Activity

--http://blog.csdn.net/liuhe688/article/details/6733407

--http://bbs.51cto.com/thread-954794-1.html

public class Activity extends ApplicationContext {
      protected void onCreate(Bundle icicle);
      protected void onStart();
      protected void onRestart();
      protected void onResume();
      protected void onFreeze(Bundle outIcicle);
      protected void onPause();
      protected void onStop();
      protected void onDestroy();
}

--

package com.scott.lifecycle;

import android.app.Activity;
import android.content.Context;
import android.content.Intent;
import android.content.res.Configuration;
import android.os.Bundle;
import android.util.Log;
import android.view.View;
import android.widget.Button;


public class MainActivity extends Activity {

    private static final String TAG = "LifeCycleActivity  ...>>>生命 周期 活动";
    private Context context = this;
    private int param = 1;

    // Activity 创建时被调用
    public void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        Log.i(TAG, "onCreate called.    ---->>> Activity 创建时被调用");

        setContentView(R.layout.activity_main);

        Button btn = (Button) findViewById(R.id.button1);
        btn.setOnClickListener(new View.OnClickListener() {

            public void onClick(View v) {
                Intent intent = new Intent(context, MainActivity.class);
                startActivity(intent);
            }
        });

    }

    // Activity创建或者从后台重新回到前台时被调用
    protected void onStart() {
        super.onStart();
        Log.i(TAG, "onStart called.        ---->>> Activity创建或者从后台重新回到前台时被调用");
    }
    
    //Activity从后台重新回到前台时被调用  
    @Override  
    protected void onRestart() {  
        super.onRestart();  
        Log.i(TAG, "onRestart called.    ---->>> Activity从后台重新回到前台时被调用  ");  
    }  
      
    //Activity创建或者从被覆盖、后台重新回到前台时被调用  
    @Override  
    protected void onResume() {  
        super.onResume();  
        Log.i(TAG, "onResume called.    ---->>> Activity创建或者从被覆盖、后台重新回到前台时被调用  ");  
    }  
      
    //Activity窗口获得或失去焦点时被调用,在onResume之后或onPause之后  
    /*@Override 
    public void onWindowFocusChanged(boolean hasFocus) { 
        super.onWindowFocusChanged(hasFocus); 
        Log.i(TAG, "onWindowFocusChanged called."); 
    }*/  
      
    //Activity被覆盖到下面或者锁屏时被调用  
    @Override  
    protected void onPause() {  
        super.onPause();  
        Log.i(TAG, "onPause called.        ---->>> Activity被覆盖到下面或者锁屏时被调用  ");  
        //有可能在执行完onPause或onStop后,系统资源紧张将Activity杀死,所以有必要在此保存持久数据  
    }  
      
    //退出当前Activity或者跳转到新Activity时被调用  
    @Override  
    protected void onStop() {  
        super.onStop();  
        Log.i(TAG, "onStop called.        ---->>> 退出当前Activity或者跳转到新Activity时被调用  ");     
    }  
      
    //退出当前Activity时被调用,调用之后Activity就结束了  
    @Override  
    protected void onDestroy() {  
        super.onDestroy();  
        Log.i(TAG, "onDestory called.    ---->>> 退出当前Activity时被调用,调用之后Activity就结束了  ");  
    }  
      
    /** 
     * Activity被系统杀死时被调用. 
     * 例如:屏幕方向改变时,Activity被销毁再重建;当前Activity处于后台,系统资源紧张将其杀死. 
     * 另外,当跳转到其他Activity或者按Home键回到主屏时该方法也会被调用,系统是为了保存当前View组件的状态. 
     * 在onPause之前被调用. 
     */  
    @Override  
    protected void onSaveInstanceState(Bundle outState) {  
        outState.putInt("param", param);  
        Log.i(TAG, "onSaveInstanceState called. put param: " + param);  
        Log.i(TAG, "onSaveInstanceState called. put param:        ---->>> Activity被系统杀死时被调用. ");  
        super.onSaveInstanceState(outState);  
    }  
      
    /** 
     * Activity被系统杀死后再重建时被调用. 
     * 例如:屏幕方向改变时,Activity被销毁再重建;当前Activity处于后台,系统资源紧张将其杀死,用户又启动该Activity. 
     * 这两种情况下onRestoreInstanceState都会被调用,在onStart之后. 
     */  
    @Override  
    protected void onRestoreInstanceState(Bundle savedInstanceState) {  
        param = savedInstanceState.getInt("param");  
        Log.i(TAG, "onRestoreInstanceState called. get param: " + param);  
        Log.i(TAG, "onRestoreInstanceState called. get param:     ---->>> Activity被系统杀死后再重建时被调用. ");  
        super.onRestoreInstanceState(savedInstanceState);  
    }  
    
  //当指定了android:configChanges="orientation"后,方向改变时onConfigurationChanged被调用  
    @Override  
    public void onConfigurationChanged(Configuration newConfig) {  
        super.onConfigurationChanged(newConfig);  
        Log.i(TAG, "onConfigurationChanged called.");  
        switch (newConfig.orientation) {  
        case Configuration.ORIENTATION_PORTRAIT:  
            setContentView(R.layout.orientation_portrait);  
            break;  
        case Configuration.ORIENTATION_LANDSCAPE:  
            setContentView(R.layout.orientation_landscape);  
            break;  
        }  
    }
}