Android：生命周期案例

　　在学习Android应用生命周期章节中，书本上写的有点笼统，较难理解。为了理解的更深，写了个程序测试一下。

　　1、在layout文件夹中建一个dialog_layout.xml

<?xml version="1.0" encoding="utf-8"?>
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"android:layout_width="match_parent"android:layout_height="match_parent"android:orientation="vertical" ><TextView android:layout_width="match_parent"android:layout_height="wrap_content"android:text="This is a dialog Activity."/></LinearLayout>

　　2、在layout文件夹中再建一个normal_layout.xml

<?xml version="1.0" encoding="utf-8"?>
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"android:layout_width="match_parent"android:layout_height="match_parent"android:orientation="vertical" ><TextView android:layout_width="match_parent"android:layout_height="wrap_content"android:text="This is a normal Activity."/></LinearLayout>

　　 3、修改layout文件夹中的activity_main.xml

<?xml version="1.0" encoding="utf-8"?>
<LinearLayoutxmlns:android="http://schemas.android.com/apk/res/android"android:orientation="vertical"android:layout_width="match_parent"android:layout_height="match_parent"><Button android:id="@+id/start_normal_activity"android:layout_width="match_parent"android:layout_height="wrap_content"android:text="Start NormalActivity"/><Button android:id="@+id/start_dialog_activity"android:layout_width="match_parent"android:layout_height="wrap_content"android:text="Start DialogActivity"/>    
</LinearLayout>

　　4、编写java文件，建立一个DialogActivity.java

package com.example.acitivitylife;import android.app.Activity;
import android.os.Bundle;public class DialogActivity extends Activity {@Overrideprotected void onCreate(Bundle savedInstanceState) {super.onCreate(savedInstanceState);setContentView(R.layout.dialog_layout);}
}

　　5、编写java文件，建立一个NormalActivity.java

package com.example.acitivitylife;import android.app.Activity;
import android.os.Bundle;public class NormalActivity extends Activity {@Overrideprotected void onCreate(Bundle savedInstanceState) {super.onCreate(savedInstanceState);setContentView(R.layout.normal_layout);}
}

　　6、修改MainActivity.java

package com.example.acitivitylife;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 MainActivity extends Activity {public static final String TAG = "MainActivity";@Overrideprotected void onCreate(Bundle savedInstanceState) {super.onCreate(savedInstanceState);Log.d(TAG, "onCreate");setContentView(R.layout.activity_main);Button startNormalActivity = (Button)findViewById(R.id.start_normal_activity);Button startDialogActivity = (Button)findViewById(R.id.start_dialog_activity);startNormalActivity.setOnClickListener(new OnClickListener() {@Overridepublic void onClick(View v) {// TODO Auto-generated method stubIntent intent = new Intent(MainActivity.this, NormalActivity.class);startActivity(intent);}});startDialogActivity.setOnClickListener(new OnClickListener() {@Overridepublic void onClick(View v) {// TODO Auto-generated method stubIntent intent = new Intent(MainActivity.this, DialogActivity.class);startActivity(intent);}});}@Overrideprotected void onStart() {super.onStart();Log.d(TAG, "OnStart");}@Overrideprotected void onResume() {super.onResume();Log.d(TAG, "onResume");}@Overrideprotected void onPause() {super.onPause();Log.d(TAG, "OnPause");}@Overrideprotected void onStop() {super.onStop();Log.d(TAG, "onStop");}@Overrideprotected void onDestroy() {super.onDestroy();Log.d(TAG, "onDestroy");}@Overrideprotected void onRestart() {super.onRestart();Log.d(TAG, "onRestart");}}

　　以上步骤完成后，安装到手机，观察LogCat打印出来的消息，对生命周期将一目了然。

　　自动安装到手机后，LogCat打印出：