Aplication简单使用示例

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1.AndroidManifast.xml

<?xml version="1.0" encoding="utf-8"?><manifest xmlns:android="http://schemas.android.com/apk/res/android"    package="com.example.tt"    android:versionCode="1"    android:versionName="1.0" >    <uses-sdk        android:minSdkVersion="8"        android:targetSdkVersion="21" />    <application        android:name=".ASD"        android:allowBackup="true"        android:icon="@drawable/ic_launcher"        android:label="@string/app_name"        android:theme="@style/AppTheme" >        <activity            android:name=".MainActivity"            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=".MainActivity2"            android:label="@string/app_name" >            </activity>    </application></manifest>

2.layout几乎未修改（textView加了个id）

3.java

package com.example.tt;import android.app.Activity;import android.app.Application;import android.os.Bundle;import android.view.Menu;import android.view.MenuItem;public class ASD extends Application {int i ;@Overridepublic void onCreate() { //必须要复写，在所以的Activity创建前创建// TODO Auto-generated method stubsuper.onCreate();i =  10;}}

package com.example.tt;import android.app.Activity;import android.content.Intent;import android.os.Bundle;import android.view.Menu;import android.view.MenuItem;import android.view.View;import android.view.View.OnClickListener;import android.widget.TextView;public class MainActivity extends Activity {@Overrideprotected void onCreate(Bundle savedInstanceState) {super.onCreate(savedInstanceState);setContentView(R.layout.activity_main);//这里要重点注意（application在整个程序中都使用这种获取，以保证是单例模式，优化性能）ASD asd = (ASD) getApplication();TextView textView = (TextView) findViewById(R.id.tv);textView.setText(""+asd.i);asd.i = 12333;textView.setOnClickListener(new OnClickListener() {@Overridepublic void onClick(View v) {// TODO Auto-generated method stubIntent intent = new Intent(MainActivity.this,MainActivity2.class);startActivity(intent);}});}}

package com.example.tt;import android.app.Activity;import android.os.Bundle;import android.view.Menu;import android.view.MenuItem;import android.widget.TextView;public class MainActivity2 extends Activity {@Overrideprotected void onCreate(Bundle savedInstanceState) {super.onCreate(savedInstanceState);setContentView(R.layout.activity_main);ASD asd = (ASD) getApplication();TextView textView = (TextView) findViewById(R.id.tv);textView.setText(""+asd.i);}}

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