Android中在onCreate()時彈出popwindow，很多人都有過類似的需求吧，但是直接在onCreate()中調用popwindow的showAtLocation()方法是會報異常的，原因是此時activity還沒有初始化完畢，網上也有一些解決方法，但一般都是通過延時一小段時間再彈出實現的，代碼不夠健壯。其實可以通過不斷的檢測當前activity的狀態，一旦初始化完畢立即調用popwindow的showAtLocation()方法顯示。詳細代碼如下：

[java] view plaincopy

/************************************************************************?

?*?

?*?該類用來在初始化的時候彈出一個popwindow，用到的而已文件如下，特別要注意的是其中的??

?*?android:minHeight="1dp"?和android:minWidth="1dp"屬性。初始化時彈出popwindow的關鍵是?

?*?要等待整個activity初始化完畢后再調用showAtLocation()方法，否則會出異常。?

?*?實現方式就是不停的檢測acitvity是否初始化完畢，一旦完畢就調用?

?*?showAtLocation()?方法顯示popwindow。?

?*?

?*?以下為布局文件：?

?*??<?xml?version="1.0"?encoding="utf-8"?>?

?*??<LinearLayout?xmlns:android="http://schemas.android.com/apk/res/android"?

?*??????android:id="@+id/main"?

?*??????android:layout_width="fill_parent"?

?*??????android:layout_height="fill_parent"?

?*??????android:minHeight="1dp"?

?*??????android:minWidth="1dp"?

?*??????android:orientation="vertical"?>?

?*??</LinearLayout>?

?*?

?*?作者：石興?

?*?完成時間：2012/3/10?

?*?版本?：1.0?

?*?

?************************************************************************/??

??

package?cn.sd.sx.initpopw;??

??

import?android.app.Activity;??

import?android.graphics.Color;??

import?android.os.Bundle;??

import?android.os.Handler;??

import?android.view.Gravity;??

import?android.view.View;??

import?android.view.ViewGroup.LayoutParams;??

import?android.widget.LinearLayout;??

import?android.widget.PopupWindow;??

import?android.widget.TextView;??

import?cn.sd.sx.popw.R;??

??

public?class?PopWActivity?extends?Activity?{??

??????

????private?PopupWindow?mPopupWindow;??

????private?Handler?mHandler;??

????//?檢測時間間隔??

????private?int?detchTime?=?5;??

??????

????@Override??

????public?void?onCreate(Bundle?savedInstanceState)?{??

????????super.onCreate(savedInstanceState);??

????????setContentView(R.layout.main);??

????????mHandler?=?new?Handler();??

????????//?顯示popWindow??

????????showPopWindow();??

????}??

??

????private?void?showPopWindow()??

????{??

????????LinearLayout?view?=?new?LinearLayout(this);??

????????LayoutParams?params?=?new?LayoutParams(LayoutParams.FILL_PARENT,??

????????????????LayoutParams.FILL_PARENT);??

????????TextView?txt1?=?new?TextView(this);??

????????txt1.setLayoutParams(params);??

????????txt1.setGravity(Gravity.CENTER);??

????????txt1.setText("txt1");??

????????txt1.setBackgroundColor(Color.RED);??

????????view.addView(txt1);??

????????mPopupWindow?=?new?PopupWindow(view,?300,300);??

????????mPopupWindow.setOutsideTouchable(true);??

??????????

????????/*****************以下代碼用來循環檢測activity是否初始化完畢***************/??

????????Runnable?showPopWindowRunnable?=?new?Runnable()?{??

??????????????

????????????@Override??

????????????public?void?run()?{??

????????????????//?得到activity中的根元素??

????????????????View?view?=?findViewById(R.id.main);??

????????????????//?如何根元素的width和height大于0說明activity已經初始化完畢??

????????????????if(?view?!=?null?&&?view.getWidth()?>?0?&&?view.getHeight()?>?0)?{??

????????????????????//?顯示popwindow??

????????????????????mPopupWindow.showAtLocation(PopWActivity.this.findViewById(R.id.main),??

????????????????????????????Gravity.CENTER,?0,?0);??

????????????????????//?停止檢測??

????????????????????mHandler.removeCallbacks(this);??

????????????????}?else?{??

????????????????????//?如果activity沒有初始化完畢則等待5毫秒再次檢測??

????????????????????mHandler.postDelayed(this,?detchTime);??

????????????????}??

????????????}??

????????};??

????????//?開始檢測??

????????mHandler.post(showPopWindowRunnable);??

??????/******************以上代碼用來循環檢測activity是否初始化完畢*************/??

????}??

}?

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