popupMenu-----弹出菜单

import android.os.Bundle;
import android.app.Activity;
import android.graphics.Color;
import android.view.Menu;
import android.view.MenuItem;
import android.view.View;
import android.widget.PopupMenu;
import android.widget.PopupMenu.OnMenuItemClickListener;
import android.widget.TextView;

public class MainActivity extends Activity {

    private TextView textView;
    private float fontSize =15;
    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);
        
        textView = (TextView) findViewById(R.id.textView);
    }
    //弹出菜单是3.0开始出现的，所以api最低为11
    public void btnClick(View v)
    {
        //第二个参数是弹出菜单显示的参考位置,通常在参考视图的下边显示
        //创建一个弹出菜单对象
        PopupMenu  pop = new PopupMenu(this, v);
        
        //给菜单添加菜单项
        getMenuInflater().inflate(R.menu.main, pop.getMenu());
        
        //给菜单项添加事件监听
        pop.setOnMenuItemClickListener(new OnMenuItemClickListener() {
            
            @Override
            public boolean onMenuItemClick(MenuItem item) {
                switch(item.getItemId())
                {
                    case R.id.action_add:
                        fontSize+=5;
                        textView.setTextSize(fontSize);
                        break;
                    case R.id.action_sub:
                        fontSize-=5;
                        textView.setTextSize(fontSize);
                        break;
                    case R.id.action_background:
                        int red = (int)(Math.random()*256);
                        int green = (int)(Math.random()*256);
                        int blue = (int)(Math.random()*256);
                        textView.setBackgroundColor(Color.rgb(red, green, blue));
                        break;
                }
                return false;
            }
        });
        
        //显示菜单
        pop.show();
    }

}

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

     <item
        android:id="@+id/action_add"
        android:orderInCategory="100"
        android:showAsAction="never"
        android:title="放大字体"/>
    <item
        android:id="@+id/action_sub"
        android:orderInCategory="100"
        android:showAsAction="never"
        android:title="缩小字体"/>
    <item
        android:id="@+id/action_background"
        android:orderInCategory="100"
        android:showAsAction="never"
        android:title="改变背景颜色"/>

</menu>