对话框中的微调器 - NullPointerException

我想用微调器显示自定义对话框。奇怪的是，当我尝试设置微调器的适配器时，我收到 NullPointerException...

Dialog dialog = new Dialog(this.getApplicationContext());
dialog.setContentView(R.layout.dialog_spinner);

ArrayAdapter<String> spinnerAdapter = new ArrayAdapter<String>(this, android.R.layout.simple_spinner_item, new String[] {"0","1","2"});

spin = (Spinner)dialog.findViewById(R.id.spinQ);
//What am I doing wrong here?
spin.setAdapter(spinnerAdapter);

dialog.setTitle("Questions");
dialog.show();

xml布局代码：

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

<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
android:orientation="vertical"
android:layout_height="fill_parent"
android:layout_width="fill_parent"
android:paddingLeft="10dip"
>

<Spinner 
android:id="@+id/spinQ" 
android:layout_width="fill_parent" 
android:layout_height="wrap_content"
/> 


</LinearLayout>

UPDATE:

        AlertDialog alertDialog;


        LayoutInflater inflater = (LayoutInflater) getApplicationContext().getSystemService(LAYOUT_INFLATER_SERVICE);
        View layout = inflater.inflate(R.layout.dialog_spinner,
                                       (ViewGroup) findViewById(R.id.root));

        ArrayAdapter<String> spinnerAdapter = new ArrayAdapter<String>(this,
              android.R.layout.simple_spinner_item, new String[] {"0","1","2"});
        spin = (Spinner) findViewById(R.id.spinQ);
        //I get the error in the following line:
        spin.setAdapter(spinnerAdapter);

        builder = new AlertDialog.Builder(mContext);
        builder.setView(layout);
        alertDialog = builder.create();
        alertDialog.show();

Your Spinner可能还没有充气。如果你想操纵视图，请自己充气，然后使用setContentView在充气的View。请参阅docs http://developer.android.com/guide/topics/ui/dialogs.html关于创建对话框。

Update:

在您的新代码中，更改：

spin = (Spinner) findViewById(R.id.spinQ);

to:

spin = (Spinner) layout.findViewById(R.id.spinQ);