Activity声明周期1

oncreate():在Activity对象第一次创建时调用

onStart():当Activity变得可见时调用该函数

onResume():当Activity开始准备于用户交互时调用该方法（即获得焦点）

onpause():当系统即将启动另外一个Activity时调用该函数

onstop():当Activity变得不可见时调用该函数

onDestroy();当Activity被销毁之前将会调用该函数

onRestart():当一个Activity再次启动之前将会调用该函数

FirstActivity.java

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

 public class FirstActivity extends Activity {

     private Button myButton;
     @Override
     protected void onCreate(Bundle savedInstanceState) {
         System.out.println("FirstAcvity ---> onCreate");
         super.onCreate(savedInstanceState);
         setContentView(R.layout.main);
         myButton = (Button)findViewById(R.id.myButton);
         myButton.setText("启动第二个Activity");
         myButton.setOnClickListener(new ButtonOnClickListener());
     }

     @Override
     protected void onDestroy() {
         System.out.println("FirstAcvity --->onDestory");
         super.onDestroy();
     }

     @Override
     protected void onPause() {
         System.out.println("FirstAcvity --->onPause");
         super.onPause();
     }

     @Override
     protected void onRestart() {
         System.out.println("FirstAcvity --->onRestart");
         super.onRestart();
     }

     @Override
     protected void onResume() {
         System.out.println("FirstAcvity --->onResume");
         super.onResume();
     }

     @Override
     protected void onStart() {
         System.out.println("FirstAcvity --->onStart");
         super.onStart();
     }

     @Override
     protected void onStop() {
         System.out.println("FirstAcvity --->onStop");
         super.onStop();
     }

     class ButtonOnClickListener implements OnClickListener{
         public void onClick(View v) {
             Intent intent = new Intent();
             intent.setClass(FirstActivity.this,SecondActivity.class);
             FirstActivity.this.startActivity(intent);
         }

     }
 }

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

SecondActivity.java

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

 public class SecondActivity extends Activity {
     @Override
     protected void onCreate(Bundle savedInstanceState) {
         System.out.println("SecondActivity--->onCreate");
         super.onCreate(savedInstanceState);
         setContentView(R.layout.second);
     }

     @Override
     protected void onDestroy() {
         System.out.println("SecondActivity--->onDestory");
         super.onDestroy();
     }

     @Override
     protected void onPause() {
         System.out.println("SecondActivity--->onPause");
         super.onPause();
     }

     @Override
     protected void onRestart() {
         System.out.println("SecondActivity--->onRestart");
         super.onRestart();
     }

     @Override
     protected void onResume() {
         System.out.println("SecondActivity--->onResume");
         super.onResume();
     }

     @Override
     protected void onStart() {
         System.out.println("SecondActivity--->onStart");
         super.onStart();
     }

     @Override
     protected void onStop() {
         System.out.println("SecondActivity--->onStop");
         super.onStop();
     }

 }

second.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:id="@+id/textview"
     android:layout_width="fill_parent"
     android:layout_height="wrap_content"
     android:text="huangjianfeng"
     />

 </LinearLayout>

AndroidManifest.xml

 <?xml version="1.0" encoding="utf-8"?>
 <manifest xmlns:android="http://schemas.android.com/apk/res/android"
     package="com.mars.activity04"
     android:versionCode="1"
     android:versionName="1.0" >

     <uses-sdk
         android:minSdkVersion="4"
         android:targetSdkVersion="18" />

     <application
         android:allowBackup="true"
         android:icon="@drawable/ic_launcher"
         android:label="@string/app_name"
         android:theme="@style/AppTheme" >
         <activity
             android:name="com.mars.activity04.FirstActivity"
             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=".SecondActivity" android:label="@string/second"/>
     </application>

 </manifest>

string.xml

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

    <string name="app_name">Activity04</string>
    <string name="action_settings">Settings</string>
    <string name="hello_world">Hello world!</string>
    <string name="second">第二个Activity</string>
</resources>

当启动应用程序时，启动了程序的第一个Activity，调用该Activity的onCreate(),onStart(),onResume()等方法

当启动应用程序的第二个Activity时,调用第一个Activity的onPause()和调用第二个Activity的onCreate(),onStart(),onResume()等方法，然后又调用第一个Activity的onStop()方法

当点击后退按钮回到第一个Activity的时候，调用第二个Activity的onPause()方法和调用第一个Activity的onRestart(),onStart(),onResume()等方法，然后调用第二个Activity的onStop()方法和onDestory()方法