Activity的LifeCycle

ActivityA.java代码：

package com.lau.lifecycle;

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

public class ActivityA extends Activity {
    private String TAG = "DEBUG";

    private Button btn;

    /** Called when the activity is first created. */
    @Override
    public void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.main);
        btn = (Button) findViewById(R.id.btn_a);
        btn.setOnClickListener(new OnClickListener() {
            @Override
            public void onClick(View v) {
                Intent intent = new Intent();
                intent.setClass(ActivityA.this, ActivityB.class);
                startActivity(intent);
            }
        });
        Log.d(TAG , "ACTIVITY A----onCreate");
    }

    @Override
    protected void onStart() {
        super.onStart();
        Log.d(TAG , "ACTIVITY A----onStart");
    }

    @Override
    protected void onRestart() {
        super.onRestart();
        Log.d(TAG , "ACTIVITY A----onRestart");
    }

    @Override
    protected void onResume() {
        super.onResume();
        Log.d(TAG , "ACTIVITY A----onResume");
    }

    @Override
    protected void onPause() {
        super.onPause();
        Log.d(TAG , "ACTIVITY A----onPause");
    }

    @Override
    protected void onStop() {
        super.onStop();
        Log.d(TAG , "ACTIVITY A----onStop");
    }

    @Override
    protected void onDestroy() {
        super.onDestroy();
        Log.d(TAG , "ACTIVITY A----onDestroy");
    }
}

ActivityB.java代码：

package com.lau.lifecycle;

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

public class ActivityB extends Activity{
    private String TAG = "DEBUG";
    private Button btn;

    /** Called when the activity is first created. */
    @Override
    public void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.layout_b);
        btn = (Button) findViewById(R.id.btn_b);
        btn.setOnClickListener(new OnClickListener() {
            @Override
            public void onClick(View v) {
                Intent intent = new Intent();
                intent.setClass(ActivityB.this, ActivityA.class);
                startActivity(intent);
            }
        });
        Log.d(TAG , "ACTIVITY B----onCreate");
    }

    @Override
    protected void onStart() {
        super.onStart();
        Log.d(TAG , "ACTIVITY B----onStart");
    }

    @Override
    protected void onRestart() {
        super.onRestart();
        Log.d(TAG , "ACTIVITY B----onRestart");
    }

    @Override
    protected void onResume() {
        super.onResume();
        Log.d(TAG , "ACTIVITY B----onResume");
    }

    @Override
    protected void onPause() {
        super.onPause();
        Log.d(TAG , "ACTIVITY B----onPause");
    }

    @Override
    protected void onStop() {
        super.onStop();
        Log.d(TAG , "ACTIVITY B----onStop");
    }

    @Override
    protected void onDestroy() {
        super.onDestroy();
        Log.d(TAG , "ACTIVITY B----onDestroy");
    }
}

当启动该app时的打印信息为：

03-07 01:25:47.741: DEBUG/DEBUG(431): ACTIVITY A----onCreate
03-07 01:25:47.741: DEBUG/DEBUG(431): ACTIVITY A----onStart
03-07 01:25:47.751: DEBUG/DEBUG(431): ACTIVITY A----onResume

点击了ActivityA的按钮后的打印信息为：

03-07 01:28:20.581: DEBUG/DEBUG(431): ACTIVITY A----onPause
03-07 01:28:20.631: DEBUG/DEBUG(431): ACTIVITY B----onCreate
03-07 01:28:20.631: DEBUG/DEBUG(431): ACTIVITY B----onStart
03-07 01:28:20.631: DEBUG/DEBUG(431): ACTIVITY B----onResume
03-07 01:28:21.001: DEBUG/DEBUG(431): ACTIVITY A----onStop

进入ActivityB后按下键盘"Esc"后的打印信息：

03-07 01:32:16.251: DEBUG/DEBUG(431): ACTIVITY B----onPause
03-07 01:32:16.281: DEBUG/DEBUG(431): ACTIVITY A----onRestart
03-07 01:32:16.281: DEBUG/DEBUG(431): ACTIVITY A----onStart
03-07 01:32:16.281: DEBUG/DEBUG(431): ACTIVITY A----onResume
03-07 01:32:16.641: DEBUG/DEBUG(431): ACTIVITY B----onStop
03-07 01:32:16.641: DEBUG/DEBUG(431): ACTIVITY B----onDestroy