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グリッドレイアウトを作成していて、アラートダイアログに配置したいのですが、を使用してアラートダイアログを表示しようとするとshow()、アプリケーションに例外が表示されます。

コードは次のとおりです。

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();
      }

}

これは例外です：

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

どうすればこの問題を解決できますか？

4

3 に答える 3

7

アプリケーションコンテキストの代わりに現在のアクティビティコンテキストを次のように使用します

Context mContext = GridViewActivity.this;

それ以外の

Context mContext = getApplicationContext();
于 2012-07-21T09:49:18.983 に答える
3

この行を変更 

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

に 

AlertDialog.Builder builder = new AlertDialog.Builder(GridViewActivity.this);
于 2012-07-21T09:52:55.293 に答える
2

アプリケーションのコンテキストを使用するcontextのではなく、アクティビティをgetApplicationContext()使用するActivity_Name.this。

于 2012-07-21T09:49:06.157 に答える