为了查看Activity切换经历的生命周期，首先看下面代码:
布局文件
main.xml文件

<?xml version="1.0" encoding="utf-8"?>
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
    android:orientation="vertical"
    android:layout_width="fill_parent"
    android:layout_height="fill_parent"
    >
<TextView  
    android:layout_width="fill_parent" 
    android:layout_height="wrap_content" 
    android:text="@string/hello"
    />
	<Button android:text="@+id/Button01" 
			android:id="@+id/Button01"
		    android:layout_width="wrap_content"
		    android:layout_height="wrap_content"></Button>
</LinearLayout>

second.xml

<?xml version="1.0" encoding="UTF-8"?>
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"  
    android:orientation="vertical"  
    android:layout_width="fill_parent"  
    android:layout_height="wrap_content"  
    >  
    <TextView    
        android:layout_width="fill_parent"  
        android:layout_height="fill_parent"  
        >
    </TextView>  
    <Button    
        android:id="@+id/secondButton"  
        android:layout_width="fill_parent"  
        android:layout_height="fill_parent"  
        android:text="second_button"  
        />  
</LinearLayout>  

MainActivity代码

public class MainActivity extends Activity {

	private Button myButton;

	/** Called when the activity is first created. */
    @Override
    public void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.main);
        myButton=(Button)findViewById(R.id.Button01);
        myButton.setOnClickListener(new ButtonListener());
        Log.e("","MainActivity.onCreate()");
    }

    @Override
    protected void onDestroy() {
    	// TODO Auto-generated method stub
    	super.onDestroy();
    	Log.e("","MainActivity.onDestroy()");
    }
    @Override
    protected void onPause() {
    	// TODO Auto-generated method stub
    	super.onPause();
    	Log.e("","MainActivity.onPause()");
    }
    @Override
    protected void onStart() {
    	// TODO Auto-generated method stub
    	super.onStart();
    	Log.e("","MainActivity.onStart()");
    }
    @Override
    protected void onStop() {
    	// TODO Auto-generated method stub
    	super.onStop();
    	Log.e("","MainActivity.onStop()");
    }

    @Override
    protected void onRestart() {
    	// TODO Auto-generated method stub
    	super.onRestart();
    	Log.e("","MainActivity.onRestart()");
    }

    @Override
    protected void onResume() {
    	// TODO Auto-generated method stub
    	super.onResume();
    	Log.e("","MainActivity.onResume()");
    }
    class ButtonListener implements OnClickListener{
    	@Override
    	public void onClick(View v) {
    		// TODO Auto-generated method stub
    		Intent intent=new Intent();
    		intent.setClass(MainActivity.this,SecondActivity.class);
    		MainActivity.this.startActivity(intent);

    	}
    }

}

public class SecondActivity extends Activity{

	private Button secondButton;
	@Override
	protected void onCreate(Bundle savedInstanceState) {
		// TODO Auto-generated method stub
		super.onCreate(savedInstanceState);
		setContentView(R.layout.second);   
        secondButton = (Button)findViewById(R.id.secondButton);   
        secondButton.setOnClickListener(new ButtonListener());   
	}
	@Override
	protected void onStart() {
		// TODO Auto-generated method stub
		super.onStart();
		Log.e("","SecondActivity.onStart()");
	}

	@Override
	protected void onResume() {
		super.onResume();
		Log.e("","SecondActivity.onResume()");
	}
	@Override
	protected void onRestart() {
		// TODO Auto-generated method stub
		super.onRestart();
		Log.e("","SecondActivity.onReStart()");

	}	
	@Override
	protected void onStop() {
		// TODO Auto-generated method stub
		super.onStop();
		Log.e("","SecondActivity.onStop()");
	}

	@Override
	protected void onDestroy() {
		// TODO Auto-generated method stub
		super.onDestroy();
		Log.e("","SecondActivity.onDestroy()");
	}

	class ButtonListener implements OnClickListener{   
	        @Override  
	        public void onClick(View v) {   
	            // TODO Auto-generated method stub   
	            Intent intent = new Intent();   
	            intent.setClass(SecondActivity.this, MainActivity.class);   
	            SecondActivity.this.startActivity(intent);   
	        }   
	 }   

}

首先运行结果为:
MainActivity.onCreate()
MainActivity.onStart()
MainActivity.onResume()
点击按钮之后执行为
MainActivity.onPause()
SecondActivity.onCreate()
SecondActivity.onStart()
SecondActivity.onResume()
MainActivity.onStop()
从SecondActivity切换到Main会执行
SecondActivity.onPause()
MainActivity.onCreate()
MainActivity.onStart()
MainActivity.onResume()
SecondActivity.onStop()
======更改一下代码 ，将SecondActivity的一部分代码增加一行SecondActivity.this.finish();

这时运行结果为：
SecondActivity.onStop()
SecondActivity.onDestroy()


进一步修改，将MainActivity中继承的Activity修改为ActivityGroup,执行结果为：




下面看下Activity与ActivityGroup一起使用时生命周期过程
布局文件[b]main.xml[/b]

<?xml version="1.0" encoding="utf-8"?>
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
    android:orientation="vertical"
    android:layout_width="fill_parent"
    android:layout_height="fill_parent"
    >
	<LinearLayout android:id="@+id/LinearLayout01" android:layout_width="wrap_content" android:layout_height="wrap_content">
		<Button android:text="@+id/Button01" 
				android:id="@+id/Button01" 
				android:layout_width="wrap_content" 
				android:layout_height="wrap_content">
		</Button>
		<Button android:text="@+id/Button02" 
				android:id="@+id/Button02" 
				android:layout_width="wrap_content" 
				android:layout_height="wrap_content">
		</Button>
	</LinearLayout>
	<LinearLayout android:id="@+id/LinearLayout02" 
				  android:layout_width="wrap_content" 
				  android:layout_height="wrap_content">
	</LinearLayout>
</LinearLayout>

[b]listview.xml[/b]

<?xml version="1.0" encoding="UTF-8"?>
<LinearLayout android:id="@+id/LinearLayout01"     
    xmlns:android="http://schemas.android.com/apk/res/android"     
    android:layout_width="fill_parent" android:layout_height="fill_parent">     
    <ListView android:id="@+id/MyListView" android:layout_width="fill_parent"     
        android:layout_height="fill_parent">     
    </ListView>     
</LinearLayout>

[b]MainActivity[/b]

public class MainActivity extends ActivityGroup {
    private Button btn1,btn2;
    private LinearLayout container;
    /** Called when the activity is first created. */
    @Override
    public void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.main);

        container=(LinearLayout)findViewById(R.id.LinearLayout02);
        btn1=(Button)findViewById(R.id.Button01);
        btn2=(Button)findViewById(R.id.Button02);
        btn1.setOnClickListener(new ClickEvent());
        btn2.setOnClickListener(new ClickEvent());
        Log.e("Main", "MainActivity====================>onCreate");
    }

    class ClickEvent implements  OnClickListener  
    {
    	@Override
    	public void onClick(View v) {
    		// TODO Auto-generated method stub
    		container.removeAllViews();
    		Intent intent=new Intent(MainActivity.this,SubActivity.class);
    		intent.addFlags(Intent.FLAG_ACTIVITY_CLEAR_TOP);
    		String[] str=new String[12];
    		if(v==btn1)
    		{
    			 for(int i=0;i<str.length;i++)     
                     str[i]="单选"+String.valueOf(i);     
                 intent.putExtra("Name", "subActivity1");     
                 intent.putExtra("Strings", str);     
                 intent.putExtra("ChoiceMode", ListView.CHOICE_MODE_SINGLE);//通过参数设置列

    		}else if(v==btn2){

    	        for(int i=0;i<str.length;i++)     
                    str[i]="复选"+String.valueOf(i);     
                intent.putExtra("Name", "subActivity2");     
                intent.putExtra("Strings", str);     
                intent.putExtra("ChoiceMode", ListView.CHOICE_MODE_MULTIPLE);//通过参数设置列表式样     

    		}
    		 Window subActivity=getLocalActivityManager().startActivity("subActivity",intent);     
             container.addView(subActivity.getDecorView());     


    	}
    }

	@Override
	protected void onStart() {
		// TODO Auto-generated method stub
		super.onStart();
		Log.e("Main", "MainActivity====================>onStart");
	}

	@Override
	protected void onResume() {
		// TODO Auto-generated method stub
		super.onResume();
		Log.e("Main", "MainActivity====================>onResume");
	}

	@Override
	protected void onPause() {
		// TODO Auto-generated method stub
		super.onPause();
		Log.e("Main", "MainActivity====================>onPause");
	}

	@Override
	protected void onStop() {
		// TODO Auto-generated method stub
		super.onStop();
		Log.e("Main", "MainActivity====================>onStop");
	}

	@Override
	protected void onDestroy() {
		// TODO Auto-generated method stub
		super.onDestroy();
		Log.e("Main", "MainActivity====================>onDestroy");
	}

}

public class SubActivity extends Activity{
	private String name;  

	@Override
	protected void onCreate(Bundle savedInstanceState) {
		// TODO Auto-generated method stub
		super.onCreate(savedInstanceState);
		setContentView(R.layout.listview);
		 String[] str = this.getIntent().getStringArrayExtra("Strings");     
	        int choiceMode = this.getIntent().getIntExtra("ChoiceMode",     
	                ListView.CHOICE_MODE_NONE);     
	        ListView listView = (ListView) findViewById(R.id.MyListView);     

	        // 设置列表的式样     
	        int itemID = android.R.layout.simple_list_item_1;     
	        if (choiceMode == ListView.CHOICE_MODE_MULTIPLE)// 主Activity要求多选     
	            itemID = android.R.layout.simple_list_item_multiple_choice;     
	        else if (choiceMode == ListView.CHOICE_MODE_SINGLE)// 主Activity要求单选     
	            itemID = android.R.layout.simple_list_item_single_choice;     
	        ArrayAdapter<String> arrayAdapter = new ArrayAdapter<String>(this,     
	                itemID, str);     
	        listView.setAdapter(arrayAdapter);     
	        listView.setChoiceMode(choiceMode);     
	        Log.e(name, "SubActivity====================>onCreate");// 显示当前状态，onCreate与onDestroy对应     
	}

	@Override
	protected void onStart() {
		// TODO Auto-generated method stub
		super.onStart();
		Log.e(name, "SubActivity====================>onStart");
	}

	@Override
	protected void onResume() {
		// TODO Auto-generated method stub
		super.onResume();
		Log.e(name, "SubActivity====================>onResume");
	}

	@Override
	protected void onPause() {
		// TODO Auto-generated method stub
		super.onPause();
		Log.e(name, "SubActivity====================>onPause");
	}
	@Override
	protected void onStop() {
		// TODO Auto-generated method stub
		super.onStop();
		Log.e(name, "SubActivity====================>onStop");
	}
	@Override
	protected void onDestroy() {
		// TODO Auto-generated method stub
		super.onDestroy();
		Log.e(name, "SubActivity====================>onDestroy");
	}

}

运行结果如下：
MainActivity====================>onCreate
MainActivity====================>onStart
MainActivity====================>onResume
点击TAB1，执行
SubActivity====================>onCreate
SubActivity====================>onStart
SubActivity====================>onResume
切换到TAB2,执行
SubActivity====================>onPause
SubActivity====================>onStop
SubActivity====================>onDestroy
SubActivity====================>onCreate
SubActivity====================>onStart
SubActivity====================>onResume


一个更为复杂的场景如下：
1.一个主界面MainActivity(继承ActivityGroup) 点击“呼叫”按钮
进入到呼叫界面 Call（继承Activity,实现SurfaceHolder.Callback接口）
2.如果用户长时间未接电话，自动挂断并返回到MainActivity界面

进入的生命周期函数依次为
onCreate(Main)-->onStart(Main)->onResume(Main)-->onPause(Main)-->onCreate(Call)-->onStart(Call)-->onResume(Call)-->surfaceCreated(Call)-->surfaceChanged(Call)-->onStop(Main)

没有人接听，由消息事件触发：
onPause(Call)-->onDestroy(Main)-->onCreate(Main)-->onStart(Main)->onResume(Main)---->surfaceDestroyed(Call)-->onStop(Call)-->onDestroyed(Call)