Create a buffered image that supports transparency : BufferedImage « 2D Graphics « Java Tutorial

1. Java Tutorial
2. 2D Graphics
3. BufferedImage

import java.awt.image.BufferedImage;

public class Main {
  public static void main(String[] argv) throws Exception {
    int width = 100;
    int height = 100;
    BufferedImage bimage = new BufferedImage(width, height, BufferedImage.TYPE_INT_ARGB);
  }
}