Android 菜单学习笔记

1.MainActivity.java

public class MainActivity extends Activity {
// 定义两个 id 作为两个菜单项的标识	public static final int ITEM0 = Menu.FIRST;	public static final int ITEM1 = Menu.FIRST + 1;
private Button button1;	private Button button2;
@Override	protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);		button1 = (Button) findViewById(R.id.button1);		button2 = (Button) findViewById(R.id.button2);		button1.setVisibility(View.INVISIBLE);		button2.setVisibility(View.INVISIBLE);		System.out.println("oncreate()");	}
/* 该方法标示显示菜单的方法 */	public boolean onCreateOptionsMenu(Menu menu) {		super.onCreateOptionsMenu(menu);		// 添加菜单		menu.add(0, ITEM0, 0, "显示 button1");		menu.add(0, ITEM1, 0, "显示 button2");		// return true 才会起作用		return true;	}
@Override	public boolean onOptionsItemSelected(MenuItem item) {		switch (item.getItemId()) {		case ITEM0:			System.out.println("menu1 的 id"+ item.getItemId());			actionClickMenultem1();			break;		case ITEM1:			System.out.println("menu2 的 id"+ item.getItemId());			actionClickMenultem2();			break;		}		return super.onOptionsItemSelected(item);	}
// 菜单项被选中的方法	public boolean onOptionsltemSelected(MenuItem item) {		System.out.println("----------OnOptionsItem");
return super.onOptionsItemSelected(item);	}
/* 点击第一个 menu 的执行动作 */	private void actionClickMenultem1() {		setTitle("button1 可见");		button1.setVisibility(View.VISIBLE);		button2.setVisibility(View.INVISIBLE);	}
private void actionClickMenultem2() {		setTitle("button2 可见");		button1.setVisibility(View.INVISIBLE);		button2.setVisibility(View.VISIBLE);	}}

2.activity_main.xml

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

<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"

android:layout_width="fill_parent"

android:layout_height="fill_parent"

android:orientation="vertical" >

<Button

android:id="@+id/button1"

android:layout_width="wrap_content"

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>