopped”.这是错误日志,如果有人可以帮助我：
07-05 21:13:30.063 7647-7647/root.fazerumsom E/AndroidRuntime﹕ FATAL EXCEPTION: main
Process: root.fazerumsom,PID: 7647
java.lang.RuntimeException: Unable to instantiate activity ComponentInfo{root.fazerumsom/root.fazerumsom.MainActivity}: java.lang.NullPointerException
at android.app.ActivityThread.performlaunchActivity(ActivityThread.java:2110)
at android.app.ActivityThread.handleLaunchActivity(ActivityThread.java:2233)
at android.app.ActivityThread.access$800(ActivityThread.java:135)
at android.app.ActivityThread$H.handleMessage(ActivityThread.java:1196)
at android.os.Handler.dispatchMessage(Handler.java:102)
at android.os.Looper.loop(Looper.java:136)
at android.app.ActivityThread.main(ActivityThread.java:5001)
at java.lang.reflect.Method.invokeNative(Native Method)
at java.lang.reflect.Method.invoke(Method.java:515)
at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:785)
at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:601)
at dalvik.system.NativeStart.main(Native Method)
Caused by: java.lang.NullPointerException
at android.content.Contextwrapper.getResources(Contextwrapper.java:89)
at android.view.ContextThemeWrapper.getResources(ContextThemeWrapper.java:78)
at root.fazerumsom.MainActivity.<init>(MainActivity.java:31)
at java.lang.class.newInstanceImpl(Native Method)
at java.lang.class.newInstance(Class.java:1208)
at android.app.Instrumentation.newActivity(Instrumentation.java:1061)
at android.app.ActivityThread.performlaunchActivity(ActivityThread.java:2101)
at android.app.ActivityThread.handleLaunchActivity(ActivityThread.java:2233)
at android.app.ActivityThread.access$800(ActivityThread.java:135)
at android.app.ActivityThread$H.handleMessage(ActivityThread.java:1196)
at android.os.Handler.dispatchMessage(Handler.java:102)
at android.os.Looper.loop(Looper.java:136)
at android.app.ActivityThread.main(ActivityThread.java:5001)
at java.lang.reflect.Method.invokeNative(Native Method)
at java.lang.reflect.Method.invoke(Method.java:515)
at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:785)
at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:601)
at dalvik.system.NativeStart.main(Native Method)
解决方法
您正在从字段初始值设定项中调用getResources().就像是
private String mStr = getResources().getString(...);
(或使用drawables或其他类型的资源).
这是无效的,因为尚未设置Context.在onCreate()方法中移动此赋值.
android – 在onDestory()中停止/释放Mediaplayer会导致NullPointerException
我试图在onDestroy()中停止并释放MediaPlayer对象,但应用程序一直在崩溃.这是代码：
void StartSound(final String ReaderPath) {
mediaplayer = MediaPlayer.create(test2.this,Uri.parse(ReaderPath));
try {
mediaplayer.start();
mediaplayer.setonCompletionListener(new OnCompletionListener() {
@Override
public void onCompletion(MediaPlayer mp) {
current++;
try {
mp.reset();
mp.setDataSource(ReaderPath);
mp.prepare();
} catch (Exception e) {
e.printstacktrace();
}
mp.start();
}
});
} catch (Exception e) {
}
}
@Override
protected void onPause() {
if (mediaplayer != null && mediaplayer.isPlaying())
mediaplayer.pause();
super.onPause();
}
@Override
protected void onStop() {
if (mediaplayer != null && mediaplayer.isPlaying()) {
mediaplayer.release();
mediaplayer.stop();
}
super.onDestroy();
}
logcat的：
08-21 22:52:26.512: E/AndroidRuntime(16410): java.lang.RuntimeException: Unable to destroy activity {com.example.test/com.example.test.test2}: java.lang.NullPointerException
08-21 22:52:26.512: E/AndroidRuntime(16410): at android.app.ActivityThread.performDestroyActivity(ActivityThread.java:3235)
08-21 22:52:26.512: E/AndroidRuntime(16410): at android.app.ActivityThread.handleDestroyActivity(ActivityThread.java:3253)
08-21 22:52:26.512: E/AndroidRuntime(16410): at android.app.ActivityThread.access$1200(ActivityThread.java:132)
08-21 22:52:26.512: E/AndroidRuntime(16410): at android.app.ActivityThread$H.handleMessage(ActivityThread.java:1190)
08-21 22:52:26.512: E/AndroidRuntime(16410): at android.os.Handler.dispatchMessage(Handler.java:99)
08-21 22:52:26.512: E/AndroidRuntime(16410): at android.os.Looper.loop(Looper.java:137)
08-21 22:52:26.512: E/AndroidRuntime(16410): at android.app.ActivityThread.main(ActivityThread.java:4575)
08-21 22:52:26.512: E/AndroidRuntime(16410): at java.lang.reflect.Method.invokeNative(Native Method)
08-21 22:52:26.512: E/AndroidRuntime(16410): at java.lang.reflect.Method.invoke(Method.java:511)
08-21 22:52:26.512: E/AndroidRuntime(16410): at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:786)
08-21 22:52:26.512: E/AndroidRuntime(16410): at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:553)
08-21 22:52:26.512: E/AndroidRuntime(16410): at dalvik.system.NativeStart.main(Native Method)
08-21 22:52:26.512: E/AndroidRuntime(16410): Caused by: java.lang.NullPointerException
08-21 22:52:26.512: E/AndroidRuntime(16410): at android.support.v4.app.FragmentManagerImpl.execPendingActions(FragmentManager.java:1406)
08-21 22:52:26.512: E/AndroidRuntime(16410): at android.support.v4.app.FragmentManagerImpl.dispatchDestroy(FragmentManager.java:1876)
08-21 22:52:26.512: E/AndroidRuntime(16410): at android.support.v4.app.FragmentActivity.onDestroy(FragmentActivity.java:316)
08-21 22:52:26.512: E/AndroidRuntime(16410): at android.app.Activity.performDestroy(Activity.java:4629)
08-21 22:52:26.512: E/AndroidRuntime(16410): at android.app.Instrumentation.callActivityOnDestroy(Instrumentation.java:1079)
08-21 22:52:26.512: E/AndroidRuntime(16410): at android.app.ActivityThread.performDestroyActivity(ActivityThread.java:3222)
08-21 22:52:26.512: E/AndroidRuntime(16410): ... 11 more
为什么是这样？
解决方法
你为什么要从onStop()方法调用super.onDestroy()？你应该调用super.onStop().或者是输入错误？
答案可能是您在调用release()后调用MediaPlayer上的stop().一旦调用release(),MediaPlayer就会失效并且不再可用.
android – 照片捕获意图仅在Samsung手机上导致NullPointerException
照片捕获意图仅在Samsung手机上导致NullPointerException.
下面的实现.
final Button capture = (Button)findViewById(R.id.capture_button);
capture.setonClickListener(new OnClickListener() {
@Override
public void onClick(View v) {
// Todo Auto-generated method stub
Intent cameraIntent = new Intent(MediaStore.ACTION_IMAGE_CAPTURE);
startActivityForResult(cameraIntent,CAMERA_PIC_REQUEST);
}
});
protected void onActivityResult(int requestCode,int resultCode,Intent data) {
if (requestCode == CAMERA_PIC_REQUEST) {
Bitmap thumbnail = (Bitmap)data.getExtras().get("data");
ImageView image = (ImageView)findViewById(R.id.photoResultView);
image.setimageBitmap(thumbnail);
}
}
解决方法
我发现一个修复(不是我的工作),使其适用于三星设备.有解释的博客可以找到
here.
但是,在非三星手机上使用此修复会返回错误的图像,因此我将使用
if(imageURI != null) {
// do it the normal way
else {
// do it the "Samsung" way
}
Android,NetworkInfo.getTypeName(),NullpointerException
我有一个活动显示一些列表条目.当我点击列表项目时,我的应用程序通过NetworkInfo.getTypeName()检查可用的连接类型(“WIF”或“MOBILE”).一旦我调用这个方法,我得到一个NullpointerException.为什么？
我在模拟器上测试了这个,因为我的手机目前不可用(坏了…).我假设这是问题？这是我唯一的解释,如果不是这样,我不知道为什么这将是null.
以下是一些代码段：
public class VideoList extends ListActivity{
...
public void onCreate(Bundle bundle){
final ConnectivityManager cm = (ConnectivityManager) getSystemService(Context.CONNECTIVITY_SERVICE);
...
listview.setonItemClickListener(new OnItemClickListener(){
public void onItemClick(AdapterView<?> parent,View view,int position,long id) {
...
NetworkInfo ni = cm.getActiveNetworkInfo();
String connex = ni.getTypeName(); //Nullpointer exception here
if(connex.equals("WIFI")doSomething();
}
});
}
}
解决方法
如果没有活动网络,则调用getActiveNetworkInfo()可以返回null,并且需要检查.这是
here的源代码.
/**
* Return NetworkInfo for the active (i.e.,connected) network interface.
* It is assumed that at most one network is active at a time. If more
* than one is active,it is indeterminate which will be returned.
* @return the info for the active network,or {@code null} if none is active
*/
public NetworkInfo getActiveNetworkInfo() {
enforceAccesspermission();
for (NetworkStateTracker t : mNetTrackers) {
NetworkInfo info = t.getNetworkInfo();
if (info.isConnected()) {
return info;
}
}
return null;
}
特别注意javadoc：“返回活动网络的信息,如果没有活动,则返回null”.
今天关于在JSP中使用request.getParameter会导致NullPointerException的分享就到这里，希望大家有所收获，若想了解更多关于android – ContextWrapper.getResources()中的NullPointerException、android – 在onDestory()中停止/释放Mediaplayer会导致NullPointerException、android – 照片捕获意图仅在Samsung手机上导致NullPointerException、Android,NetworkInfo.getTypeName(),NullpointerException等相关知识，可以在本站进行查询。
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