调试如下Android代码，弹出窗口
public class Offer_Popup extends Activity {
public void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.offer_popup);
//newly added code, the window popup
LayoutInflater inflater = (LayoutInflater)
this.getSystemService(Context.LAYOUT_INFLATER_SERVICE);
PopupWindow pw = new PopupWindow(
inflater.inflate(R.layout.popup_example, null, false),
100,
100,
true);
pw.showAtLocation(this.findViewById(R.id.relativeLayout_popup), Gravity.CENTER, 0, 0);}
/////////////////////
popup_example.xml
<?xml version="1.0" encoding="utf-8"?>
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
android:orientation="vertical"
android:padding="10dip"
android:layout_width="fill_parent"
android:layout_height="wrap_content"
>
<TextView
android:layout_width="fill_parent"
android:layout_height="wrap_content"
android:layout_marginTop="10dip"
android:text="Test Pop-Up"
/>
</LinearLayout>
DDMS 显示最后一行 showAtLocation 是错误。
它说无法添加窗口--令牌 null 无效。 android.view.WindowManagerBadToken。 在添加弹出窗口之前，程序运行良好。但是弹出代码后就崩溃了。它所说的坏标记是什么？
public class Offer_Popup extends Activity {
public void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.offer_popup);
//newly added code, the window popup
LayoutInflater inflater = (LayoutInflater)
this.getSystemService(Context.LAYOUT_INFLATER_SERVICE);
PopupWindow pw = new PopupWindow(
inflater.inflate(R.layout.popup_example, null, false),
100,
100,
true);
pw.showAtLocation(this.findViewById(R.id.relativeLayout_popup), Gravity.CENTER, 0, 0);}
/////////////////////
popup_example.xml
<?xml version="1.0" encoding="utf-8"?>
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
android:orientation="vertical"
android:padding="10dip"
android:layout_width="fill_parent"
android:layout_height="wrap_content"
>
<TextView
android:layout_width="fill_parent"
android:layout_height="wrap_content"
android:layout_marginTop="10dip"
android:text="Test Pop-Up"
/>
</LinearLayout>
DDMS shows the last line showAtLocation is the error.
It says Unable to add window--token null is invalid. android.view.WindowManagerBadToken.
Before adding the popup, the program runs fine. But after the popup code, it crashed. what's the bad token it's talking about?
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评论（2）
弹出窗口需要一个初始窗口才能弹出。人们可能会认为 Activity 会自动拥有一个 Window，但事实并非如此。给定的 Activity 在
onAttachedToWindow()之前没有活动窗口。此时，您可以将 PopupWindow 添加到 Window 中，因为存在 Window。如果您将代码移至 onAttachedToWindow()，它应该按预期工作，或者至少会给您一个完全不同的错误。
希望这有帮助，
模糊逻辑
A Popup Window requires an initial Window to be able to pop up from. One would think that an Activity automatically has a Window, but this is not the case right from the start. A given Activity does not have an active Window until
onAttachedToWindow(). At this time, you may add the PopupWindow to the Window becaue there is a Window present.If you move the code to the onAttachedToWindow(), it should work as intended or at least give you a different error entirely.
Hope this helps,
FuzzicalLogic
您确定布局文件中存在“popup_example”并且定义正确吗？
请仔细检查该文件。并在“膨胀” pw 后仔细检查它的值。
Are you sure "popup_example" exists, and is defined correctly, in your layout file?
Please double-check the file. And double-check the value of pw after you "inflate" it.