Question

我正在制作网格布局，并希望将其置于警告对话框中，但当我尝试使用show()显示警告对话框时，应用程序会显示异常。

以下是代码：

public class GridViewActivity extends Activity {

    GridView gridView;
    Context context;

    static final String[] MOBILE_OS = new String[] { "timer", "about"};

    @Override
    public void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.main);

        gridView = (GridView) findViewById(R.id.gridView1);
        gridView.setAdapter(new ImageAdapter(this, MOBILE_OS));
        gridView.setOnItemClickListener(new OnItemClickListener() {
            public void onItemClick(AdapterView<?> parent, View v,
                    int position, long id) {
                //              Toast.makeText(
                //                      getApplicationContext(),
                //                      ((TextView) v.findViewById(R.id.grid_item_label))
                //                              .getText(), Toast.LENGTH_SHORT).show();
                if(position == 0){
                    Toast.makeText(GridViewActivity.this, "first icon is pressed", Toast.LENGTH_SHORT).show();
                }
                else if(position == 1){
                    Toast.makeText(GridViewActivity.this, "second icon is pressed", Toast.LENGTH_SHORT).show();
                }
            }});
        Dialog();
    }   
    private void Dialog(){
        AlertDialog alertDialog;
        Context mContext = getApplicationContext();
        AlertDialog.Builder builder = new AlertDialog.Builder(mContext);
        LayoutInflater inflater = (LayoutInflater) mContext.getSystemService(LAYOUT_INFLATER_SERVICE);
        View layout = inflater.inflate(R.layout.main,null);
        builder.setView(layout);
        alertDialog = builder.create();
        alertDialog.show();
      }

}

这是一个例外：

07-21 14:59:51.832: E/AndroidRuntime(1683): FATAL EXCEPTION: main
07-21 14:59:51.832: E/AndroidRuntime(1683): java.lang.RuntimeException: Unable to start activity ComponentInfo{com.velosys.main/com.velosys.main.GridViewActivity}: android.view.WindowManager$BadTokenException: Unable to add window -- token null is not for an application
07-21 14:59:51.832: E/AndroidRuntime(1683):     at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:1647)
07-21 14:59:51.832: E/AndroidRuntime(1683):     at android.app.ActivityThread.handleLaunchActivity(ActivityThread.java:1663)
07-21 14:59:51.832: E/AndroidRuntime(1683):     at android.app.ActivityThread.access$1500(ActivityThread.java:117)
07-21 14:59:51.832: E/AndroidRuntime(1683):     at android.app.ActivityThread$H.handleMessage(ActivityThread.java:931)
07-21 14:59:51.832: E/AndroidRuntime(1683):     at android.os.Handler.dispatchMessage(Handler.java:99)
07-21 14:59:51.832: E/AndroidRuntime(1683):     at android.os.Looper.loop(Looper.java:123)
07-21 14:59:51.832: E/AndroidRuntime(1683):     at android.app.ActivityThread.main(ActivityThread.java:3683)
07-21 14:59:51.832: E/AndroidRuntime(1683):     at java.lang.reflect.Method.invokeNative(Native Method)
07-21 14:59:51.832: E/AndroidRuntime(1683):     at java.lang.reflect.Method.invoke(Method.java:507)
07-21 14:59:51.832: E/AndroidRuntime(1683):     at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:839)
07-21 14:59:51.832: E/AndroidRuntime(1683):     at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:597)
07-21 14:59:51.832: E/AndroidRuntime(1683):     at dalvik.system.NativeStart.main(Native Method)
07-21 14:59:51.832: E/AndroidRuntime(1683): Caused by: android.view.WindowManager$BadTokenException: Unable to add window -- token null is not for an application
07-21 14:59:51.832: E/AndroidRuntime(1683):     at android.view.ViewRoot.setView(ViewRoot.java:531)
07-21 14:59:51.832: E/AndroidRuntime(1683):     at android.view.WindowManagerImpl.addView(WindowManagerImpl.java:177)
07-21 14:59:51.832: E/AndroidRuntime(1683):     at android.view.WindowManagerImpl.addView(WindowManagerImpl.java:91)
07-21 14:59:51.832: E/AndroidRuntime(1683):     at android.app.Dialog.show(Dialog.java:241)
07-21 14:59:51.832: E/AndroidRuntime(1683):     at com.velosys.main.GridViewActivity.Dialog(GridViewActivity.java:58)
07-21 14:59:51.832: E/AndroidRuntime(1683):     at com.velosys.main.GridViewActivity.onCreate(GridViewActivity.java:48)
07-21 14:59:51.832: E/AndroidRuntime(1683):     at android.app.Instrumentation.callActivityOnCreate(Instrumentation.java:1047)
07-21 14:59:51.832: E/AndroidRuntime(1683):     at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:1611)
07-21 14:59:51.832: E/AndroidRuntime(1683):     ... 11 more

我该如何解决这个问题？

Answer 1

使用当前活动上下文而不是应用程序上下文

Context mContext = GridViewActivity.this;

而不是

Context mContext = getApplicationContext();

Answer 2

更改此行

AlertDialog.Builder builder = new AlertDialog.Builder(mContext);

到

AlertDialog.Builder builder = new AlertDialog.Builder(GridViewActivity.this);

Answer 3

使用活动的context而不是使用应用程序的上下文作为getApplicationContext()，因此请使用Activity_Name.this。

alert.show（）无法在警报对话框中工作

3 个答案: