java.lang.RuntimeException：无法启动活动ComponentInfo

我知道这个错误出现在论坛上数百万次，但请帮我找到我错过的东西。我试图做简单的标签导向的应用程序，我没有太多的（除非错误）java.lang.RuntimeException：无法启动活动ComponentInfo

1）我的主要活动是基于tablayout教程我发现了什么

public class MainTabPanel extends TabActivity { 

    public void onCreate(Bundle savedInstanceState) { 
     super.onCreate(savedInstanceState); 
     setContentView(R.layout.mainlayout); 
     Resources res = getResources(); 
     TabHost tabHost = getTabHost(); 
     TabHost.TabSpec spec; 
     Intent intent; 
     intent = new Intent().setClass(this, MyBookActivity.class); 
     spec = tabHost.newTabSpec("main") 
       .setIndicator("Main", res.getDrawable(R.drawable.ic_mybook)) 
       .setContent(intent); 
     tabHost.addTab(spec); 
     tabHost.setCurrentTab(0); 
    } 

}

2）mainlayout。 XML

<?xml version="1.0" encoding="utf-8"?> 
<TabHost xmlns:android="http://schemas.android.com/apk/res/android" 
android:id="@android:id/tabhost" 
android:layout_width="fill_parent" 
android:layout_height="fill_parent"> 
<LinearLayout 
    android:orientation="vertical" 
    android:layout_width="fill_parent"  
    android:layout_height="fill_parent"   
    android:padding="5dp"> 
<TabWidget 
    android:id="@android:id/tabs" 
    android:layout_width="fill_parent" 
    android:layout_height="wrap_content" />   

    <FrameLayout  
    android:id="@android:id/tabcontent" 
    android:layout_width="fill_parent" 
    android:layout_height="fill_parent" 
    android:padding="5dp" /> 
</LinearLayout></TabHost>

3）我的第二个活动是基本上几乎是空的，它;只是显示当前日期和时间，工作之前，我尝试添加标签面板

4）我的清单文件

<?xml version="1.0" encoding="utf-8"?> 
<manifest xmlns:android="http://schemas.android.com/apk/res/android" 
    package="org.th.mybook" 
    android:versionCode="1" 
    android:versionName="1.0" > 
    <uses-sdk android:minSdkVersion="8" /> 
    <application 
     android:icon="@drawable/ic_launcher" 
     android:label="@string/app_name" > 
     <activity 
      android:name=".MainTabPanel" 
      android:label="@string/app_name" > 
      <intent-filter> 
       <action android:name="android.intent.action.MAIN" /> 
       <category android:name="android.intent.category.LAUNCHER" /> 
      </intent-filter> 
     </activity> 
     <activity 
      android:name="MyBookActivity" 
      android:label="@string/app_name" > 
      <intent-filter> 
       <action android:name="android.intent.action.MAIN" /> 
       <category android:name="android.intent.category.ALTERNATIVE" /> 
      </intent-filter> 
     </activity> 
    </application> 
</manifest>

5日志猫错误

02-10 21:04:45.203: E/AndroidRuntime(1107): FATAL EXCEPTION: main 
02-10 21:04:45.203: E/AndroidRuntime(1107): java.lang.RuntimeException: Unable to start activity ComponentInfo{org.th.mybook/org.th.mybook.MainTabPanel}: java.lang.RuntimeException: Unable to instantiate activity ComponentInfo{org.th.mybook/org.th.mybook.MyBookActivity}: java.lang.NullPointerException 
02-10 21:04:45.203: E/AndroidRuntime(1107):  at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:2663) 
02-10 21:04:45.203: E/AndroidRuntime(1107):  at android.app.ActivityThread.handleLaunchActivity(ActivityThread.java:2679) 
02-10 21:04:45.203: E/AndroidRuntime(1107):  at android.app.ActivityThread.access$2300(ActivityThread.java:125) 
02-10 21:04:45.203: E/AndroidRuntime(1107):  at android.app.ActivityThread$H.handleMessage(ActivityThread.java:2033) 
02-10 21:04:45.203: E/AndroidRuntime(1107):  at android.os.Handler.dispatchMessage(Handler.java:99) 
02-10 21:04:45.203: E/AndroidRuntime(1107):  at android.os.Looper.loop(Looper.java:123) 
02-10 21:04:45.203: E/AndroidRuntime(1107):  at android.app.ActivityThread.main(ActivityThread.java:4627) 
02-10 21:04:45.203: E/AndroidRuntime(1107):  at java.lang.reflect.Method.invokeNative(Native Method) 
02-10 21:04:45.203: E/AndroidRuntime(1107):  at java.lang.reflect.Method.invoke(Method.java:521) 
02-10 21:04:45.203: E/AndroidRuntime(1107):  at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:868) 
02-10 21:04:45.203: E/AndroidRuntime(1107):  at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:626) 
02-10 21:04:45.203: E/AndroidRuntime(1107):  at dalvik.system.NativeStart.main(Native Method) 
02-10 21:04:45.203: E/AndroidRuntime(1107): Caused by: java.lang.RuntimeException: Unable to instantiate activity ComponentInfo{org.th.mybook/org.th.mybook.MyBookActivity}: java.lang.NullPointerException 
02-10 21:04:45.203: E/AndroidRuntime(1107):  at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:2585) 
02-10 21:04:45.203: E/AndroidRuntime(1107):  at android.app.ActivityThread.startActivityNow(ActivityThread.java:2503) 
02-10 21:04:45.203: E/AndroidRuntime(1107):  at android.app.LocalActivityManager.moveToState(LocalActivityManager.java:127) 
02-10 21:04:45.203: E/AndroidRuntime(1107):  at android.app.LocalActivityManager.startActivity(LocalActivityManager.java:339) 
02-10 21:04:45.203: E/AndroidRuntime(1107):  at android.widget.TabHost$IntentContentStrategy.getContentView(TabHost.java:651) 
02-10 21:04:45.203: E/AndroidRuntime(1107):  at android.widget.TabHost.setCurrentTab(TabHost.java:323) 
02-10 21:04:45.203: E/AndroidRuntime(1107):  at android.widget.TabHost.addTab(TabHost.java:213) 
02-10 21:04:45.203: E/AndroidRuntime(1107):  at org.th.mybook.MainTabPanel.onCreate(MainTabPanel.java:30) 
02-10 21:04:45.203: E/AndroidRuntime(1107):  at android.app.Instrumentation.callActivityOnCreate(Instrumentation.java:1047) 
02-10 21:04:45.203: E/AndroidRuntime(1107):  at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:2627) 
02-10 21:04:45.203: E/AndroidRuntime(1107):  ... 11 more 
02-10 21:04:45.203: E/AndroidRuntime(1107): Caused by: java.lang.NullPointerException 
02-10 21:04:45.203: E/AndroidRuntime(1107):  at android.content.ContextWrapper.getApplicationContext(ContextWrapper.java:100) 
02-10 21:04:45.203: E/AndroidRuntime(1107):  at org.th.mybook.MyBookActivity.<init>(MyBookActivity.java:16) 
02-10 21:04:45.203: E/AndroidRuntime(1107):  at java.lang.Class.newInstanceImpl(Native Method) 
02-10 21:04:45.203: E/AndroidRuntime(1107):  at java.lang.Class.newInstance(Class.java:1429) 
02-10 21:04:45.203: E/AndroidRuntime(1107):  at android.app.Instrumentation.newActivity(Instrumentation.java:1021) 
02-10 21:04:45.203: E/AndroidRuntime(1107):  at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:2577) 
02-10 21:04:45.203: E/AndroidRuntime(1107):  ... 20 more

请帮帮我，告诉我，我错过了，即时通讯比较该代码与我的旧的，我无法找到任何东西问候

6）我的书活动

public class MyBookActivity extends Activity { 
    java.text.DateFormat dateFormat = android.text.format.DateFormat.getDateFormat(getApplicationContext()); 

    @Override 
    public void onCreate(Bundle savedInstanceState) { 
     super.onCreate(savedInstanceState); 
     setContentView(R.layout.main); 
     DigitalClock clock = (DigitalClock) findViewById(R.id.digitalClock1); 
     final TextView date = (TextView) findViewById(R.id.textView1); 
     date.setText(dateFormat.format(new Date())); 
     TextWatcher watcher = new TextWatcher() { 

      @Override 
      public void afterTextChanged(Editable s) { 
      } 

      @Override 
      public void beforeTextChanged(CharSequence s, int start, int count, 
        int after) { 
      } 

      @Override 
      public void onTextChanged(CharSequence s, int start, int before, 
        int count) { 

       if (s.toString().startsWith("00:00:00") 
         || s.toString().startsWith("12:00:00")) { 
        date.setText(dateFormat.format(new Date())); 
       } 
      } 
     }; 
     clock.addTextChangedListener(watcher); 

    } 
}

7）main.xml中的布局 - >˚F或者我的书活动

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


    <LinearLayout 
     android:id="@+id/DatePanel1" 
     android:layout_width="wrap_content" 
     android:layout_height="wrap_content" > 


     <TextView 
      android:id="@+id/textView1" 
      android:layout_width="match_parent" 
      android:layout_height="wrap_content" 
      android:layout_marginRight="@dimen/space" 
      android:layout_weight="1" 
      android:text="TextView" /> 

     <DigitalClock 
      android:id="@+id/digitalClock1" 
      android:layout_width="0dp" 
      android:layout_height="wrap_content" 
      android:layout_weight="1" 
      android:text="DigitalClock" /> 
    </LinearLayout> 

</LinearLayout>

来源

2012-03-27 user902383

您是否实施了MyBookActivity？ – jpm 2012-03-27 22:14:47

是的，请发布代码为“MyBookActivity”，如果你还没有实现它，然后实现它，这将解决您的问题。 – Mayank 2012-03-27 22:20:01

正如我所说我没有在这里添加，因为它工作之前我添加标签，但现在我张贴代码+布局文件 – user902383 2012-03-28 06:08:14

这是我自己的愚蠢：

java.text.DateFormat dateFormat = android.text.format.DateFormat.getDateFormat(getApplicationContext());

把这个位onCreate方法内固定我的问题

感谢大家的帮助

来源

2012-03-28 19:24:59 user902383

<activity 
     android:name="MyBookActivity" 
     android:label="@string/app_name" > 
     <intent-filter> 
      <action android:name="android.intent.action.MAIN" /> 
      <category android:name="android.intent.category.ALTERNATIVE" /> 
     </intent-filter> 
    </activity>

哪里是MyBookActivity之前你点？

来源

2012-03-27 22:25:13

我会检查，但我不认为这是问题，我检查了一个工作示例，并且点只在主要活动之前 – user902383 2012-03-28 06:14:17

你Manifest必须更改等确定像".YourActivityname"这个活动的名称必须

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

<uses-sdk 
    android:minSdkVersion="8" android:targetSdkVersion="8" /> 

<application 
    android:icon="@drawable/ic_launcher" 
    android:label="@string/app_name" > 
    <activity 
     android:name=".MainTabPanel" 
     android:label="@string/app_name" > 
     <intent-filter> 
      <action android:name="android.intent.action.MAIN" /> 
      <category android:name="android.intent.category.LAUNCHER" /> 
     </intent-filter> 
    </activity> 
    <activity 
     android:name=".MyBookActivity" >    
    </activity> 
</application>

来源

2012-08-28 12:09:50 NagarjunaReddy

我有同样的问题，我清理和重建项目，它的工作。

来源

2018-02-13 06:46:52 Pavel

java.lang.RuntimeException：无法启动活动ComponentInfo

回答

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