androidx.constraintlayout.widget.ConstraintLayout$LayoutParams cannot be cast to android.widget.RelativeLayout$LayoutParams

Question

I'm new to Android Studio and I just want to drag a TextView around. However, when I try to get the LayoutParams for the RelativeLayout, I get a ClassCastException for a class I don't use (ContraintLayout).

    import androidx.appcompat.app.AppCompatActivity;

    import android.os.Bundle;
    import android.view.MotionEvent;
    import android.view.View;
    import android.widget.RelativeLayout;
    import android.widget.TextView;

    public class MainActivity extends AppCompatActivity {

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);

        TextView textView=findViewById(R.id.textView);
        textView.setOnTouchListener(onTouchListener());
    }

    private View.OnTouchListener onTouchListener(){
        return new View.OnTouchListener(){
            @Override
            public boolean onTouch(View view, MotionEvent event){
                final int x= (int)event.getRawX();
                final int y= (int)event.getRawY();
                RelativeLayout.LayoutParams params= (RelativeLayout.LayoutParams)view.getLayoutParams();//<--ERROR
                return true;
            }
        };
    }
}

here is the error message

E/InputEventReceiver: Exception dispatching input event.
E/MessageQueue-JNI: Exception in MessageQueue callback: handleReceiveCallback
E/MessageQueue-JNI: java.lang.ClassCastException: androidx.constraintlayout.widget.ConstraintLayout$LayoutParams cannot be cast to android.widget.RelativeLayout$LayoutParams
    at com.example.test.MainActivity$1.onTouch(MainActivity.java:28)

Romadro was correct in saying I have a ContraintLayout in my activity_main.XML. I didn't realize that contraintLayout was the default, and I just needed to change it to relativeLayout. — Justin Kim
– Justin Kim, Commented Sep 18, 2019 at 22:20

Romadro · Accepted Answer · 2019-09-17 18:34:24Z

2

I suppose in your activity_main.xml you have ConstraintLayout with TextView inside it, so your should use ConstraintLayout.LayoutParams in your java-code instead. Or you may change ConstraintLayout to RelativeLayout in your activity_main.xml. It depends on what you are trying to implement

answered Sep 17, 2019 at 18:34

Romadro

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