在activity中使用menu

一：在res中新建一个menu的文件夹，然后在文件夹下面建一个main.xml文件，xml的代码如下

<?xml version="1.0" encoding="utf-8"?>
<menu xmlns:android="http://schemas.android.com/apk/res/android" >
    <item 
        android:id="@+id/add_item"
        android:title="Add"/>
    <item 
        android:id="@+id/remove_item"
        android:title="Remove"/>

二：在,MainActivity.java重写onCreateOptionsMenu()方法，在MainActivty.java中重写onOptionsItemSelected()方法，代码如下

package menudemo.zhangmeng.com.menudemo;

import android.support.v7.app.AppCompatActivity;
import android.os.Bundle;
import android.view.Menu;
import android.view.MenuItem;
import android.widget.Toast;

public class MainActivity extends AppCompatActivity {

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);
    }

    @Override
    public boolean onCreateOptionsMenu(Menu menu) {
        getMenuInflater().inflate(R.menu.main,menu);
        return true;
    }

    @Override
    public boolean onOptionsItemSelected(MenuItem item) {
        switch (item.getItemId()){
            case R.id.add_item:
                Toast.makeText(this, "you clicked add", Toast.LENGTH_SHORT).show();
                break;
            case R.id.remove_item:
                Toast.makeText(this, "you clicked remove", Toast.LENGTH_SHORT).show();
            default:
        }
        return true;

    }
}