How to use paint() such that when repaint() is called the previously drawn object should not get deleted when drawing the new object. That is the drawing area must get UPDATED only and not REDRAWN.

In my code when one of many button is clicked, some aplhabet get displayed. I want to have functionality such that when other buttons are clicked the previously drawn alhabets must be present.Take is as if a string of alphabets getting created as the buttons are clicked. Im using Java Swing for coding.

Some piece of my code:

if(source == btnAlpha[i] )  
bollyDraw.repaint(); //bollydraw is an object of a JPanel extended class having implemented the paintComponent(Graphics g) method

In the paint() method:

if (word[i] == key) {
g.drawChars(word, i, 1, x, y);
}