使用意图启动新活动时发生活动未发现异常

Question

我正在使用线程概念，即当我的应用程序加载它时，显示图片3秒，然后加载活动。 但我得到一个活动未发现异常

WelcomeScreen-1活性（负载并停留3secs） MainActivity-2号活性的SHLD开始计时后。（抛出错误说不幸的是停止）。 我对Android完全陌生，这是我第一个应用程序。请不要重复。 由于提前

WelcomeScreen代码：

public class WelcomeScreen extends Activity{ 

    @Override 
    protected void onCreate(Bundle savedInstanceState) { 
     // TODO Auto-generated method stub 
     super.onCreate(savedInstanceState); 
     setContentView(R.layout.welcomescreen); 
     Thread thread=new Thread(){ 
      public void run(){ 
       try{ 
        sleep(3000); 
       }catch(InterruptedException e){ 
        e.printStackTrace(); 
       }finally{ 
        Intent startMainActivity = new Intent("com.thenewboston.helloworld.MainActivity"); 
        startActivity(startMainActivity); 
       } 
      } 
     };thread.start(); 

    } 


} 

MainActivity代码：

public class MainActivity extends ActionBarActivity { 


    int counter; 
    Button add, sub; 
    TextView displayTxt; 
    @Override 
    protected void onCreate(Bundle savedInstanceState) { 
     super.onCreate(savedInstanceState); 
     setContentView(R.layout.activity_main); 
     counter=0; 
     add=(Button) findViewById(R.id.addButton); 
     sub=(Button) findViewById(R.id.subButton); 
     displayTxt=(TextView) findViewById(R.id.textView1); 
     add.setOnClickListener(new View.OnClickListener(

       ) { 

     @Override 
     public void onClick(View v) { 
      // TODO Auto-generated method stub 
      counter++; 
      displayTxt.setText("Your Count is "+counter); 
     } 
    }); 
     sub.setOnClickListener(new View.OnClickListener() { 

     @Override 
     public void onClick(View v) { 
      // TODO Auto-generated method stub 
      counter--; 
      displayTxt.setText("Your Count is "+counter); 
     } 
    }); 


    } 

Android清单：

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

    <uses-sdk 
     android:minSdkVersion="8" 
     android:targetSdkVersion="19" /> 

    <application 
     android:allowBackup="true" 
     android:icon="@drawable/ic_launcher" 
     android:label="@string/app_name" 
     android:theme="@style/AppTheme" > 
     <activity 
      android:name="com.thenewboston.helloworld.WelcomeScreen" 
      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="com.thenewboston.helloworld.MainActivity" 
      android:label="@string/app_name" > 

      <intent-filter> 
       <action android:name="android.intent.action.MAIN" /> 

       <category android:name="android.intent.category.DEFAULT" /> 
      </intent-filter> 
     </activity> 
    </application> 

</manifest> 

logcat的日志：

11-08 12:55:03.172: D/dalvikvm(1994): GC_FOR_ALLOC freed 58K, 5% free 2891K/3032K, paused 58ms, total 61ms 
11-08 12:55:03.172: I/dalvikvm-heap(1994): Grow heap (frag case) to 8.050MB for 5404816-byte allocation 
11-08 12:55:03.242: D/dalvikvm(1994): GC_FOR_ALLOC freed 2K, 2% free 8166K/8312K, paused 63ms, total 63ms 
11-08 12:55:04.462: D/gralloc_goldfish(1994): Emulator without GPU emulation detected. 
11-08 12:55:07.152: W/dalvikvm(1994): threadid=11: thread exiting with uncaught exception (group=0xb2a9aba8) 
11-08 12:55:07.172: E/AndroidRuntime(1994): FATAL EXCEPTION: Thread-129 
11-08 12:55:07.172: E/AndroidRuntime(1994): Process: com.thenewboston.helloworld, PID: 1994 
11-08 12:55:07.172: E/AndroidRuntime(1994): android.content.ActivityNotFoundException: No Activity found to handle Intent { act=com.thenewboston.helloworld.MAINACTIVITY } 
11-08 12:55:07.172: E/AndroidRuntime(1994):  at android.app.Instrumentation.checkStartActivityResult(Instrumentation.java:1632) 
11-08 12:55:07.172: E/AndroidRuntime(1994):  at android.app.Instrumentation.execStartActivity(Instrumentation.java:1424) 
11-08 12:55:07.172: E/AndroidRuntime(1994):  at android.app.Activity.startActivityForResult(Activity.java:3424) 
11-08 12:55:07.172: E/AndroidRuntime(1994):  at android.app.Activity.startActivityForResult(Activity.java:3385) 
11-08 12:55:07.172: E/AndroidRuntime(1994):  at android.app.Activity.startActivity(Activity.java:3627) 
11-08 12:55:07.172: E/AndroidRuntime(1994):  at android.app.Activity.startActivity(Activity.java:3595) 
11-08 12:55:07.172: E/AndroidRuntime(1994):  at com.thenewboston.helloworld.WelcomeScreen$1.run(WelcomeScreen.java:22) 

Answer 1

而不是你的意图使用该

新的意图（WelcomeScreen.this，MainActivity.class）的;

Answer 2

这个问题的答案可能是

Intent startMainActivity = new Intent(this,MainActivity.class); 

我认为这将有助于

Answer 3

您应指定要在清单中不是设置为启动这样的默认活动：

<activity 
    android:name=".MainActivity" 
    android:label="@string/app_name" > 
</activity> 

然后你就可以简单地开始了新的活动

startActivity(new Intent(this,MainActivity.class));