问题描述

我在尝试在对话框中创建 Spinner 时遇到 NullPointerException，并且似乎无法调试它，因为代码看起来很可靠.想知道其他人是否有任何想法.非常感谢任何帮助.

I'm getting a NullPointerException while attempting to create a Spinner within a dialog and can't seem to debug it because the code looks solid. Wonder if anyone else has any idea. Any help is greatly appreciated.

    protected Dialog onCreateDialog(int id)
    {
        Dialog dialog;
        switch(id) {
        case DIALOG_SEND_PM:
            Spinner spinner = (Spinner)findViewById(R.id.pm_server);
            ArrayAdapter<CharSequence> adapter = ArrayAdapter.createFromResource(this, R.array.server_array, android.R.layout.simple_spinner_item);
            adapter.setDropDownViewResource(android.R.layout.simple_spinner_dropdown_item);
            spinner.setAdapter(adapter);
            spinner.setOnItemSelectedListener(new MyOnItemSelectedListener());

            dialog = new Dialog(PM.this);
            dialog.setContentView(R.layout.send_pm_dialog);
            dialog.setTitle(R.string.send_pm);
            pmMessage = (EditText) dialog.findViewById(R.id.send_pm_box);
            Button sendPm = (Button) dialog.findViewById(R.id.send_pm_button);
            sendPm.setOnClickListener(PM.this);
            break;
        default:
            dialog = null;
   }

我在 adapter.setDropDownViewResource(android.R.layout.simple_spinner_dropdown_item);我将上下文更改为 MyClass.this 并将异常移至下一行，这让我感到困惑.我想知道它是否是具有空值的适配器，但我在不在对话框中时以与以前相同的方式调用所有内容.

I get the exception at adapter.setDropDownViewResource(android.R.layout.simple_spinner_dropdown_item); I changed the context to MyClass.this and the exception moved down to the next line, which confuses me. I'm wondering if it is the adapter having a null value but I call everything the same way I have before while not in a dialog.

相关的 XML 数据:

Relevant XML data:

<LinearLayout>
    <TextView/>

    <LinearLayout>

       <TextView/>
      <EditText/>
      <TextView/>
      <Spinner
        android:id="@+id/pm_server"
        android:layout_height="fill_parent"
        android:layout_width="wrap_content"
        android:background="@drawable/yblueborder"
        android:textColor="#ABABAB"/>
    </LinearLayout>

    <Button/>
</LinearLayout>

编辑了其余的数据，以免占用太多空间.

Edited out the rest of the data so it wouldn't take up too much space.

推荐答案

我已经设法解决了这个问题.这是非常微妙的，我很确定我很幸运.这是工作代码:

I have managed to fix the issue. It was very subtle and I'm pretty sure I got lucky. Here's the working code:

protected Dialog onCreateDialog(int id)
    {
        Dialog dialog;
        switch(id) {
        case DIALOG_SEND_PM:
            dialog = new Dialog(PM.this);
            dialog.setContentView(R.layout.send_pm_dialog);
            dialog.setTitle(R.string.send_pm);
            pmMessage = (EditText) dialog.findViewById(R.id.send_pm_box);
            Button sendPm = (Button) dialog.findViewById(R.id.send_pm_button);
            sendPm.setOnClickListener(PM.this);

            Spinner spinner = (Spinner)dialog.findViewById(R.id.pm_server);
            ArrayAdapter<CharSequence> adapter = ArrayAdapter.createFromResource(this, R.array.server_array, android.R.layout.simple_spinner_item);
            adapter.setDropDownViewResource(android.R.layout.simple_spinner_dropdown_item);
            spinner.setAdapter(adapter);
            spinner.setOnItemSelectedListener(new MyOnItemSelectedListener());
            break;
        default:
            dialog = null;
        }
        return dialog;
    }

我移动了一些代码，以便在微调器之前初始化对话框，但这不是问题.我添加了对话框.在 Spinner spinner = (Spinner)dialog.findViewById(R.id.pm_server);这就是诀窍.希望这对其他人有帮助.

I moved some of the code around so that the dialog was initialized before the spinner, but that was not the issue. I added dialog. in Spinner spinner = (Spinner)dialog.findViewById(R.id.pm_server); and that did the trick. Hope this helps others.

这篇关于在自定义对话框中设置微调器的文章就介绍到这了，希望我们推荐的答案对大家有所帮助，也希望大家多多支持跟版网！