Using onClick attribute in layout xml causes a NoSuchMethodException in Android dialogs

Question

I have created a custom dialog and a layout xml:

Answer 1

A dialog is always created and displayed as part of an Activity. According to Android References:

If you decide to create a dialog outside of the onCreateDialog() method, 
it will not be attached to an Activity. You can, however, 
attach it to an Activity with setOwnerActivity(Activity).

Also, are you passing the object returned by getApplicationContext(); to the constructor of TestDialog?

Answer 2

Following on from Jett Hsieh's post, I've implemented my dialogs slightly differently using showDialog and dismissDialog, but the fundamentals of getting the android:onClick working have been the same, my example code is below for future reference.

public class ExampleActivity extends Activity { 
    static final int DIALOG_DISCLAIMER = 0;

    @Override
    public void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.main);

        showDialog(DIALOG_DISCLAIMER);
    }

    protected Dialog onCreateDialog(int id)
    {
        Dialog dialog;
        switch(id)
        {
            case DIALOG_DISCLAIMER:
                dialog = new Dialog(this);
                dialog.setContentView(R.layout.main_disclaimer);

                LinearLayout ll = (LinearLayout) LayoutInflater.from(this).inflate(R.layout.main_disclaimer, null);
                dialog.setContentView(ll);

                break;
            default:
                dialog = null;
        }       
        return dialog;
    }

    public void onClick(View v)
    {
        switch(v.getId())
        {
            case R.id.maindisclaimer_button_accept:
                dismissDialog(DIALOG_DISCLAIMER);
                break;
        }
    }
}

And the layout file:

<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
              android:layout_width="fill_parent" 
              android:layout_height="fill_parent" 
              android:id="@+id/linearLayout1" 
              android:padding="10dp" 
              android:orientation="vertical"
              android:background="@drawable/roundedcorners">
    <Button
            android:id="@+id/maindisclaimer_button_accept"
            android:layout_width="wrap_content"
            android:layout_height="wrap_content"
            android:layout_gravity="center"
            android:text="@string/string_accept"
            android:onClick="onClick" >
        </Button>
</LinearLayout>

Answer 3

Try to define that method (dialogClicked) in the activity and not in the dialog.

It might use reflection so if you use different activities just write that method in each activity that might show that dialog

Answer 4

I've found the following code in the View.java source:

public void onClick(View v) {
                            if (mHandler == null) {
                                try {
                                    mHandler = getContext().getClass().getMethod(handlerName,
                                            View.class);
    ...

-> The views uses its context to resolve the onclick handler method.

Noew the following code from Dialog.java source:

public Dialog(Context context, int theme) {
    mContext = new ContextThemeWrapper(context, theme == 0 ? com.android.internal.R.style.Theme_Dialog : theme);
    ...

In the constructor of the dialog an instance of ContextThemeWrapper gets created and set as context. This instance is neither the custom dialog class, nor the calling activity, which can be the place for implementing the handler method. Therefore views are not able to find the onclick handler method.

But I have to use the onclick XML attribut. Any workarounds available?

Answer 5

I think the issue is one of scope. I'm not sure how'd you address this in xml, but essentially the dialogueClicked method in your layout xml doesn't know where to find the method you've defined in the dialog class.

The standard approach i've seen to bind buttons in custom layouts is as follows.

1. implement the OnClickListener class
2. Bind the buttons click event to the dialog class
3. Switch out the buttons in the onClick button based on id. You'd need to add an id to your button.

.

public class TestDialog extends Dialog implements android.view.View.OnClickListener
{
    protected void onCreate(final Bundle savedInstanceState)
    {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.dialog);
        ((Button)findViewById(R.id.dialog_btn_mybutton)).setOnClickListener(this);
    }



public void onClick(View view) 
{
    switch (view.getId())
    {
        case R.id.dialog_btn_mybutton:
            //do stuff
            // dismiss();
            // cancel etc.
        break;
    }
}

}

Hope that helps. Would still be interested in knowing if there was a solution to using xml onClick to bind to the method. Perhaps an additional argument in the setContentView? something r'other.

Answer 6

Define the method (dialogClicked) in Activity. And modify TestDialog like the following code:

public class TestDialog extends Dialog {
 Context mContext;
 public TestDialog(final Context context)
 {

  super(context);
  mContext=context;
 }

 @Override
 protected void onCreate(final Bundle savedInstanceState)
 {
  super.onCreate(savedInstanceState);
  LinearLayout ll=(LinearLayout) LayoutInflater.from(mContext).inflate(R.layout.dialog, null);
  setContentView(ll); 
 }
}

I think it works :)