Android笔记(2)---第一个 Android应用

1. 创建Android应用，目录结构如下图：
   
    
   
    MainActivity.java

   package com.example.helloworld;
   
   import android.app.Activity;
   import android.os.Bundle;
   import android.view.Menu;
   
   public class MainActivity extends Activity {
   
       @Override
       protected void onCreate(Bundle savedInstanceState) {
           super.onCreate(savedInstanceState);
           setContentView(R.layout.activity_main);
       }
   
   
       @Override
       public boolean onCreateOptionsMenu(Menu menu) {
           // Inflate the menu; this adds items to the action bar if it is present.
           getMenuInflater().inflate(R.menu.main, menu);
           return true;
       }
   
   }
   

     AndroidManifest.xml

   <?xml version="1.0" encoding="utf-8"?>
   <manifest xmlns:android="http://schemas.android.com/apk/res/android"
       package="com.example.helloworld"
       android:versionCode="1"
       android:versionName="1.0" >
   
       <uses-sdk
           android:minSdkVersion="12"
           android:targetSdkVersion="12" />
   
       <application
           android:allowBackup="true"
           android:icon="@drawable/ic_launcher"
           android:label="@string/app_name"
           android:theme="@style/AppTheme" >
           <activity
               android:name="com.example.helloworld.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>
       </application>
   
   </manifest>

    activity_main.xml

   <RelativeLayout xmlns:android="http://schemas.android.com/apk/res/android"
       xmlns:tools="http://schemas.android.com/tools"
       android:layout_width="match_parent"
       android:layout_height="match_parent"
       android:paddingBottom="@dimen/activity_vertical_margin"
       android:paddingLeft="@dimen/activity_horizontal_margin"
       android:paddingRight="@dimen/activity_horizontal_margin"
       android:paddingTop="@dimen/activity_vertical_margin"
       tools:context=".MainActivity" >
   
       <TextView
           android:layout_width="wrap_content"
           android:layout_height="wrap_content"
           android:text="@string/hello_world" />
   
   </RelativeLayout>

    
发布到模拟器上的效果图   

 发布到MX2上的截图