求指教,程序能运行,但是达不到效果~~

public class MainActivity extends Activity {
private WindowManager wm;
private LayoutParams params;
private boolean isAdded;
private Button btn_floatView;
private WindowManager windowManager;
private Display display;
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
createFloatView();
buttonClickListener listener = new buttonClickListener();
btn_floatView.setOnClickListener(listener);
this.finish();
}
这是mianActivityI

private void createFloatView() {
btn_floatView = new Button(getApplicationContext());
btn_floatView.setText("悬浮窗");
wm = (WindowManager) getApplicationContext().getSystemService(
Context.WINDOW_SERVICE);
params = new WindowManager.LayoutParams(); // 设置window type
params.type = WindowManager.LayoutParams.TYPE_SYSTEM_ALERT;
params.format = PixelFormat.RGBA_8888; // 设置图片格式，效果为背景透明
// 设置Window flag
params.flags = WindowManager.LayoutParams.FLAG_NOT_TOUCH_MODAL;
params.width = 100;
params.height = 100;
wm.addView(btn_floatView, params);
isAdded = true;
}
浮动窗口的创建I

截屏的代码就不上了,在非浮动窗口的Activity里面点击按钮截屏功能能够正常使用.就是那个listener类