How do I properly extend a layout class?

Question

I want to make a custom RelativeLayout, but I keep getting this error:

08-01 02:28:19.385: E/AndroidRuntime(9989): FATAL EXCEPTION: main
08-01 02:28:19.385: E/AndroidRuntime(9989): android.view.InflateException: Binary XML     file line #1: Error inflating class com.stevenschoen.putio.CheckableRelativeLayout
08-01 02:28:19.385: E/AndroidRuntime(9989):     at     android.view.LayoutInflater.createView(LayoutInflater.java:596)
08-01 02:28:19.385: E/AndroidRuntime(9989):     at     android.view.LayoutInflater.createViewFromTag(LayoutInflater.java:687)
08-01 02:28:19.385: E/AndroidRuntime(9989):     at     android.view.LayoutInflater.inflate(LayoutInflater.java:466)
08-01 02:28:19.385: E/AndroidRuntime(9989):     at     android.view.LayoutInflater.inflate(LayoutInflater.java:396)

...

08-01 02:28:19.385: E/AndroidRuntime(9989): Caused by: java.lang.NoSuchMethodException:     <init> [class android.content.Context, interface android.util.AttributeSet]
08-01 02:28:19.385: E/AndroidRuntime(9989):     at     java.lang.Class.getConstructorOrMethod(Class.java:460)
08-01 02:28:19.385: E/AndroidRuntime(9989):     at     java.lang.Class.getConstructor(Class.java:431)
08-01 02:28:19.385: E/AndroidRuntime(9989):     at     android.view.LayoutInflater.createView(LayoutInflater.java:561)

And here's my class:

public class CheckableRelativeLayout extends RelativeLayout implements
        Checkable {

    public CheckableRelativeLayout(Context context) {
        super(context);
        // TODO Auto-generated constructor stub
    }

    private boolean isChecked;
//  List<Checkable> checkableViews = new ArrayList<Checkable>();

    // @see android.widget.Checkable#isChecked()
    public boolean isChecked() {
        return isChecked;
    }

    // @see android.widget.Checkable#setChecked(boolean)
    public void setChecked(boolean isChecked) {
        this.isChecked = isChecked;
//      for (Checkable c : checkableViews) {
            // Pass the information to all the child Checkable widgets
//          c.setChecked(isChecked);
//      }
    }

    // @see android.widget.Checkable#toggle()
    public void toggle() {
        this.isChecked = !this.isChecked;
//      for (Checkable c : checkableViews) {
            // Pass the information to all the child Checkable widgets
//          c.toggle();
//      }
    }

    @Override
    protected void onFinishInflate() {
        super.onFinishInflate();

        final int childCount = this.getChildCount();
        for (int i = 0; i < childCount; ++i) {
            findCheckableChildren(this.getChildAt(i));
        }
    }

    /**
     * Add to our checkable list all the children of the view that implement the
     * interface Checkable
     */
    private void findCheckableChildren(View v) {
        if (v instanceof Checkable) {
//          this.checkableViews.add((Checkable) v);
        }

        if (v instanceof ViewGroup) {
            final ViewGroup vg = (ViewGroup) v;
            final int childCount = vg.getChildCount();
            for (int i = 0; i < childCount; ++i) {
                findCheckableChildren(vg.getChildAt(i));
            }
        }
    }
}

What am I doing wrong?

Answer 1

You implemented only one constructor. To be able use views in xml, you should implement 2 other constructors from View:

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

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

Answer 2

You forgot to override constructor, each layout can be created from code or from XML and for creation used different constructors, override another one