Wie verwende ich RelativeLayout als Header zur Listenansicht

Question

Ich habe eine einfache App, die Benutzer Top-Post-Nachrichten, die andere kommentieren können. Ich habe zwei Aktivitäten die mainActivity und die commentActivity.On MainActivity, wenn ein Benutzer auf einen Beitrag klickt die Listenansicht

Intent intent = new Intent(MainActivity.this, CommentActivity.class); 
intent.putExtra("Appid", post.getObjectId()); 
intent.putExtra("Username", post.getUser().getUsername()); 
intent.putExtra("Text", post.getText()); 
intent.putExtra("vote",Integer.toString(post.getVote())); 
intent.putExtra("Timestamp",Long.toString(post.getTimestamp())); 
startActivity(intent); 

auf der Kommentar-Aktivität abrufen I

String username = intent.getStringExtra("Username"); 
String text  = intent.getStringExtra("Text"); 
post_id   = intent.getStringExtra("Appid"); 
String sum  = intent.getStringExtra("vote"); 
String time  = intent.getStringExtra("Timestamp"); 

und zeigt sie auf einem relativen Layout, das über einer Listenansicht ist. Ich möchte, dass das relative Layout zusammen mit der Listenansicht als 1 angezeigt wird. Was ich getan habe, ist ein separates XML für das relative Layout, das header.xml heißt, das von comment_activity.xml getrennt ist. i am commentActivity versucht, die header.xml aufzublasen und als Header zur Listen

View view= getLayoutInflater().inflate(R.layout.header,null);  
TextView vote_count = (TextView) view.findViewById(R.id.txtVote_Count); 
TextView txtusername =(TextView) view.findViewById(R.id.txtUsername_view_Respond); 
TextView Statusmsg =(TextView) view.findViewById(R.id.txtContent_view_Respond); 


txtusername.setText(username); 
Statusmsg.setText(text); 
timestamp.setText(timeAgo); 

ListView listView = (ListView) 
findViewById(R.id.comment_list_view); 
listView.addHeaderView(view); 
listView.setAdapter(Adapter); 

`

ich einen java.lang.NullPointerException bekommen zu verwenden. Hier ist mein Stack-Trace `

04-20 20:13:29.737 20254-20254/com.example.machimanapc.howzit W/System.err? at android.os.Looper.loop(Looper.java:193) 
04-20 20:13:29.737 20254-20254/com.example.machimanapc.howzit W/System.err? at android.app.ActivityThread.main(ActivityThread.java:5299) 
04-20 20:13:29.737 20254-20254/com.example.machimanapc.howzit W/System.err? at java.lang.reflect.Method.invokeNative(Native Method) 
04-20 20:13:29.737 20254-20254/com.example.machimanapc.howzit W/System.err? at java.lang.reflect.Method.invoke(Method.java:515) 
04-20 20:13:29.739 20254-20254/com.example.machimanapc.howzit W/System.err? at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:825) 
04-20 20:13:29.740 20254-20254/com.example.machimanapc.howzit W/System.err? at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:641) 
04-20 20:13:29.740 20254-20254/com.example.machimanapc.howzit W/System.err? at dalvik.system.NativeStart.main(Native Method) 
04-20 20:13:29.740 20254-20254/com.example.machimanapc.howzit W/System.err? Caused by: java.lang.NullPointerException 
04-20 20:13:29.746 20254-20254/com.example.machimanapc.howzit W/System.err? at com.example.machimanapc.howzit.CommentActivity.onCreate(CommentActivity.java:196) 
04-20 20:13:29.746 20254-20254/com.example.machimanapc.howzit W/System.err? at android.app.Activity.performCreate(Activity.java:5264) 
04-20 20:13:29.746 20254-20254/com.example.machimanapc.howzit W/System.err? at android.app.Instrumentation.callActivityOnCreate(Instrumentation.java:1088) 
04-20 20:13:29.746 20254-20254/com.example.machimanapc.howzit W/System.err? at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:2302) 
04-20 20:13:29.746 20254-20254/com.example.machimanapc.howzit W/System.err? ... 11 more 
04-20 20:13:29.746 20254-20254/com.example.machimanapc.howzit W/dalvikvm? threadid=1: calling UncaughtExceptionHandler 
04-20 20:13:29.751 20254-20254/com.example.machimanapc.howzit E/AndroidRuntime? FATAL EXCEPTION: main 
    Process: com.example.machimanapc.howzit, PID: 20254 
    java.lang.RuntimeException: Unable to start activity ComponentInfo{com.example.machimanapc.howzit/com.example.machimanapc.howzit.CommentActivity}: java.lang.NullPointerException 
      at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:2338) 
      at android.app.ActivityThread.handleLaunchActivity(ActivityThread.java:2390) 
      at android.app.ActivityThread.access$800(ActivityThread.java:151) 
      at android.app.ActivityThread$H.handleMessage(ActivityThread.java:1321) 
      at android.os.Handler.dispatchMessage(Handler.java:110) 
      at android.os.Looper.loop(Looper.java:193) 
      at android.app.ActivityThread.main(ActivityThread.java:5299) 
      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:825) 
      at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:641) 
      at dalvik.system.NativeStart.main(Native Method) 
    Caused by: java.lang.NullPointerException 
      at com.example.machimanapc.howzit.CommentActivity.onCreate(CommentActivity.java:196) 
      at android.app.Activity.performCreate(Activity.java:5264) 
      at android.app.Instrumentation.callActivityOnCreate(Instrumentation.java:1088) 
      at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:2302) 
            at android.app.ActivityThread.handleLaunchActivity(ActivityThread.java:2390) 
            at android.app.ActivityThread.access$800(ActivityThread.java:151) 
            at android.app.ActivityThread$H.handleMessage(ActivityThread.java:1321) 
            at android.os.Handler.dispatchMessage(Handler.java:110) 
            at android.os.Looper.loop(Looper.java:193) 
            at android.app.ActivityThread.main(ActivityThread.java:5299) 
            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:825) 
            at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:641) 
            at dalvik.system.NativeStart.main(Native Method) 
04-20 20:13:30.053 20254-23455/com.example.machimanapc.howzit D/dalvikvm? create interp thread : stack size=128KB 
04-20 20:13:30.053 20254-23455/com.example.machimanapc.howzit D/dalvikvm? create new thread 
04-20 20:13:30.053 20254-23455/com.example.machimanapc.howzit D/dalvikvm? new thread created 
04-20 20:13:30.053 20254-23455/com.example.machimanapc.howzit D/dalvikvm? update thread list 
04-20 20:13:30.055 20254-23457/com.example.machimanapc.howzit D/dalvikvm? threadid=14: interp stack at 0x551f9000 
04-20 20:13:30.055 20254-23457/com.example.machimanapc.howzit D/dalvikvm? init ref table 
04-20 20:13:30.055 20254-23457/com.example.machimanapc.howzit D/dalvikvm? init mutex 
04-20 20:13:30.055 20254-23457/com.example.machimanapc.howzit D/dalvikvm? threadid=14: created from interp 
04-20 20:13:30.055 20254-23455/com.example.machimanapc.howzit D/dalvikvm? start new thread 
04-20 20:13:30.055 20254-23457/com.example.machimanapc.howzit D/dalvikvm? threadid=14: notify debugger 
04-20 20:13:30.055 20254-23457/com.example.machimanapc.howzit D/dalvikvm? threadid=14 (Task.BACKGROUND_EXECUTOR-thread-13): calling run() 
04-20 20:13:30.056 20254-23457/com.example.machimanapc.howzit D/dalvikvm? create interp thread : stack size=128KB 
04-20 20:13:30.057 20254-23457/com.example.machimanapc.howzit D/dalvikvm? create new thread 
04-20 20:13:30.057 20254-23457/com.example.machimanapc.howzit D/dalvikvm? new thread created 
04-20 20:13:30.057 20254-23457/com.example.machimanapc.howzit D/dalvikvm? update thread list 
04-20 20:13:30.059 20254-23458/com.example.machimanapc.howzit D/dalvikvm? threadid=15: interp stack at 0x55219000 
04-20 20:13:30.059 20254-23458/com.example.machimanapc.howzit D/dalvikvm? init ref table 
04-20 20:13:30.059 20254-23458/com.example.machimanapc.howzit D/dalvikvm? init mutex 
04-20 20:13:30.059 20254-23458/com.example.machimanapc.howzit D/dalvikvm? threadid=15: created from interp 
04-20 20:13:30.059 20254-23457/com.example.machimanapc.howzit D/dalvikvm? start new thread 
04-20 20:13:30.059 20254-23458/com.example.machimanapc.howzit D/dalvikvm? threadid=15: notify debugger 
04-20 20:13:30.059 20254-23458/com.example.machimanapc.howzit D/dalvikvm? threadid=15 (Task.BACKGROUND_EXECUTOR-thread-14): calling run() 
04-20 20:13:30.060 20254-20272/com.example.machimanapc.howzit D/dalvikvm? create interp thread : stack size=128KB 
04-20 20:13:30.060 20254-20272/com.example.machimanapc.howzit D/dalvikvm? create new thread 
04-20 20:13:30.060 20254-20272/com.example.machimanapc.howzit D/dalvikvm? new thread created 
04-20 20:13:30.060 20254-20272/com.example.machimanapc.howzit D/dalvikvm? update thread list 
04-20 20:13:30.061 20254-23460/com.example.machimanapc.howzit D/dalvikvm? threadid=20: interp stack at 0x55239000 
04-20 20:13:30.061 20254-23460/com.example.machimanapc.howzit D/dalvikvm? init ref table 
04-20 20:13:30.061 20254-23460/com.example.machimanapc.howzit D/dalvikvm? init mutex 
04-20 20:13:30.061 20254-23460/com.example.machimanapc.howzit D/dalvikvm? threadid=20: created from interp 
04-20 20:13:30.061 20254-20272/com.example.machimanapc.howzit D/dalvikvm? start new thread 
04-20 20:13:30.061 20254-23460/com.example.machimanapc.howzit D/dalvikvm? threadid=20: notify debugger 
04-20 20:13:30.061 20254-23460/com.example.machimanapc.howzit D/dalvikvm? threadid=20 (Task.BACKGROUND_EXECUTOR-thread-15): calling run() 
04-20 20:13:31.056 20254-23455/com.example.machimanapc.howzit D/dalvikvm? threadid=12: exiting 
04-20 20:13:31.056 20254-23455/com.example.machimanapc.howzit D/dalvikvm? threadid=12: bye! 
04-20 20:13:31.060 20254-23457/com.example.machimanapc.howzit D/dalvikvm? threadid=14: exiting 
04-20 20:13:31.060 20254-23457/com.example.machimanapc.howzit D/dalvikvm? threadid=14: bye! 
04-20 20:13:31.061 20254-23458/com.example.machimanapc.howzit D/dalvikvm? threadid=15: exiting 
04-20 20:13:31.061 20254-23458/com.example.machimanapc.howzit D/dalvikvm? threadid=15: bye! 
04-20 20:13:31.064 20254-23460/com.example.machimanapc.howzit D/dalvikvm? threadid=20: exiting 
04-20 20:13:31.064 20254-23460/com.example.machimanapc.howzit D/dalvikvm? threadid=20: bye! 

`

Answer 1

ich den Fehler herausgefunden, es durch die ListView listView = (ListView) findViewById(R.id.comment_list_view) verursacht ich ListView listView = (ListView) findViewById(R.id.comment_list); Dank verwendet haben sollte.