'setLayoutParams on a null object reference

I learn a very simple animation sample from Book "Android Studio Development edition 6, Essentials" Chapter 29" and get an error as shown on logcat file:

java.lang.NullPointerException: Attempt to invoke virtual method 'void android.view.View.setLayoutParams(android.view.ViewGroup$LayoutParams)' on a null object reference.

My sample codes that are compiled successfully as shown below:

import android.os.Bundle;
import android.support.v7.app.AppCompatActivity;
import android.util.Log;
import android.view.MotionEvent;
import android.view.View;
import android.view.ViewGroup;
import android.widget.RelativeLayout;
import android.widget.Toast;

public class TransitionDemoActivity extends AppCompatActivity {
    ViewGroup myLayout;
    @Override
    protected void onCreate(Bundle savedInstanceState) {

        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_transition_demo);

        myLayout=(ViewGroup)findViewById(R.id.myLayout);
        myLayout.setOnTouchListener(
                new RelativeLayout.OnTouchListener() {
                    public boolean onTouch(View v, MotionEvent m) {

                        handleTouch();
                          return true;
                    }
                });

    }
    public void handleTouch() {
        Toast.makeText(this,"Touching",Toast.LENGTH_LONG).show();//for listener test

       View view = findViewById(R.id.myButton1);

        RelativeLayout.LayoutParams params = new RelativeLayout.LayoutParams
                (RelativeLayout.LayoutParams.WRAP_CONTENT,
                RelativeLayout.LayoutParams.WRAP_CONTENT);

       params.addRule(RelativeLayout.ALIGN_PARENT_RIGHT,
                RelativeLayout.TRUE);
        params.addRule(RelativeLayout.ALIGN_PARENT_BOTTOM,
                RelativeLayout.TRUE);

       **view.setLayoutParams(params);**

        ViewGroup.LayoutParams lparams = view.getLayoutParams();

        lparams.width = 500;
        lparams.height = 350;
        view.setLayoutParams(lparams);
    }
}

I trace the code line to find the error code location on "view.setLayoutParams(params), but I just can't resolve this issue. Anyone can help me. Thanks

javaandroid


Solution 1:[1]

This means that your View myButton1 did not exist and so your line View view = findViewById(R.id.myButton1); returned null. Make sure you actually have a Button or some other view with the id myButton1 assigned in your layout xml file.

Sources

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Source: Stack Overflow

Solution Source
Solution 1 NoChinDeluxe

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