Android：在onListItemClick中啓動一個intent運行時錯誤

我正在做一個帶有類似菜單的facebook的無線電項目。當菜單上的第一個項目被點擊時，應用程序應該運行myMain類，在該類中我收到無線電流。但我最近過得好logcat的這個錯誤：Android：在onListItemClick中啓動一個intent運行時錯誤

07-25 22:52:12.843: E/AndroidRuntime(9553): FATAL EXCEPTION: main 
07-25 22:52:12.843: E/AndroidRuntime(9553): java.lang.NullPointerException 
07-25 22:52:12.843: E/AndroidRuntime(9553):  at android.app.Instrumentation.execStartActivity(Instrumentation.java:1374) 
07-25 22:52:12.843: E/AndroidRuntime(9553):  at android.app.Activity.startActivityForResult(Activity.java:2827) 
07-25 22:52:12.843: E/AndroidRuntime(9553):  at android.support.v4.app.FragmentActivity.startActivityFromFragment(FragmentActivity.java:833) 
07-25 22:52:12.843: E/AndroidRuntime(9553):  at android.support.v4.app.Fragment.startActivity(Fragment.java:856) 
07-25 22:52:12.843: E/AndroidRuntime(9553):  at com.korovyansk.android.sample.slideout.MenuFragment.onListItemClick(MenuFragment.java:28) 
07-25 22:52:12.843: E/AndroidRuntime(9553):  at android.support.v4.app.ListFragment$2.onItemClick(ListFragment.java:58) 
07-25 22:52:12.843: E/AndroidRuntime(9553):  at android.widget.AdapterView.performItemClick(AdapterView.java:284) 
07-25 22:52:12.843: E/AndroidRuntime(9553):  at android.widget.ListView.performItemClick(ListView.java:3763) 
07-25 22:52:12.843: E/AndroidRuntime(9553):  at android.widget.AbsListView$PerformClick.run(AbsListView.java:1936) 
07-25 22:52:12.843: E/AndroidRuntime(9553):  at android.os.Handler.handleCallback(Handler.java:587) 
07-25 22:52:12.843: E/AndroidRuntime(9553):  at android.os.Handler.dispatchMessage(Handler.java:92) 
07-25 22:52:12.843: E/AndroidRuntime(9553):  at android.os.Looper.loop(Looper.java:123) 
07-25 22:52:12.843: E/AndroidRuntime(9553):  at android.app.ActivityThread.main(ActivityThread.java:3687) 
07-25 22:52:12.843: E/AndroidRuntime(9553):  at java.lang.reflect.Method.invokeNative(Native Method) 
07-25 22:52:12.843: E/AndroidRuntime(9553):  at java.lang.reflect.Method.invoke(Method.java:507) 
07-25 22:52:12.843: E/AndroidRuntime(9553):  at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:867) 
07-25 22:52:12.843: E/AndroidRuntime(9553):  at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:625) 
07-25 22:52:12.843: E/AndroidRuntime(9553):  at dalvik.system.NativeStart.main(Native Method)

MenuActivity類：

package com.korovyansk.android.sample.slideout; 

import android.os.Bundle; 
import android.support.v4.app.FragmentActivity; 
import android.view.KeyEvent; 

import com.korovyansk.android.slideout.SlideoutHelper; 

public class MenuActivity extends FragmentActivity{ 

    @Override 
    public void onCreate(Bundle savedInstanceState) { 
     super.onCreate(savedInstanceState); 
     mSlideoutHelper = new SlideoutHelper(this); 
     mSlideoutHelper.activate(); 
     getSupportFragmentManager().beginTransaction().add(com.korovyansk.android.slideout.R.id.slideout_placeholder, new MenuFragment(), "menu").commit(); 
     mSlideoutHelper.open(); 
    } 


    @Override 
    public boolean onKeyDown(int keyCode, KeyEvent event) { 
     if(keyCode == KeyEvent.KEYCODE_BACK){ 
      mSlideoutHelper.close(); 
      return true; 
     } 
     return super.onKeyDown(keyCode, event); 
    } 


    public SlideoutHelper getSlideoutHelper(){ 
     return mSlideoutHelper; 
    } 

    private SlideoutHelper mSlideoutHelper; 

}

MenuFragment類：

package com.korovyansk.android.sample.slideout; 

import android.content.Intent; 
import android.os.Bundle; 
import android.support.v4.app.ListFragment; 
import android.view.View; 
import android.widget.ArrayAdapter; 
import android.widget.ListView; 
import android.widget.Toast; 

public class MenuFragment extends ListFragment { 

    Intent intent; 

    @Override 
    public void onActivityCreated(Bundle savedInstanceState) { 
     super.onActivityCreated(savedInstanceState); 
     setListAdapter(new ArrayAdapter<String>(getActivity(), 
       android.R.layout.simple_list_item_1, new String[] { "Canlı Yayın", "Haberler", "Etkinlikler", " Fourth", " Fifth", " Sixth"})); 
     getListView().setCacheColorHint(0); 
    } 

    @Override 
    public void onListItemClick(ListView l, View v, int position, long id) { 
     super.onListItemClick(l, v, position, id); 
     if(position == 1) 
      intent = new Intent(getActivity().getApplicationContext(), myMain.class); 
      startActivity(intent); 
     ((MenuActivity)getActivity()).getSlideoutHelper().close(); 
    } 


}

SampleActionBarActivity類：

package com.korovyansk.android.sample.slideout; 

import android.app.Activity; 
import android.content.Intent; 
import android.os.Build; 
import android.os.Bundle; 
import android.util.TypedValue; 
import android.view.MenuItem; 
import android.widget.Toast; 

import com.korovyansk.android.slideout.SlideoutActivity; 

public class SampleActionbarActivity extends Activity { 

    @Override 
    public void onCreate(Bundle savedInstanceState) { 
     super.onCreate(savedInstanceState); 
     if(Build.VERSION.SDK_INT < Build.VERSION_CODES.HONEYCOMB){ 
      finish(); 
     } 
     setContentView(R.layout.sample_actionbar); 

    } 

    @Override 
    public boolean onOptionsItemSelected(MenuItem item) { 

     if(item.getItemId() == android.R.id.home){ 

      int width = (int)TypedValue.applyDimension(TypedValue.COMPLEX_UNIT_DIP, 40, getResources().getDisplayMetrics()); 
      SlideoutActivity.prepare(SampleActionbarActivity.this, R.id.inner_content, width); 
      startActivity(new Intent(SampleActionbarActivity.this, MenuActivity.class)); 
      overridePendingTransition(0, 0); 
     } 
     return true; 
    } 

}

SampleActivity類：

package com.korovyansk.android.sample.slideout; 

import android.annotation.TargetApi; 
import android.app.Activity; 
import android.content.Intent; 
import android.os.Build; 
import android.os.Bundle; 
import android.util.TypedValue; 
import android.view.View; 

import com.korovyansk.android.slideout.SlideoutActivity; 

public class SampleActivity extends Activity { 

    @TargetApi(11) 
    @Override 
    public void onCreate(Bundle savedInstanceState) { 
     super.onCreate(savedInstanceState); 
     setContentView(R.layout.sample); 
     if(Build.VERSION.SDK_INT >= Build.VERSION_CODES.HONEYCOMB){ 
      getActionBar().hide(); 
     } 
     findViewById(R.id.sample_button).setOnClickListener(
       new View.OnClickListener() { 
        @Override 
        public void onClick(View v) { 
         int width = (int)TypedValue.applyDimension(TypedValue.COMPLEX_UNIT_DIP, 40, getResources().getDisplayMetrics()); 
         SlideoutActivity.prepare(SampleActivity.this, R.id.inner_content, width); 
         startActivity(new Intent(SampleActivity.this, 
           MenuActivity.class)); 
         overridePendingTransition(0, 0); 
        } 
       }); 
    } 


}

而且由於誤差約爲意圖，這裏是明顯的：

<?xml version="1.0" encoding="utf-8"?> 
<manifest xmlns:android="http://schemas.android.com/apk/res/android" 
    package="com.korovyansk.android.sample.slideout" 
    android:versionCode="1" 
    android:versionName="1.0" > 

    <uses-sdk android:minSdkVersion="7" 
     android:targetSdkVersion="11" /> 

    <application android:theme="@style/AppTheme" 
     android:icon="@drawable/ic_launcher" 
     android:label="@string/app_name" > 
     <activity 
      android:label="Simple Sample" 
      android:name=".SampleActivity" > 
      <intent-filter > 
       <action android:name="android.intent.action.MAIN" /> 
       <category android:name="android.intent.category.LAUNCHER" /> 
      </intent-filter> 
     </activity> 
     <activity 
      android:label="@string/app_name" 
      android:name=".MenuActivity" 
      android:theme="@style/MenuTheme" > 
     </activity> 
     <activity android:name=".SampleActionbarActivity" 
      android:label="Sample With Actionbar"> 
      <intent-filter > 
       <action android:name="android.intent.action.MAIN" /> 
       <category android:name="android.intent.category.LAUNCHER" /> 
      </intent-filter> 
     </activity> 
     <activity android:name=".myMain" 
      android:label="@string/app_name"> 
     </activity> 
    </application> 
</manifest>

來源

2013-07-25 user2604150

嘗試刪除'.getApplicationContext（）'從那裏您創建'Intent' – codeMagic

@codeMagic我應該寫什麼，而不是.getApplicationContext（）？因爲沒有任何意圖構造函數（c類） – user2604150

請參閱我的答案... – codeMagic

假設這行是第28 MenuFragment

intent = new Intent(getActivity().getApplicationContext(), myMain.class);

將其更改爲

intent = new Intent(getActivity(), myMain.class);

Activity都有自己Context所以通過調用getActivity()你獲得了Context

來源

2013-07-25 20:14:02 codeMagic

非常感謝，現在它正在工作。 – user2604150

不客氣。請點擊複選標記以接受正確的答案，這樣可以幫助他人更輕鬆 – codeMagic

Android：在onListItemClick中啓動一個intent運行時錯誤

回答

相關問題