弹窗大小

private AlertDialog alertDialog2; //单选框

//在show方法后使用
WindowManager wm = (WindowManager) this.getSystemService(Context.WINDOW_SERVICE);
DisplayMetrics dm = new DisplayMetrics();
wm.getDefaultDisplay().getMetrics(dm);
int width = dm.widthPixels;         // 屏幕宽度（像素）
int height = dm.heightPixels;       // 屏幕高度（像素）
WindowManager.LayoutParams params = alertDialog2.getWindow().getAttributes();
params.width = (int) (0.65*width);

if (item.size() < 10) {
    params.height = WindowManager.LayoutParams.WRAP_CONTENT;
} else {
    params.height = (int) (0.6 * height);
}

alertDialog2.getWindow().setAttributes(params);