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android – onTouchListener warning: onTouch should call View#performClick when a click is detected

Posted by: admin March 11, 2020 Leave a comment

Questions:

I have created a onTouchListener. Unfortunately onTouch() method throws me a warning:

com/calculator/activitys/Calculator$1#onTouch should call View#performClick when a click is detected

What does it means? I have not found any information about this warn. Here is the full code:

LinearLayout llCalculatorContent = (LinearLayout) fragmentView.findViewById(R.id.calculator_content);

llCalculatorContent.setOnTouchListener(new View.OnTouchListener() {

    @Override
    public boolean onTouch(View v, MotionEvent event) {
        Tools.hideKeyboard(getActivity(), getView());
        getView().clearFocus();
        return false;
    }   
});
How to&Answers:

Here you go:

public boolean onTouch(View v, MotionEvent event) {
    switch (event.getAction()) {
    case MotionEvent.ACTION_DOWN:
        //some code....
        break;
    case MotionEvent.ACTION_UP:
        v.performClick();
        break;
    default:
        break;
    }
    return true;
}

Answer:

You can suppress the Lint

@SuppressLint("ClickableViewAccessibility")

You should call performClick() inside onTouchEvent().

@Override
public boolean onTouchEvent(MotionEvent event) {
    //A logic 

    performClick();
    return super.onTouchEvent(event);
}

or

findViewById(R.id.view1).setOnTouchListener(new View.OnTouchListener() {
    @Override
    public boolean onTouch(View v, MotionEvent event) {

        v.performClick();

        return v.onTouchEvent(event);
    }
});

OnTouch flow

Read more here

Answer:

In case you’re not using a Custom View which explicitly overrides onPerformClick , the warning won’t get removed by just following Secko’s answer.

In addition to his answer, for doing the same on classes like android.widget.Button or Button you need to make a simple custom view which extends the target view.

Example :

The Custom View Class:

public class UselessButton extends AppCompatButton {
    public UselessButton(Context context) {
        super(context);
    }

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

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

    @Override
    public boolean performClick() {
        return super.performClick();
    }
}

XML :

<stackoverflow.onEarth.UselessButton
    android:id="@+id/left"
    android:layout_width="60dp"
    android:layout_height="60dp"
    android:layout_marginStart="16dp"
    android:layout_marginTop="16dp"
    android:layout_marginEnd="8dp"
    android:layout_marginBottom="8dp"
    android:background="@drawable/left"
    app:layout_constraintBottom_toBottomOf="parent"
    app:layout_constraintEnd_toEndOf="parent"
    app:layout_constraintHorizontal_bias="0.16"
    app:layout_constraintStart_toStartOf="parent"
    app:layout_constraintTop_toTopOf="parent"
    app:layout_constraintBaseline_toBaselineOf="@+id/right"
    app:layout_constraintVertical_bias="0.5" />

Java :

    left.setOnTouchListener((v, event) -> {
        if (event.getAction() == MotionEvent.ACTION_DOWN) {
            enLeft = 1;
            enRight = 0;
            return true;
        } else if (event.getAction() == MotionEvent.ACTION_UP) {
            enLeft = 0;
            v.performClick();
            return false;
        } else {
            return false;
        }
    });

Current problems : Warning gets resolved by IDE, but can’t see this practically performing click action on a real Android Device.

EDIT: Fixed getting the click event : Use View.setPressed(boolean)

down.setOnTouchListener((v, event) -> {
    if (event.getAction() == MotionEvent.ACTION_DOWN) {
        enFront = 0;
        enBack = 1;
        left.setPressed(true);
        return true;
    } else if (event.getAction() == MotionEvent.ACTION_UP) {
        enBack = 0;
        v.performClick();
        v.setPressed(false);
        return false;
    } else {
        return false;
    }

Answer:

just call performClick method, like this:

@Override
public boolean onTouch(View v, MotionEvent event) {
    v.performClick();
    Tools.hideKeyboard(getActivity(), getView());
    getView().clearFocus();
    return false;
}   

Answer:

I had a similar issue with a MultiTouchListener and solved it implementing a GestureDetector and listening for a SingleTap (This does not remove the warning but starts to triggering onClick events on my view)

class TouchListener(context: Context) : MultiTouchListener() {

    private var tochedView: View? = null
    private var mGestureDetector = CustomGestureDetector()
    private var gestureDetector: GestureDetector = GestureDetector(context, mGestureDetector)

    @SuppressLint("ClickableViewAccessibility")
    override fun onTouch(view: View?, event: MotionEvent?): Boolean {
        val aux = super.onTouch(view, event)

        tochedView = view
        gestureDetector.onTouchEvent(event)

        return aux
    }

    private inner class CustomGestureDetector: GestureDetector.SimpleOnGestureListener() {

        override fun onSingleTapUp(e: MotionEvent?): Boolean {
            // this will be called even when a double tap is
            tochedView?.performClick()
            return super.onSingleTapUp(e)
        }

        override fun onSingleTapConfirmed(e: MotionEvent?): Boolean {
            // this will only be called after the detector is confident that the
            // user's first tap is not followed by a second tap leading to a double-tap gesture.
            tochedView?.performClick()
            return super.onSingleTapConfirmed(e)
        }

    }

}