Question

最近我按照了如何创建警告对话框的教程，当我点击删除按钮时，它应该在删除之前显示警告但是它会崩溃。有人能告诉我我的错误在哪里吗？

以下是我的代码：

// Delete button click event
    btnDeleteEvent.setOnClickListener(new View.OnClickListener() {

        public void onClick(View arg0) {
            // alerting user before deleting event
            AlertDialog.Builder alertDialogBuilder = new AlertDialog.Builder(
                    getApplicationContext());
            // set title
            alertDialogBuilder.setTitle("Warning!");
            // set dialog message
            alertDialogBuilder
                    .setMessage("Are you sure to delete event?")
                    .setCancelable(false)
                    .setPositiveButton("Yes",
                            new DialogInterface.OnClickListener() {
                                public void onClick(DialogInterface dialog,
                                        int id) {
                                    // if yes, deleting event in background
                                    // thread
                                    new DeleteEvent().execute();
                                }
                            })
                    .setNegativeButton("No",
                            new DialogInterface.OnClickListener() {
                                public void onClick(DialogInterface dialog,
                                        int id) {
                                    // if this button is clicked, just close
                                    // the dialog box and do nothing
                                    dialog.cancel();
                                }
                            });

            // create alert dialog
            AlertDialog alertDialog = alertDialogBuilder.create();

            // show it
            alertDialog.show();
        }
    });

这是我的logcat：

08-18 02:02:45.804: E/AndroidRuntime(1288): FATAL EXCEPTION: main
08-18 02:02:45.804: E/AndroidRuntime(1288): android.view.WindowManager$BadTokenException: Unable to add window -- token null is not for an application
08-18 02:02:45.804: E/AndroidRuntime(1288):     at android.view.ViewRoot.setView(ViewRoot.java:509)
08-18 02:02:45.804: E/AndroidRuntime(1288):     at android.view.WindowManagerImpl.addView(WindowManagerImpl.java:177)
08-18 02:02:45.804: E/AndroidRuntime(1288):     at android.view.WindowManagerImpl.addView(WindowManagerImpl.java:91)
08-18 02:02:45.804: E/AndroidRuntime(1288):     at android.app.Dialog.show(Dialog.java:241)
08-18 02:02:45.804: E/AndroidRuntime(1288):     at com.stts.sparetimetradingsystem.employer.EditEventActivity$5.onClick(EditEventActivity.java:270)
08-18 02:02:45.804: E/AndroidRuntime(1288):     at android.view.View.performClick(View.java:2408)
08-18 02:02:45.804: E/AndroidRuntime(1288):     at android.view.View$PerformClick.run(View.java:8816)
08-18 02:02:45.804: E/AndroidRuntime(1288):     at android.os.Handler.handleCallback(Handler.java:587)
08-18 02:02:45.804: E/AndroidRuntime(1288):     at android.os.Handler.dispatchMessage(Handler.java:92)
08-18 02:02:45.804: E/AndroidRuntime(1288):     at android.os.Looper.loop(Looper.java:123)
08-18 02:02:45.804: E/AndroidRuntime(1288):     at android.app.ActivityThread.main(ActivityThread.java:4627)
08-18 02:02:45.804: E/AndroidRuntime(1288):     at java.lang.reflect.Method.invokeNative(Native Method)
08-18 02:02:45.804: E/AndroidRuntime(1288):     at java.lang.reflect.Method.invoke(Method.java:521)
08-18 02:02:45.804: E/AndroidRuntime(1288):     at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:868)
08-18 02:02:45.804: E/AndroidRuntime(1288):     at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:626)
08-18 02:02:45.804: E/AndroidRuntime(1288):     at dalvik.system.NativeStart.main(Native Method)

Answer 1

尝试使用Activity的上下文而不是应用程序上下文

Answer 2

使用dialog.dismiss（）甚至将getApplication上下文更改为YourActivity.this

您可以参考http://codinglookseasy.blogspot.in/2012/07/alert-box-code.html

Answer 3

根据this related question，您应该在构造函数中使用this而不是getApplicationContext()。

public void onClick(View arg0) {
    // alerting user before deleting event
    AlertDialog.Builder alertDialogBuilder = new AlertDialog.Builder(this);

为什么我的警报对话框崩溃了

3 个答案: