Question

Here i am creating 20 Button dynamically using for loop

exmple

for(int i =1 ;i <= 20 ;i++){
Button b = new Button(this);
b.setText(String.valueOf(i));
b.setId(String.valueOf(i));
b.setBackgroudColor(Color.Red);

b.setOnClickListener(new View.OnClickListener() {
        public void onClick(View v) {

            b.setBackgroundColor(Color.GREEN);


        }
);

}

If i select 1st Button color will be changing to green remaining all are red. similarly if i select 2nd Button 1st and 2nd button color will be green and remaining all are red. this is the way it working fine .but my requirement is if i select the any button 2nd time all buttons and previous button which i pressed color should be red. to do that i am not getting the previous button id’s. can any help for this problem

Answer 1

Hold a reference of the previously pressed button:

final Button prevButton;
for(int i =1 ;i <= 20 ;i++){
    Button b = new Button(this);    
    b.setText(String.valueOf(i));
    b.setId(String.valueOf(i));
    b.setBackgroudColor(Color.Red);

    b.setOnClickListener(new View.OnClickListener() {
            public void onClick(View v) {

                if(prevButton != null)
                    prevButton.setBackgroundColor(Color.RED);
                b.setBackgroundColor(Color.GREEN);
                prevButton = (Button)v;
            }
    );
}