package com.yy.twoactivity;

import android.app.Activity;
import android.content.Intent;
import android.os.Bundle;
import android.view.View;

public class MainActivity extends Activity {

  @Override
  protected void onCreate(Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);
    setContentView(R.layout.activity_main);
  }
  
  /**
   * 點擊事件，當用戶點擊的時候跳轉到第二個界面
   * @param view
   */
  public void click(View view){
    //意圖
    Intent intent=new Intent();
    //設置包和界面
    intent.setClassName(this, "com.yy.twoactivity.SecondActivity");
    //跳轉到新的設定好的界面
    startActivity(intent);
  }
  
  /**
   * 點擊事件，激活系統(tǒng)的應用 程序界面
   * @param view
   */
  public void click2(View view){
    //意圖
    Intent intent=new Intent();
    //設置預打開系統(tǒng)應用的包和界面
    // cmp=com.android.gallery/com.android.camera.GalleryPicker 
    intent.setClassName("com.android.gallery", "com.android.camera.GalleryPicker");
    //跳轉到新的設定好的界面
    startActivity(intent);
  }
}

package com.yy.twoactivity;

import android.app.Activity;
import android.os.Bundle;

public class SecondActivity extends Activity {
  @Override
  protected void onCreate(Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);
    setContentView(R.layout.activity2);
  }
}

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