学步园

一、基础知识:

1.一个Activity的生命周期图：

2.一个Activity的生命周期相关函数：

public class Activity extends ApplicationContext {
     protected void onCreate(Bundle savedInstanceState);

     protected void onStart();
     
     protected void onRestart();

     protected void onResume();

     protected void onPause();

     protected void onStop();

     protected void onDestroy();
 }

3.一个Activity的生命周期相关函数的具体介绍：

这个表格的内容非常重要，必须全部理解。

上面三部分均引用自我们安装的SDK文件夹内的文档，我引用的具体位置是:

file:///D:/Program Files/android-sdk-windows__BACK/docs/reference/android/app/Activity.html#ActivityLifecycle

 (从D:\Program Files\android-sdk-windows\docs中的offline.html文件 进入)

二、代码展示:

1."Activity_04\src\pinggle\activity_04\Activity_04.java"

package pinggle.activity_04;

import android.os.Bundle;
import android.view.View;
import android.view.View.OnClickListener;
import android.widget.Button;
import android.widget.TextView;
import android.app.Activity;
import android.content.Intent;

public class Activity_04 extends Activity {
	private TextView myFirstText;
	private Button	myButton;
	
	@Override
	protected void onCreate(Bundle savedInstanceState) {
		System.out.println(" FirstActivity -->> onCreate ... ");
		super.onCreate(savedInstanceState);
		setContentView(R.layout.activity_activity_04);
		
		//根据控件的ID来取得代表控件的对象
		myFirstText = (TextView)findViewById(R.id.myText);
		myButton = (Button)findViewById(R.id.myButton);
		
		// 为symbol和calculate设置显示的值
		myFirstText.setText(R.string.first_text);
		myButton.setText(R.string.button_text);
				
		// 将监听器的对象绑定到按钮对象上面
		myButton.setOnClickListener(new CalculateListener());
	}
	
	class CalculateListener implements OnClickListener{

		@Override
		public void onClick(View v) {
			// TODO Auto-generated method stub
			// 为另一个Activity构造Intent对象
			Intent intent = new Intent();
			intent.setClass(Activity_04.this, SecondActivity.class);
			// 使用这个Intent对象来启动SecondActivity
			Activity_04.this.startActivity(intent);
		}
		
	}
	
	@Override
	protected void onStart() {
		// TODO Auto-generated method stub
		System.out.println(" FirstActivity -->> onStart ... ");
		super.onStart();
	}
	
	@Override
	protected void onRestart() {
		// TODO Auto-generated method stub
		System.out.println(" FirstActivity -->> onRestart ... ");
		super.onRestart();
	}
	
	@Override
	protected void onResume() {
		// TODO Auto-generated method stub
		System.out.println(" FirstActivity -->> onResume ... ");
		super.onResume();
	}
	
	@Override
	protected void onPause() {
		// TODO Auto-generated method stub
		System.out.println(" FirstActivity -->> onPause ... ");
		super.onPause();
	}
	
	@Override
	protected void onStop() {
		// TODO Auto-generated method stub
		System.out.println(" FirstActivity -->> onStop ... ");
		super.onStop();
	}
	
	@Override
	protected void onDestroy() {
		// TODO Auto-generated method stub
		System.out.println(" FirstActivity -->> onDestroy ... ");
		super.onDestroy();
	}
}

2."Activity_04\src\pinggle\activity_04\SecondActivity.java"

package pinggle.activity_04;

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

public class SecondActivity extends Activity{
	private TextView mySecondText;
	
	@Override
	protected void onCreate(Bundle savedInstanceState) {
		System.out.println(" SecondActivity -->> onCreate ... ");
		super.onCreate(savedInstanceState);
		setContentView(R.layout.second);
		
		//根据控件的ID来取得代表控件的对象
		mySecondText = (TextView)findViewById(R.id.mySecondText);
		
		// 为symbol和calculate设置显示的值
		mySecondText.setText(R.string.second_text);
	}
	
	@Override
	protected void onStart() {
		// TODO Auto-generated method stub
		System.out.println(" SecondActivity -->> onStart ... ");
		super.onStart();
	}
	
	@Override
	protected void onRestart() {
		// TODO Auto-generated method stub
		System.out.println(" SecondActivity -->> onRestart ... ");
		super.onRestart();
	}
	
	@Override
	protected void onResume() {
		// TODO Auto-generated method stub
		System.out.println(" SecondActivity -->> onResume ... ");
		super.onResume();
	}
	
	@Override
	protected void onPause() {
		// TODO Auto-generated method stub
		System.out.println(" SecondActivity -->> onPause ... ");
		super.onPause();
	}
	
	@Override
	protected void onStop() {
		// TODO Auto-generated method stub
		System.out.println(" SecondActivity -->> onStop ... ");
		super.onStop();
	}
	
	@Override
	protected void onDestroy() {
		// TODO Auto-generated method stub
		System.out.println(" SecondActivity -->> onDestroy ... ");
		super.onDestroy();
	}
}

3."Activity_04\res\layout\activity_activity_04.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="fill_parent"
    >

   <TextView
       android:id="@+id/myText"
       android:layout_width="fill_parent"
       android:layout_height="wrap_content"
       android:text="@+string/hello_world"
       />

    <Button
        android:id="@+id/myButton"
        android:layout_width="fill_parent"
        android:layout_height="wrap_content"
        />
</LinearLayout>

4."Activity_04\res\layout\second.xml"

<?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:orientation="vertical" >
    
   <TextView
       android:id="@+id/mySecondText"
       android:layout_width="fill_parent"
       android:layout_height="wrap_content"
       android:text="@+string/hello_world"
       />
   
</LinearLayout>

5."Activity_04\res\values\strings.xml"

<?xml version="1.0" encoding="utf-8"?>
<resources>

    <string name="app_name">Activity_04</string>
    <string name="hello_world">Hello world!</string>
    <string name="menu_settings">Settings</string>
	<string name="first_text">这是第一个Activity！</string>
	<string name="button_text">点击，跳转到第二个Activity</string>
	<string name="second_text">这是第二个Activity！</string>
</resources>

6.“Activity_04\AndroidManifest.xml”

<?xml version="1.0" encoding="utf-8"?>
<manifest xmlns:android="http://schemas.android.com/apk/res/android"
    package="pinggle.activity_04"
    android:versionCode="1"
    android:versionName="1.0" >

    <uses-sdk
        android:minSdkVersion="4"
        android:targetSdkVersion="4" />

    <application
        android:allowBackup="true"
        android:icon="@drawable/ic_launcher"
        android:label="@string/app_name"
        android:theme="@style/AppTheme" >
        <activity
            android:name="pinggle.activity_04.Activity_04"
            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="pinggle.activity_04.SecondActivity"
            android:label="@string/second_text" >
        </activity>
    </application>

</manifest>

三、效果展示:

首先启动程序-->>

在调试信息处有如下打印语句:

然后点击按钮-->>

在调试信息处有如下打印语句:

按键盘的"返回"键-->>

在调试信息处有如下打印语句:

再按一次"返回"键，退出程序，有如下打印语句-->>

从上面的调试信息就可以看出整个Activity生命周期的流程了。。

如果想将第二个Activity的显示改为对话框的形式，只需修改"Activity_04\AndroidManifest.xml”中的如下内容:

        <activity
            android:name="pinggle.activity_04.SecondActivity"
            android:label="@string/second_text" 
            android:theme="@android:style/Theme.Dialog" >
        </activity>

 效果如下:

本文完整代码下载地址: http://download.csdn.net/detail/ypist/5140176

本文博客源地址:http://blog.csdn.net/ypist