android: ClassCastException:android.widget.spinner

Question

Here are the code snippet where I receive this error:

final PatchedSpinner spinner = (PatchedSpinner) findViewById(R.id.ActivitySpinner);

Here is the xml:

<Spinner
    android:id="@+id/ActivitySpinner"
    android:layout_width="wrap_content"
    android:layout_height="wrap_content"
    android:layout_alignParentLeft="true"
    android:layout_below="@+id/textView1"
    android:layout_marginTop="33dp" />

And also in the activity class I implement this:

public class PatchedSpinner extends Spinner {

    public PatchedSpinner(Context context, AttributeSet attrs, int defStyle) { 
        super(context, attrs, defStyle); 
    } 

    public PatchedSpinner(Context context) { 
        super(context); 
    } 

    public PatchedSpinner(Context context, AttributeSet attrs) { 
        super(context, attrs); 
    }

    @Override 
    public boolean performClick() {
        // this line removed, we do not want to delegate the click to the spinner.
        // boolean handled = super.performClick(); 

        Context context = getContext();

        final DropDownAdapter adapter = new DropDownAdapter(getAdapter());

        CharSequence mPrompt = getPrompt();

        AlertDialog.Builder builder = new AlertDialog.Builder(context); 
        if (mPrompt != null) { 
            builder.setTitle(mPrompt); 
        } 
        builder.setSingleChoiceItems(adapter, getSelectedItemPosition(), this).show();

        return true; 
    }
}

What am I doing wrong? I cast spinner to PatchedSpinner which extends Spinner...

The stacktrace:

05-05 23:56:11.149: E/AndroidRuntime(368): FATAL EXCEPTION: main
05-05 23:56:11.149: E/AndroidRuntime(368): java.lang.RuntimeException: Unable to start activity ComponentInfo{com.example.biohouse/com.example.biohouse.CalculateWatt}: android.view.InflateException: Binary XML file line #74: Error inflating class com.example.biohouse.PatchedSpinner
05-05 23:56:11.149: E/AndroidRuntime(368):  at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:2663)
05-05 23:56:11.149: E/AndroidRuntime(368):  at android.app.ActivityThread.handleLaunchActivity(ActivityThread.java:2679)
05-05 23:56:11.149: E/AndroidRuntime(368):  at android.app.ActivityThread.access$2300(ActivityThread.java:125)
05-05 23:56:11.149: E/AndroidRuntime(368):  at android.app.ActivityThread$H.handleMessage(ActivityThread.java:2033)
05-05 23:56:11.149: E/AndroidRuntime(368):  at android.os.Handler.dispatchMessage(Handler.java:99)
05-05 23:56:11.149: E/AndroidRuntime(368):  at android.os.Looper.loop(Looper.java:123)
05-05 23:56:11.149: E/AndroidRuntime(368):  at android.app.ActivityThread.main(ActivityThread.java:4627)
05-05 23:56:11.149: E/AndroidRuntime(368):  at java.lang.reflect.Method.invokeNative(Native Method)
05-05 23:56:11.149: E/AndroidRuntime(368):  at java.lang.reflect.Method.invoke(Method.java:521)
05-05 23:56:11.149: E/AndroidRuntime(368):  at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:868)
05-05 23:56:11.149: E/AndroidRuntime(368):  at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:626)
05-05 23:56:11.149: E/AndroidRuntime(368):  at dalvik.system.NativeStart.main(Native Method)
05-05 23:56:11.149: E/AndroidRuntime(368): Caused by: android.view.InflateException: Binary XML file line #74: Error inflating class com.example.biohouse.PatchedSpinner
05-05 23:56:11.149: E/AndroidRuntime(368):  at android.view.LayoutInflater.createViewFromTag(LayoutInflater.java:576)
05-05 23:56:11.149: E/AndroidRuntime(368):  at android.view.LayoutInflater.rInflate(LayoutInflater.java:618)
05-05 23:56:11.149: E/AndroidRuntime(368):  at android.view.LayoutInflater.inflate(LayoutInflater.java:407)
05-05 23:56:11.149: E/AndroidRuntime(368):  at android.view.LayoutInflater.inflate(LayoutInflater.java:320)
05-05 23:56:11.149: E/AndroidRuntime(368):  at android.view.LayoutInflater.inflate(LayoutInflater.java:276)
05-05 23:56:11.149: E/AndroidRuntime(368):  at android.support.v7.app.ActionBarActivityDelegateBase.setContentView(ActionBarActivityDelegateBase.java:128)
05-05 23:56:11.149: E/AndroidRuntime(368):  at android.support.v7.app.ActionBarActivity.setContentView(ActionBarActivity.java:76)
05-05 23:56:11.149: E/AndroidRuntime(368):  at com.example.biohouse.CalculateWatt.onCreate(CalculateWatt.java:41)
05-05 23:56:11.149: E/AndroidRuntime(368):  at android.app.Instrumentation.callActivityOnCreate(Instrumentation.java:1047)
05-05 23:56:11.149: E/AndroidRuntime(368):  at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:2627)
05-05 23:56:11.149: E/AndroidRuntime(368):  ... 11 more
05-05 23:56:11.149: E/AndroidRuntime(368): Caused by: java.lang.ClassNotFoundException: com.example.biohouse.PatchedSpinner in loader dalvik.system.PathClassLoader[/data/app/com.example.biohouse-1.apk]
05-05 23:56:11.149: E/AndroidRuntime(368):  at dalvik.system.PathClassLoader.findClass(PathClassLoader.java:243)
05-05 23:56:11.149: E/AndroidRuntime(368):  at java.lang.ClassLoader.loadClass(ClassLoader.java:573)
05-05 23:56:11.149: E/AndroidRuntime(368):  at java.lang.ClassLoader.loadClass(ClassLoader.java:532)
05-05 23:56:11.149: E/AndroidRuntime(368):  at android.view.LayoutInflater.createView(LayoutInflater.java:466)
05-05 23:56:11.149: E/AndroidRuntime(368):  at android.view.LayoutInflater.createViewFromTag(LayoutInflater.java:565)
05-05 23:56:11.149: E/AndroidRuntime(368):  ... 20 more

Answer 1

I think you need to call the related Class name as com.package.name.CustomWidget instead of the default widget Spinner in your view as follows:

<com.package.name.PatchedSpinner
    android:id="@+id/ActivitySpinner"
    android:layout_width="wrap_content"
    android:layout_height="wrap_content"
    android:layout_alignParentLeft="true"
    android:layout_below="@+id/textView1"
    android:layout_marginTop="33dp" />  

If this is not mentioned, the activity tries to find the default android.widget.Spinner whereas you declared this with PatchedSpinner. It might be the cause of the ClassCastException.

Also, make sure the custom class has the right constructors as:

public class PatchedSpinner extends Spinner {
    public PatchedSpinner(Context context) {
        super(context);
    }
    public PatchedSpinner(Context context, AttributeSet attrs) {
        super(context, attrs);
    }
    public PatchedSpinner(Context context, AttributeSet attrs, int defStyle) {
        super(context, attrs, defStyle);
    }
}