Why this image background is black ?

Code:

---

public void drawShape(int w, int h){
    Graphics2D graphics2D ;
   
 
    BufferedImage bufferedImage = new BufferedImage( 45, 56, BufferedImage.TYPE_INT_ARGB );
    File imgFile = new File("C:\\test.jpg");
 
    graphics2D = bufferedImage .createGraphics();
    graphics2D .setBackground(Color.WHITE);
    graphics2D .setColor( Color.WHITE );
 
    try {
    ImageIO.write( bufferedImage , "jpg", imgFile );
    } catch ( IOException e ) {
            e.printStackTrace();
    }
}

---

Code:

---

graphics2D .setColor( Color.WHITE );
graphics2D .fillRect(0,0,45,56);

---