Android應用崩潰時我使用許多按鈕點擊

Question

public class App2Activity extends Activity implements OnClickListener { 

    Button button; 
    Button button2; 
    Button button3; 
    Button button4; 
    Button button5; 

    @Override 
    public void onCreate(Bundle savedInstanceState) { 
     super.onCreate(savedInstanceState); 
     setContentView(R.layout.main2); 
     button=(Button) findViewById(R.id.button1); 
     button2=(Button) findViewById(R.id.button2); 
     button3=(Button) findViewById(R.id.button3); 
     button4=(Button) findViewById(R.id.button4); 
     button5=(Button) findViewById(R.id.button5); 
     button.setOnClickListener(this); 
     button2.setOnClickListener(this); 
     button3.setOnClickListener(this); 
     button4.setOnClickListener(this); 
     button5.setOnClickListener(this);  
    }//End oncreate  

    @Override 
    public void onClick(View v){ 

     switch(v.getId()){ 

     case R.id.button1: 
      Intent intent=new Intent(this,MainActivity.class); 
      this.startActivity(intent); 
      break; 

     case R.id.button2: 
      Intent intent2=new Intent(this,PollaplasiasmosActivity.class); 
      this.startActivity(intent2); 
      break; 


     case R.id.button3: 
      Intent intent3=new Intent(this,AfairesiActivity.class); 
      this.startActivity(intent3); 
      break; 


     case R.id.button4: 
      Intent intent4=new Intent(this,MaxActivity.class); 
      this.startActivity(intent4); 
      break; 

     case R.id.button5: 
      Intent intent5=new Intent(this,MinActivity.class); 
      this.startActivity(intent5); 
      break; 

     } 
    } 
} 

而Logcat是如下

05-25 23:11:45.878 8451 8451 D  skia   jpeg_decoder mode 1, config 6, w 1667, h 1667, sample 1, bsLength 9ff28!! 
05-25 23:20:31.254 11279 11279 D skia   jpeg_decoder mode 1, config 6, w 1667, h 1667, sample 1, bsLength 9ff28!! 
05-25 23:20:31.748 11279 11279 E AndroidRuntime FATAL EXCEPTION: main 
05-25 23:20:31.748 11279 11279 E AndroidRuntime java.lang.RuntimeException: Unable to start activity ComponentInfo{com.mycompany.myapp3/com.mycompany.myapp3.App2Activity}: java.lang.NullPointerException 
05-25 23:20:31.748 11279 11279 E AndroidRuntime at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:2372) 
05-25 23:20:31.748 11279 11279 E AndroidRuntime at android.app.ActivityThread.handleLaunchActivity(ActivityThread.java:2424) 
05-25 23:20:31.748 11279 11279 E AndroidRuntime at android.app.ActivityThread.access$600(ActivityThread.java:162) 
05-25 23:20:31.748 11279 11279 E AndroidRuntime at android.app.ActivityThread$H.handleMessage(ActivityThread.java:1364) 
05-25 23:20:31.748 11279 11279 E AndroidRuntime at android.os.Handler.dispatchMessage(Handler.java:107) 
05-25 23:20:31.748 11279 11279 E AndroidRuntime at android.os.Looper.loop(Looper.java:194) 
05-25 23:20:31.748 11279 11279 E AndroidRuntime at android.app.ActivityThread.main(ActivityThread.java:5400) 
05-25 23:20:31.748 11279 11279 E AndroidRuntime at java.lang.reflect.Method.invokeNative(Native Method) 
05-25 23:20:31.748 11279 11279 E AndroidRuntime at java.lang.reflect.Method.invoke(Method.java:525) 
05-25 23:20:31.748 11279 11279 E AndroidRuntime at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:837) 
05-25 23:20:31.748 11279 11279 E AndroidRuntime at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:604) 
05-25 23:20:31.748 11279 11279 E AndroidRuntime at dalvik.system.NativeStart.main(Native Method) 
05-25 23:20:31.748 11279 11279 E AndroidRuntime Caused by: java.lang.NullPointerException 
05-25 23:20:31.748 11279 11279 E AndroidRuntime at com.mycompany.myapp3.App2Activity.onCreate(App2Activity.java:63) 
05-25 23:20:31.748 11279 11279 E AndroidRuntime at android.app.Activity.performCreate(Activity.java:5122) 
05-25 23:20:31.748 11279 11279 E AndroidRuntime at android.app.Instrumentation.callActivityOnCreate(Instrumentation.java:1081) 
05-25 23:20:31.748 11279 11279 E AndroidRuntime at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:2336) 
05-25 23:20:31.748 11279 11279 E AndroidRuntime ... 11 more 

代碼的第一部分是主Activity其中I具有導致其他活動的按鈕。第二部分代碼是Logcat。關鍵是我的應用程序沒有錯誤，但它崩潰。你能推薦我任何解決方案，因爲我嘗試了很多其他選擇。謝謝。

在main2.xml我根據你的觀察

<Button 
    android:id="@+id/button4" 
    android:layout_width="wrap_content" 
    android:layout_height="wrap_content" 
    android:layout_alignParentLeft="true" 
    android:layout_below="@+id/button3" 
    android:drawableTop="@drawable/cat" 
    android:text="" 
    android:color="#66CCFF" /> 

Answer 1

你得到的線NPE沒有63

Caused by: java.lang.NullPointerException 
at com.mycompany.myapp3.App2Activity.onCreate(App2Activity.java:63) 

您的按鈕沒有被分配給對象基準固定代碼 -

findViewById(R.id.b4); 

返回null;