Button variable turns to null after calling method

Question

In my mainactivity I have the following snip

MainActivity.class

private Button btnx10;

@Override
protected void onCreate(Bundle savedInstanceState) {
         


        

Answer 1

You are declaring Button btnx10 twice. Remove the local declaration. You should declare outside the method, and define inside the method.

Class MainActivity...
private Button btnx10;

@Override
protected void onCreate(Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);
    ...
    btnx10=(Button)findViewById(R.id.MainCOPbtn); //MINOR CORRECTION IN THIS LINE
    DrawLines()    
}

private void drawLines() {
     float centerYOnImage1=btnx10.getHeight()/2;
}