Android learning: Use menu

Mainactivity. Java

Package COM. example. examples_04_13; import android. OS. bundle; import android. app. activity; import android. content. intent; import android. view. menu; import android. view. menuitem; public class mainactivity extends activity {@ overrideprotected void oncreate (bundle savedinstancestate) {super. oncreate (savedinstancestate); setcontentview (R. layout. activity_main) ;}@ overridepublic Boolean oncreateoptionsmenu (menu) {// inflate the menu; this adds items to the action bar if it is present. getmenuinflater (). inflate (R. menu. main, menu); Return true;}/* process menu events */Public Boolean onoptionsitemselected (menuitem item) {// todo auto-generated method stubint item_id = item. getitemid (); Switch (item_id) {case R. id. about: intent = new intent (); intent. setclass (mainactivity. this, activity2.class); startactivity (intent); mainactivity. this. finish (); break; case R. id. exit: mainactivity. this. finish (); default: break;} return Super. onoptionsitemselected (item );}}

Activity2.java

Package COM. example. examples_04_13; import android. app. activity; import android. content. intent; import android. OS. bundle; import android. view. menu; import android. view. menuitem; public class activity2 extends activity {@ overrideprotected void oncreate (bundle savedinstancestate) {// todo auto-generated method stubsuper. oncreate (savedinstancestate); setcontentview (R. layout. layout2);}/* Create menu */Public Boolean oncreateoptionsmenu (menu) {// Add content menu for menu. add (0, 0, 0, R. string. OK); menu. add (0, 1, 1, R. string. back); return Super. oncreateoptionsmenu (menu);}/* process menu events */Public Boolean onoptionsitemselected (menuitem item) {int item_id = item. getitemid (); Switch (item_id) {Case 0: activity2.this. finish (); break; Case 1: intent = new intent (); intent. setclass (activity2.this, mainactivity. class); startactivity (intent); activity2.this. finish (); break; default: break;} return Super. onoptionsitemselected (item );}}

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="MainActivity" /></RelativeLayout>

Layout2.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="wrap_content"    android:layout_height="wrap_content"    android:text="Activity2"/>    </LinearLayout>

Res/menu/Main. xml

<Menu xmlns: Android = "http://schemas.android.com/apk/res/android"> <item Android: Id = "@ + ID/about" Android: Title = "about"/> <item Android: id = "@ + ID/exit" Android: Title = "quit"/> </menu>

Androidmanifest. xml

<?xml version="1.0" encoding="utf-8"?><manifest xmlns:android="http://schemas.android.com/apk/res/android"    package="com.example.examples_04_13"    android:versionCode="1"    android:versionName="1.0" >    <uses-sdk        android:minSdkVersion="8"        android:targetSdkVersion="17" />    <application        android:allowBackup="true"        android:icon="@drawable/ic_launcher"        android:label="@string/app_name"        android:theme="@style/AppTheme" >        <activity            android:name="com.example.examples_04_13.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="com.example.examples_04_13.Activity2">                    </activity>    </application></manifest>