Before I ask my question I saw android intent filter? and Android: Activity not registered in the manifest also I searched this ,but I could not find my answer.
In my App,I have to start Activty1 form IntentFilterActivity(both are Activities) with implicit Intent.Here is my code:

• Manifest

  <?xml version="1.0" encoding="utf-8"?>
  <manifest xmlns:android="http://schemas.android.com/apk/res/android"
  package="com.your.namespace"
  android:versionCode="1"
  android:versionName="1.0" >
  
  <uses-sdk android:minSdkVersion="2" />
  
  <application
      android:icon="@drawable/ic_launcher"
      android:label="@string/app_name" >
      <activity
          android:label="@string/app_name"
          android:name=".IntentFilterActivity" >
          <intent-filter >
              <action android:name="android.intent.action.MAIN" />
  
              <category android:name="android.intent.category.LAUNCHER" />
          </intent-filter>
      </activity>
      <activity
          android:label="Activity1"
          android:name="com.your.namespace.Activity1" >
          <intent-filter >
              <action android:name="com.your.namespace.MY_MAIN"/>
  
              <category android:name="com.your.namespace.MY_LAUNCHER"/>
          </intent-filter>
      </activity>
  </application>
  
  </manifest>
  
  

• IntentFilterActivity

  package com.your.namespace;
  
  public class IntentFilterActivity extends Activity {
  protected String action = "com.your.namespace.MY_MAIN";
  protected String category = "com.your.namespace.MY_LAUNCHER";
  
  @Override
  public void onCreate(Bundle savedInstanceState) {
      super.onCreate(savedInstanceState);
      setContentView(R.layout.main);
      Button b1 = (Button) findViewById(R.id.button1);
      b1.setOnClickListener(new OnClickListener() {
  
          @Override
          public void onClick(View v) {
  
              Intent i = new Intent(IntentFilterActivity.this,Activity1.class);
              IntentFilterActivity.this.startActivity(i);
          }
      });
  
      Button b2 = (Button) findViewById(R.id.button2);
      b2.setOnClickListener(new OnClickListener() {
  
          @Override
          public void onClick(View v) {
              Intent i = new Intent();
              i.setAction(action);
              i.addCategory(category);
              IntentFilterActivity.this.startActivity(i);
          }
      });
  }
  }
  
  

• Activity1

  package com.your.namespace;
  
  public class Activity1 extends Activity {
  
  @Override
  public void onCreate(Bundle savedInstanceState) {
      super.onCreate(savedInstanceState);
      setContentView(R.layout.main1);
  }
  }
  
  

First I had one button(say b2) in R.layout.main and in it's onClick event I tried to start Activity1 with implicit Intent.But when I click it I get this error:

android.content.ActivityNotFoundException: No Activity found to handle Intent { act=com.your.namespace.MY_MAIN cat=[com.your.namespace.MY_LAUNCHER] }

So I added another Buuton(say b1) to R.layout.main and in it's onClick event,I tried to start Activity1 with explicit Intent and Activity1 started fine.So my problem is in about registering Activity1 in manifest.
I tried to change package name,clean/build project,creating a new project and starting from there,importing the project in eclipse on a different computer,restarting eclipse and ... but I get error.My project has only one package(com.your.namespace).
What do I do wrong?Please help me to solve this problem.
Edit:
When I change Intent filter of Activty1 to this:

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

        <category android:name="android.intent.category.LAUNCHER" />
</intent-filter>

and run App, Application's icon appears twice in Launcher!This is strange,one intent filter seems to be ignored and another filter,not.

try this:

<activity
    android:label="Activity1" android:name="com.your.namespace.Activity1" >
    <intent-filter >
        <action android:name="com.your.namespace.MY_MAIN"/>

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

notice the change: android.intent.category.DEFAULT

Should work.

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