1
package com.example.Lovisis; 

import android.app.Activity; 
import android.content.Intent; 
import android.os.Bundle; 
import android.view.Menu; 
import android.view.MenuItem; 
import android.view.View; 
import android.view.View.OnClickListener; 
import android.view.animation.AccelerateInterpolator; 
import android.view.animation.Animation; 
import android.widget.Button; 

import com.yashpoolla.Lovisis.R; 

public class MainActivity extends Activity { 


    @Override 
    public void onCreate(Bundle savedInstanceState) { 
     super.onCreate(savedInstanceState); 
     setContentView(R.layout.activity_main); 

    Button a = (Button) findViewById(R.id.button3); 
    a.setOnClickListener(new OnClickListener() { 

     public void onClick(View v) { 
      //TODO Auto-generated method stub 
      gotoScreen1();//startActivity(new Intent(MainActivity.this, AlarmInput.class)); 

     } 
    }); 

    Button b = (Button) findViewById(R.id.button2); 
    b.setOnClickListener(new OnClickListener() { 

     public void onClick(View v) { 
      // TODO Auto-generated method stub 
      gotoScreen2();//startActivity(new Intent(MainActivity.this, Cbdata.class)); 
     } 
    }); 

    Button c = (Button) findViewById(R.id.button1); 
     c.setOnClickListener(new OnClickListener() { 

      public void onClick(View v) { 
       // TODO Auto-generated method stub 
       //gotoScreen4();//startActivity(new Intent(MainActivity.this, Help.class)); 
      } 
     }); 

     Button d = (Button) findViewById(R.id.Button4); 
     d.setOnClickListener(new OnClickListener() { 

      public void onClick(View v) { 
       // TODO Auto-generated method stub 
       //gotoScreen3();//startActivity(new Intent(MainActivity.this, Viewdb.class)); 
      } 
     }); 
    } 





    //anim start 



    /*public boolean onCreateOptionsMenu(Menu menu) { 
     boolean result = super.onCreateOptionsMenu(menu); 
     menu.add(0, MENU_SCREEN2, 1, R.string.menu_screen2); 
     return result; 
    } 

    public boolean onOptionsItemSelected(MenuItem item) { 
     int id = item.getItemId(); 
     switch(id) { 
     case MENU_SCREEN2: 
      gotoScreen2(); 
      break; 
     } 
     return true; 
    }*/ 

    private void gotoScreen1() { 
     View g = (View)findViewById(R.id.main); 
     applyRotation(g,0,90, new GotoNextActivity1()); 
    } 

    private void gotoScreen2() { 
     View g = (View)findViewById(R.id.main); 
     applyRotation(g,0,90, new GotoNextActivity2()); 
    } 

    private void gotoScreen3() { 
     View g = (View)findViewById(R.id.main); 
     applyRotation(g,0,90, new GotoNextActivity3()); 
    } 

    private void gotoScreen4() { 
     View g = (View)findViewById(R.id.main); 
     applyRotation(g,0,90, new GotoNextActivity4()); 
    } 

    public static void applyRotation( 
      View container, 
      float start, 
      float end, 
      Animation.AnimationListener animationListener) { 
     // Find the center of the container 
     final float centerX = container.getWidth()/2.0f; 
     final float centerY = container.getHeight()/2.0f; 

     // Create a new 3D rotation with the supplied parameter 
     // The animation listener is used to trigger the next animation 
     final Rotate3dAnimation rotation = 
       new Rotate3dAnimation(start, end, centerX, centerY, 10.0f, true); 
     rotation.setDuration(500); 
     rotation.setFillAfter(true); 
     rotation.setInterpolator(new AccelerateInterpolator()); 
     if(animationListener != null) 
      rotation.setAnimationListener(animationListener); 

     container.startAnimation(rotation); 
    } 

    private final class GotoNextActivity1 implements Animation.AnimationListener { 

     public void onAnimationStart(Animation animation) { 
     } 

     public void onAnimationEnd(Animation animation) { 
      startActivity(new Intent(MainActivity.this, AlarmInput.class)); 
      overridePendingTransition(0,0);  
     } 

     public void onAnimationRepeat(Animation animation) { 
     } 
    } 


    private final class GotoNextActivity2 implements Animation.AnimationListener { 

     public void onAnimationStart(Animation animation) { 
     } 

     public void onAnimationEnd(Animation animation) { 
      startActivity(new Intent(MainActivity.this, Cbdata.class)); 
      overridePendingTransition(0,0);  
     } 

     public void onAnimationRepeat(Animation animation) { 
     } 
    } 

    private final class GotoNextActivity3 implements Animation.AnimationListener { 

     public void onAnimationStart(Animation animation) { 
     } 

     public void onAnimationEnd(Animation animation) { 
      startActivity(new Intent(MainActivity.this, Viewdb.class)); 
      overridePendingTransition(0,0);  
     } 

     public void onAnimationRepeat(Animation animation) { 
     } 
    } 

    private final class GotoNextActivity4 implements Animation.AnimationListener { 

     public void onAnimationStart(Animation animation) { 
     } 

     public void onAnimationEnd(Animation animation) { 
      startActivity(new Intent(MainActivity.this, Help.class)); 
      overridePendingTransition(0,0);  
     } 

     public void onAnimationRepeat(Animation animation) { 
     } 
    } 
//anim end 

    } 

清单:导致空指针异常活动之间的切换

<?xml version="1.0" encoding="utf-8"?> 
<manifest xmlns:android="http://schemas.android.com/apk/res/android" 
    package="com.yashpoolla.Lovisis" 
    android:versionCode="3" 
    android:versionName="1.3" > 

    <uses-sdk 
     android:minSdkVersion="8"/> 
    <uses-permission android:name="android.permission.SEND_SMS" /> 
    <uses-permission android:name="android.permission.RECEIVE_SMS" /> 
    <uses-permission android:name="android.permission.RECEIVE_SMS" /> 
    <uses-permission android:name="android.permission.CALL_PHONE" /> 
    <uses-permission android:name="android.permission.VIBRATE"/> 
    - 

    <application 
     android:icon="@drawable/ic_launcher" 
     android:label="@string/app_name" 
     android:theme="@style/AppTheme" android:debuggable="false"> 
     <receiver android:name="com.example.Lovisis.CbReceiver" > 
      <intent-filter> 
       <action android:name="android.provider.Telephony.CB_RECEIVED" > 
       </action> 
       <action android:name="android.provider.Telephony.SMS_RECEIVED" > 
       </action> 
      </intent-filter> 
     </receiver> 

     <activity android:name="com.example.Lovisis.Cbdata" > 
      <intent-filter> 
       <action 
        android:name="android.appwidget.action.APPWIDGET_UPDATE" 
        android:launchMode="singleTop" /> 
      </intent-filter> 
     </activity> 

     <activity 
      android:name="com.example.Lovisis.MainActivity" 
      android:label="@string/title_activity_main" > 
      <intent-filter> 
       <action android:name="android.intent.action.MAIN" /> 
       <action android:name="android.provider.Telephony.CB_RECEIVED" /> 

      </intent-filter> 
     </activity> 
     <activity android:name="com.example.Lovisis.AlarmListner" /> 
     <activity android:name="com.example.Lovisis.Help" /> 
     <activity android:name="com.example.Lovisis.Viewdb" /> 
     <activity android:name="com.example.Lovisis.Sms" /> 
     <activity android:name="com.example.Lovisis.CbReceiver" /> 
     <activity android:name="com.example.Lovisis.AlarmInput" /> 
     <activity android:name="com.example.Lovisis.Manual" /> 
     <activity 
      android:name="com.example.Lovisis.AlarmAlert" 
      android:label="@string/title_activity_alarm_alert" > 
     </activity> 
     <activity android:name="com.example.Lovisis.splash"> 
      <intent-filter> 
       <action android:name="android.intent.action.MAIN" /> 
       <category android:name="android.intent.category.LAUNCHER" /> 
      </intent-filter> 
     </activity> 
    </application> 

</manifest> 

的logcat:

**04-17 15:14:26.599: D/AndroidRuntime(3024): Shutting down VM 
04-17 15:14:26.599: W/dalvikvm(3024): threadid=1: thread exiting with uncaught exception (group=0x40018578) 
04-17 15:14:26.599: E/AndroidRuntime(3024): FATAL EXCEPTION: main 
04-17 15:14:26.599: E/AndroidRuntime(3024): java.lang.NullPointerException 
04-17 15:14:26.599: E/AndroidRuntime(3024):  at com.example.Lovisis.MainActivity.applyRotation(MainActivity.java:112) 
04-17 15:14:26.599: E/AndroidRuntime(3024):  at com.example.Lovisis.MainActivity.gotoScreen1(MainActivity.java:88) 
04-17 15:14:26.599: E/AndroidRuntime(3024):  at com.example.Lovisis.MainActivity.access$0(MainActivity.java:86) 
04-17 15:14:26.599: E/AndroidRuntime(3024):  at com.example.Lovisis.MainActivity$1.onClick(MainActivity.java:29) 
04-17 15:14:26.599: E/AndroidRuntime(3024):  at android.view.View.performClick(View.java:2485) 
04-17 15:14:26.599: E/AndroidRuntime(3024):  at android.view.View$PerformClick.run(View.java:9080) 
04-17 15:14:26.599: E/AndroidRuntime(3024):  at android.os.Handler.handleCallback(Handler.java:587) 
04-17 15:14:26.599: E/AndroidRuntime(3024):  at android.os.Handler.dispatchMessage(Handler.java:92) 
04-17 15:14:26.599: E/AndroidRuntime(3024):  at android.os.Looper.loop(Looper.java:130) 
04-17 15:14:26.599: E/AndroidRuntime(3024):  at android.app.ActivityThread.main(ActivityThread.java:3687) 
04-17 15:14:26.599: E/AndroidRuntime(3024):  at java.lang.reflect.Method.invokeNative(Native Method) 
04-17 15:14:26.599: E/AndroidRuntime(3024):  at java.lang.reflect.Method.invoke(Method.java:507) 
04-17 15:14:26.599: E/AndroidRuntime(3024):  at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:867) 
04-17 15:14:26.599: E/AndroidRuntime(3024):  at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:625) 
04-17 15:14:26.599: E/AndroidRuntime(3024):  at dalvik.system.NativeStart.main(Native Method)** 

我想按钮活动之间进行切换点击上面给出的活动发生的历史,它是工作正常,突然它开始抛出空指针exception.Please帮助我。

回答

1

只是猜测,但

(View)findViewById(R.id.main); 

可能只是把它传递给​​之前返回null,然后line 112

final float centerX = container.getWidth()/2.0f; 

会抛出NullPointerException

仔细检查视图在所涉及的所有活动中存在编号main

0

对不起,实际上我为两个布局定义了相同的名称,这导致了空指针异常,无论如何感谢您的支持..