Android学习笔记五

今天做一个关于Menu的案例，在案例中需要重写onCreateOptionsMenu和onCreateOptionsMenu函数，这里要注意的是onCreateOptionsMenu重写的只有一个参数的，还要注意要在string.xml中定义变量

这是ActivityMain.java的代码

package com.eoeAndroidMenu;

import android.app.Activity;
import android.os.Bundle;
import android.view.Menu;
import android.view.MenuItem;
import android.view.View;
import android.widget.Button;

public class ActivityMain extends Activity {
 
 public static final int ITEM0=Menu.FIRST;
 public static final int ITEM1=Menu.FIRST+1;
 
 Button button1=null;
 Button button2=null;
 
    /** Called when the activity is first created. */
    @Override
    public void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.main);
        button1=(Button)findViewById(R.id.button1);
        button2=(Button)findViewById(R.id.button2);
        button1.setVisibility(View.INVISIBLE);
        button2.setVisibility(View.INVISIBLE);
    }
   
    @Override
 public boolean onCreateOptionsMenu(Menu menu) {
  // TODO Auto-generated method stub
     super.onCreateOptionsMenu(menu);
  menu.add(0, ITEM0, 0, "显示button1");
  menu.add(0, ITEM1, 0, "显示button2");
  menu.findItem(ITEM1);
  return true;
 }
 @Override
 public boolean onOptionsItemSelected(MenuItem item) {
  // TODO Auto-generated method stub
  switch(item.getItemId()){
  case ITEM0:actionClickMenuItem1();break;
  case ITEM1:actionClickMenuItem2(); break;
  }
  return super.onOptionsItemSelected(item);
 }

 private void actionClickMenuItem1() {
  // TODO Auto-generated method stub
  setTitle("button1可见");
  button1.setVisibility(View.VISIBLE);
  button2.setVisibility(View.INVISIBLE);
 }
 private void actionClickMenuItem2() {
  // TODO Auto-generated method stub
  setTitle("button2可见");
  button1.setVisibility(View.INVISIBLE);
  button2.setVisibility(View.VISIBLE);
 }
}

这是main.xml的代码

<?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:layout_width="fill_parent"
    android:layout_height="wrap_content"
    android:text="@string/hello"
    />
<Button android:id="@+id/button1"
 android:layout_width="100px"
 android:layout_height="wrap_content" android:text="@string/button1"/>
<Button android:id="@+id/button2"
 android:layout_width="wrap_content"
 android:layout_height="wrap_content" android:text="@string/button2"/>
</LinearLayout>
这是string.xml

 <?xml version="1.0" encoding="utf-8"?>
<resources>
    <string name="hello">Hello World, ActivityMain!</string>
    <string name="app_name">MenuTest</string>
    <string name="button1">button1</string>
    <string name="button2">button2</string>
</resources>