ERROR/AndroidRuntime（219）：了java.lang.RuntimeException：無法啓動活動ComponentInfo {elf.app/elf.app.RoomInfoActivity}：java.lang.NullP

Question

logcat的：

05-18 13:35:31.954: INFO/ActivityManager(51): Starting activity: Intent { cmp=elf.app/.RoomInfoActivity (has extras) } 
05-18 13:35:32.535: WARN/ActivityManager(51): Activity pause timeout for HistoryRecord{44e19170 elf.app/.RoomListActivity} 
05-18 13:35:37.623: WARN/WindowManager(51): Key dispatching timed out sending to elf.app/elf.app.RoomListActivity 
05-18 13:35:37.623: WARN/WindowManager(51): Dispatch state: null 
05-18 13:35:37.634: WARN/WindowManager(51): Current state: {{null to Window{44e364d8 elf.app/elf.app.RoomListActivity paused=false} @ 1305725737637 lw=null lb=null fin=true gfw=true ed=true tts=0 wf=false fp=false mcf=null}} 
05-18 13:35:37.634: WARN/WindowManager(51): Continuing to wait for key to be dispatched 
05-18 13:35:37.664: WARN/WindowManager(51): No window to dispatch pointer action 0 
05-18 13:35:37.674: WARN/WindowManager(51): No window to dispatch pointer action 1 
05-18 13:35:42.018: WARN/ActivityManager(51): Launch timeout has expired, giving up wake lock! 
05-18 13:35:42.608: WARN/ActivityManager(51): Activity idle timeout for HistoryRecord{44e1eff0 elf.app/.RoomInfoActivity} 
05-18 13:35:43.434: DEBUG/dalvikvm(51): threadid=15: bogus mon 1+0>0; adjusting 
05-18 13:37:03.754: DEBUG/AndroidRuntime(219): Shutting down VM 
05-18 13:37:03.754: WARN/dalvikvm(219): threadid=3: thread exiting with uncaught exception (group=0x4001b188) 
05-18 13:37:05.425: ERROR/AndroidRuntime(219): Uncaught handler: thread main exiting due to uncaught exception 
05-18 13:37:05.554: ERROR/AndroidRuntime(219): java.lang.RuntimeException: Unable to start activity ComponentInfo{elf.app/elf.app.RoomInfoActivity}: java.lang.NullPointerException 
05-18 13:37:05.554: ERROR/AndroidRuntime(219):  at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:2496) 
05-18 13:37:05.554: ERROR/AndroidRuntime(219):  at android.app.ActivityThread.handleLaunchActivity(ActivityThread.java:2512) 
05-18 13:37:05.554: ERROR/AndroidRuntime(219):  at android.app.ActivityThread.access$2200(ActivityThread.java:119) 
05-18 13:37:05.554: ERROR/AndroidRuntime(219):  at android.app.ActivityThread$H.handleMessage(ActivityThread.java:1863) 
05-18 13:37:05.554: ERROR/AndroidRuntime(219):  at android.os.Handler.dispatchMessage(Handler.java:99) 
05-18 13:37:05.554: ERROR/AndroidRuntime(219):  at android.os.Looper.loop(Looper.java:123) 
05-18 13:37:05.554: ERROR/AndroidRuntime(219):  at android.app.ActivityThread.main(ActivityThread.java:4363) 
05-18 13:37:05.554: ERROR/AndroidRuntime(219):  at java.lang.reflect.Method.invokeNative(Native Method) 
05-18 13:37:05.554: ERROR/AndroidRuntime(219):  at java.lang.reflect.Method.invoke(Method.java:521) 
05-18 13:37:05.554: ERROR/AndroidRuntime(219):  at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:860) 
05-18 13:37:05.554: ERROR/AndroidRuntime(219):  at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:618) 
05-18 13:37:05.554: ERROR/AndroidRuntime(219):  at dalvik.system.NativeStart.main(Native Method) 
05-18 13:37:05.554: ERROR/AndroidRuntime(219): Caused by: java.lang.NullPointerException 
05-18 13:37:05.554: ERROR/AndroidRuntime(219):  at elf.app.RoomInfoActivity.onCreate(RoomInfoActivity.java:39) 
05-18 13:37:05.554: ERROR/AndroidRuntime(219):  at android.app.Instrumentation.callActivityOnCreate(Instrumentation.java:1047) 
05-18 13:37:05.554: ERROR/AndroidRuntime(219):  at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:2459) 
05-18 13:37:05.554: ERROR/AndroidRuntime(219):  ... 11 more 
05-18 13:37:05.724: INFO/Process(51): Sending signal. PID: 219 SIG: 3 
05-18 13:37:05.736: INFO/dalvikvm(219): threadid=7: reacting to signal 3 
05-18 13:37:05.736: ERROR/dalvikvm(219): Unable to open stack trace file '/data/anr/traces.txt': Permission denied 
05-18 13:37:06.025: INFO/ARMAssembler(51): generated scanline__00000077:03515104_00000000_00000000 [ 33 ipp] (47 ins) at [0x40d678:0x40d734] in 855613 ns 
05-18 13:37:06.094: INFO/ARMAssembler(51): generated scanline__00000177:03515104_00001001_00000000 [ 91 ipp] (114 ins) at [0x41eee8:0x41f0b0] in 1649122 ns 

代碼：

package elf.app; 

import elf.app.comm.CommClientMod; 
import android.app.Activity; 
import android.os.Bundle; 
import android.view.View; 
import android.view.View.OnClickListener; 
import android.widget.Button; 
import android.widget.TextView; 

    /** 
    * displays details about the selected room 
    */ 
public class RoomInfoActivity extends Activity implements OnClickListener { 
    TextView rumInfo; 
    CharSequence rumInfoText; 
    Button buttonCleaned; 
    CharSequence buttonCleanedText; 
    TextView rumStatus; 
    CharSequence rumStatusText; 

    CommClientMod comm; 
    boolean cleaned = false; 


    protected void onCreate(Bundle savedInstanceState) { 
     super.onCreate(savedInstanceState); 
     setContentView(R.layout.room_info); 

     comm = new CommClientMod("127.0.0.1", 62626); 
     rumInfo = (TextView)findViewById(R.id.textInfo); 
     buttonCleaned = (Button)findViewById(R.id.buttonCleaned); 
     rumStatus = (TextView)findViewById(R.id.textStatus); 


     rumInfoText = (CharSequence)getIntent().getExtras().getString("entry"); 
     rumInfo.setText(rumInfoText); 
     buttonCleanedText = "Färdig med städningen"; 
     buttonCleaned.setText(buttonCleanedText); 
     rumStatusText = (CharSequence)"Status: "+checkStatus(); 
     rumStatus.setText(rumStatusText); 
    } 

    public void onClick(View v) { 
     if(v.equals(buttonCleaned)) { 
      if(cleaned==false) { 
       cleaned=true; 
       comm.send("skicka meddelande rummet är städat"); 
      } 
      else { 
       cleaned=false; 
       comm.send("skicka meddelande rummet är inte städat"); 
      } 
     } 
    } 

    public String checkStatus() { 
     if(cleaned==false) 
      return "Ej städat"; 
     else 
      return "Städat"; 
    } 


} 

真的不明白，爲什麼我在這裏得到一個RuntimeException ..

Answer 1

如果從引擎收錄，它的出現buttonCleaned =（按鈕）findViewById碼匹配的行號（R.id.buttonCleaned ）;沒有找到那種觀點。它是否存在於R.layout.room_info？

Answer 2

請記住，在使用屬於該視圖的任何組件（例如按鈕）之前，必須先將setContentView（...）置於其中。否則，將引發null異常。