android-将ToggleButton转换为子类

Question

I might be misunderstanding type casting, but here is my problem.

I've got an Android View with a ToggleButton:

<LinearLayout
    ... >
    <ToggleButton
        android:id="@+id/btnRec"
        android:layout_width="125dp"
        android:layout_height="wrap_content"
        android:textOff="Start TEST"
        android:textOn="Stop TEST" />
    ...
</LinearLayout>

Then in my activity I declare a ToggleButton variable:

private ToggleButton mRecordButton = null;

Now, I implement a subclass of ToggleButton, called RecordButton:

class RecordButton extends ToggleButton {

    OnCheckedChangeListener clicker = new OnCheckedChangeListener() {
        ...
    };

    public RecordButton(Context ctx) {
        super(ctx);
        setOnCheckedChangeListener(clicker);
    }
}

And finally in onCreate I find the button by its id:

mRecordButton = (RecordButton) findViewById(R.id.btnRec);

This throws a ClassCastException .

Why? How can I cast it to RecordButton (the subclass) from ToggleButton (the superclass)?

Answer 1

in your XML, replace the regular ToogleButton with the custom one..

<LinearLayout
... >
<package.class.RecordButton
    android:id="@+id/btnRec"
    android:layout_width="125dp"
    android:layout_height="wrap_content"
    android:textOff="Start TEST"
    android:textOn="Stop TEST" />
...

Answer 2

You can use your views in layout:

<LinearLayout
    ... >
    <com.project.RecordButton
        android:id="@+id/btnRec"
        android:layout_width="125dp"
        android:layout_height="wrap_content"
        android:textOff="Start TEST"
        android:textOn="Stop TEST" />
    ...
</LinearLayout>

Eclipse with android SDK can automatically determine your views: