public class MainActivity extends Activity {    private PopupWindow pop;         @Override    protected void onCreate(Bundle savedInstanceState) {        super.onCreate(savedInstanceState);        setContentView(R.layout.test);                //将layout的xml布局文件实例化为View类对象        LayoutInflater inflater =LayoutInflater.from(this);                View view =inflater.inflate(R.layout.mypop, null);                //创建PopupWindow，参数为显示对象，宽，高        final PopupWindow pop =new PopupWindow(view, LayoutParams.WRAP_CONTENT, LayoutParams.WRAP_CONTENT);                //PopupWindow的设置        pop.setBackgroundDrawable(new BitmapDrawable());                //点击外边消失        pop.setOutsideTouchable(true);              //设置此参数获得焦点，否则无法点击         pop.setFocusable(true);                //设置文本监听事件        TextView text =(TextView) findViewById(R.id.topmenu);        text.setOnClickListener(new OnClickListener(){            @Override            //判断是否已经显示，点击时如显示则隐藏，隐藏则显示            public void onClick(View v) {                if(pop.isShowing()){                    pop.dismiss();                }else{                    pop.showAsDropDown(v);                }                            }                                        });