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当我打电话onClick时，为什么onCreate会崩溃Android应用程序？

2013-01-17 60 views
0

我试图加载一个新的视图，当我按下一个按钮。我有一个viewPager和按钮是在这些意见。当我打电话onClick我的应用程序永远不会启动，它会在发生任何事情之前崩溃。我一直在试图压缩这个bug一个多星期，我认为这是非常业余的东西。请帮助学生程序员！当我打电话onClick时，为什么onCreate会崩溃Android应用程序？

public class Main extends Activity { 

    Button listButton; 

    @Override 
    protected void onCreate(Bundle savedInstanceState) { 
     super.onCreate(savedInstanceState); 

     requestWindowFeature(Window.FEATURE_NO_TITLE); 
     getWindow().setFlags(WindowManager.LayoutParams.FLAG_FULLSCREEN, 
       WindowManager.LayoutParams.FLAG_FULLSCREEN); 
     setContentView(R.layout.splash); 

     SplashPager adapter = new SplashPager(); 
     ViewPager myPager = (ViewPager) findViewById(R.id.splashPager); 
     myPager.setAdapter(adapter); 
     myPager.setCurrentItem(0); 

     listButtonListener(); 
    } 

    public void listButtonListener() { 

     listButton = (Button) findViewById(R.id.splashB); 
     listButton.setOnClickListener(new OnClickListener() { 

      @Override 
      public void onClick(View arg0) { 

       setContentView(R.layout.list_layout); 

      } 

     }); 

    } 

}

日志：

01-16 20:09:49.149: W/dalvikvm(29035): threadid=1: thread exiting with uncaught exception   (group=0x40207560) 
01-16 20:09:49.149: E/AndroidRuntime(29035): FATAL EXCEPTION: main 
01-16 20:09:49.149: E/AndroidRuntime(29035): java.lang.RuntimeException: Unable to start activity ComponentInfo{com.example.survtest2/com.example.survtest2.Main}: java.lang.NullPointerException 
01-16 20:09:49.149: E/AndroidRuntime(29035): at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:1658) 
01-16 20:09:49.149: E/AndroidRuntime(29035): at android.app.ActivityThread.handleLaunchActivity(ActivityThread.java:1674) 
01-16 20:09:49.149: E/AndroidRuntime(29035): at android.app.ActivityThread.access$1500(ActivityThread.java:117) 
01-16 20:09:49.149: E/AndroidRuntime(29035): at android.app.ActivityThread$H.handleMessage(ActivityThread.java:942) 
01-16 20:09:49.149: E/AndroidRuntime(29035): at android.os.Handler.dispatchMessage(Handler.java:99) 
01-16 20:09:49.149: E/AndroidRuntime(29035): at android.os.Looper.loop(Looper.java:130) 
01-16 20:09:49.149: E/AndroidRuntime(29035): at android.app.ActivityThread.main(ActivityThread.java:3733) 
01-16 20:09:49.149: E/AndroidRuntime(29035): at java.lang.reflect.Method.invokeNative(Native Method) 
01-16 20:09:49.149: E/AndroidRuntime(29035): at java.lang.reflect.Method.invoke(Method.java:507) 
01-16 20:09:49.149: E/AndroidRuntime(29035): at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:892) 
01-16 20:09:49.149: E/AndroidRuntime(29035): at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:650) 
01-16 20:09:49.149: E/AndroidRuntime(29035): at dalvik.system.NativeStart.main(Native Method) 
01-16 20:09:49.149: E/AndroidRuntime(29035): Caused by: java.lang.NullPointerException 
01-16 20:09:49.149: E/AndroidRuntime(29035): at com.example.survtest2.Main.listButtonListener(Main.java:36) 
01-16 20:09:49.149: E/AndroidRuntime(29035): at com.example.survtest2.Main.onCreate(Main.java:30) 
01-16 20:09:49.149: E/AndroidRuntime(29035): at android.app.Instrumentation.callActivityOnCreate(Instrumentation.java:1047) 
01-16 20:09:49.149: E/AndroidRuntime(29035): at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:1622) 
01-16 20:09:49.149: E/AndroidRuntime(29035): ... 11 more 
01-16 20:09:49.149: E/AndroidRuntime(29035): [Blue Error Handler] Make Debugging Report file for main 
01-16 20:09:49.149: E/AndroidRuntime(29035): java.lang.RuntimeException: Unable to start activity ComponentInfo{com.example.survtest2/com.example.survtest2.Main}: java.lang.NullPointerException 
01-16 20:09:49.149: E/AndroidRuntime(29035): at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:1658) 
01-16 20:09:49.149: E/AndroidRuntime(29035): at android.app.ActivityThread.handleLaunchActivity(ActivityThread.java:1674) 
01-16 20:09:49.149: E/AndroidRuntime(29035): at android.app.ActivityThread.access$1500(ActivityThread.java:117) 
01-16 20:09:49.149: E/AndroidRuntime(29035): at android.app.ActivityThread$H.handleMessage(ActivityThread.java:942) 
01-16 20:09:49.149: E/AndroidRuntime(29035): at android.os.Handler.dispatchMessage(Handler.java:99) 
01-16 20:09:49.149: E/AndroidRuntime(29035): at android.os.Looper.loop(Looper.java:130) 
01-16 20:09:49.149: E/AndroidRuntime(29035): at android.app.ActivityThread.main(ActivityThread.java:3733) 
01-16 20:09:49.149: E/AndroidRuntime(29035): at java.lang.reflect.Method.invokeNative(Native Method) 
01-16 20:09:49.149: E/AndroidRuntime(29035): at java.lang.reflect.Method.invoke(Method.java:507) 
01-16 20:09:49.149: E/AndroidRuntime(29035): at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:892) 
01-16 20:09:49.149: E/AndroidRuntime(29035): at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:650) 
01-16 20:09:49.149: E/AndroidRuntime(29035): at dalvik.system.NativeStart.main(Native Method) 
01-16 20:09:49.149: E/AndroidRuntime(29035): Caused by: java.lang.NullPointerException 
01-16 20:09:49.149: E/AndroidRuntime(29035): at com.example.survtest2.Main.listButtonListener(Main.java:36) 
01-16 20:09:49.149: E/AndroidRuntime(29035): at com.example.survtest2.Main.onCreate(Main.java:30) 
01-16 20:09:49.149: E/AndroidRuntime(29035): at android.app.Instrumentation.callActivityOnCreate(Instrumentation.java:1047) 
01-16 20:09:49.149: E/AndroidRuntime(29035): at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:1622) 
01-16 20:09:49.149: E/AndroidRuntime(29035): ... 11 more

splash.xml：

<?xml version="1.0" encoding="utf-8"?> 
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android" 
    android:layout_width="match_parent" 
    android:layout_height="match_parent" 
    android:orientation="vertical" > 

<android.support.v4.view.ViewPager 
    android:id="@+id/splashPager" 
    android:layout_width="fill_parent" 
    android:layout_height="fill_parent" > 
</android.support.v4.view.ViewPager> 

</LinearLayout>

splash2.xml：

<?xml version="1.0" encoding="utf-8"?> 
<FrameLayout xmlns:android="http://schemas.android.com/apk/res/android" 
    android:layout_width="match_parent" 
    android:layout_height="match_parent" 
    android:background="#000000" 
    android:orientation="vertical" > 

    <ImageView 
     android:layout_width="wrap_content" 
     android:layout_height="wrap_content" 
     android:layout_gravity="center_horizontal" 
     android:src="@drawable/intro__1" /> 

<Button 
    android:id="@+id/splashB" 
    android:layout_width="wrap_content" 
    android:layout_height="wrap_content" 
    android:layout_gravity="bottom" 
    android:layout_marginLeft="75dp" 
    android:text="aaaaaaaaaaaaaaaaaa" /> 

</FrameLayout>

ViewPager：

@Override 
public int getCount() { 
    // TODO Auto-generated method stub 
    return 4; 
} 

@Override 
public Object instantiateItem(View collection, int position) { 
    LayoutInflater inflater = (LayoutInflater) collection.getContext() 
      .getSystemService(Context.LAYOUT_INFLATER_SERVICE); 

    int resId = 0; 
    switch (position) { 

    case 0: 
     resId = R.layout.splash2; 
     break; 
    case 1: 
     resId = R.layout.splash3; 
     break; 
    case 2: 
     resId = R.layout.splash4; 
     break; 
    case 3: 
     resId = R.layout.splash5; 
     break; 

    } 

    View view = inflater.inflate(resId, null); 
    ((ViewPager) collection).addView(view, 0); 
    return view; 

} 

@Override 
public void destroyItem(View arg0, int arg1, Object arg2) { 
    // TODO Auto-generated method stub 
    ((ViewPager) arg0).removeView((View) arg2); 
} 

@Override 
public Parcelable saveState() { 
    // TODO Auto-generated method stub 
    return null; 
} 

@Override 
public boolean isViewFromObject(View arg0, Object arg1) { 
    // TODO Auto-generated method stub 
    return arg0 == ((View) arg1); 
} 

}

来源

2013-01-17 liyicky

+0

什么代码是在第36行，你得到空指针ref？ –

+0

listButton.setOnClickListener（new OnClickListener（）{ – liyicky

+0

此外，什么在R.layout.splash？我认为它应该是专有的ViewPager。 –

回答

1

根据你的失败在listButton.setOnClickListener，我猜，R.id.splashB没有被你发现了布局。

public class Main extends Activity { 

Button listButton; 
View splash2; // Added 

@Override 
protected void onCreate(Bundle savedInstanceState) { 
    super.onCreate(savedInstanceState); 
    ... 
    setContentView(R.layout.splash); 
    SplashPager adapter = new SplashPager(); 
    ViewPager myPager = (ViewPager) findViewById(R.id.splashPager); 
    .... 
    LayoutInflater inflater = getLayoutInflater(); // Added 
    splash2 = inflater.inflate (R.layout.splash2, null); // Added 
    myPager.add (splash2); // Added 

    listButtonListener(); 
} 

public void listButtonListener() { 

    listButton = (Button) splash2.findViewById(R.id.splashB); // Changed 
    listButton.setOnClickListener(new OnClickListener() { 

     @Override 
     public void onClick(View arg0) { 
      setContentView(R.layout.list_layout); 
     } 
    }); 
}

来源

2013-01-17 01:29:20

+0

它在那里。我已经尝试了很多次。重命名了很多次。 – liyicky

+0

你可以发布你的布局？ –

+0

根据你的XML文章，你有Splash2中的按钮，但在上面的代码中，你正在加载Spash。那是你的问题。 –

0

你得到一个NullPointerException，可能是因为listButton是null。确保splashB实际上存在于splash布局中。

如果这不是答案，请尝试在listButtonListener()上设置一个断点以找出为什么它会抛出NullPointerException。

来源

2013-01-17 01:23:33 kichik

+0

是的，我已经检查了很多次，像拼写错误等简单的错误。删除listButtonListener它不会崩溃。我怎样才能做一个onClick的按钮？ – liyicky

+0

该按钮在'splash2'，但你使用'splash'与'setContentView（R.layout.splash）;' – kichik

-1

你应该尝试删除

myPager.setCurrentItem(0);

你不需要这个位置，因为在默认情况下ViewPager默认页面是0 这样你试图显示这可能不是由Android系统来创建页面。

编辑：

public class Main extends Activity { 

Button listButton; 

@Override 
protected void onCreate(Bundle savedInstanceState) { 
    super.onCreate(savedInstanceState); 

    requestWindowFeature(Window.FEATURE_NO_TITLE); 
    getWindow().setFlags(WindowManager.LayoutParams.FLAG_FULLSCREEN, 
      WindowManager.LayoutParams.FLAG_FULLSCREEN); 
    setContentView(R.layout.splash); 

    SplashPager adapter = new SplashPager(this); // PASSING MAIN ACTIVITY FOR SETTING CONTENTVIEW 
    ViewPager myPager = (ViewPager) findViewById(R.id.splashPager); 
    myPager.setAdapter(adapter); 
}...}

//你的适配器代码

@Override 
public Object instantiateItem(View collection, int position) { 
    LayoutInflater inflater = (LayoutInflater) collection.getContext() 
      .getSystemService(Context.LAYOUT_INFLATER_SERVICE); 

    int resId = 0; 
    switch (position) { 

    case 0: 
     resId = R.layout.splash2; 
     break; 
    case 1: 
     resId = R.layout.splash3; 
     break; 
    case 2: 
     resId = R.layout.splash4; 
     break; 
    case 3: 
     resId = R.layout.splash5; 
     break; 

    } 

    View view = inflater.inflate(resId, null); 
    if(resId == R.layout.splash2) { 
     Button b = (Button) view.findViewById(R.id.splashB); 
     b.setOnClickListner(new OnClickListener() { 
     @Override 
     public void onClick(View arg0) { 
      // mainActivity is Activity variable passed in Adapter constructor 
      mainActivity.setContentView(R.layout.list_layout); 

     } 
     }); 
    } 
    ((ViewPager) collection).addView(view, 0); 
    return view; 

}

来源

2013-01-17 01:26:44 PetarT

+0

它didn'不要停止崩溃，谢谢你 – liyicky

+0

这只是不是一个答案。没有理由这会导致崩溃，并说“试试这个......”没有真正的解释，这可能是如何可能是异常的原因是一个答案 – LuxuryMode

+0

解释非常简单，他不能得到按钮ListButton视图，因为它还没有被Android应用程序创建。调用setCurrentItem会尝试使用Lo广告资料不存在。 – PetarT

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