使用图形时如何处理私人空白？

Question

So I've been trying to figure this out, and I'm not sure how... I've been working on this piece of code here:

public class Main extends JPanel {


public void paintComponent(Graphics g) {
    super.paintComponent(g);
    drawGrass(g);
    drawFlowers(g);
    
}

private void drawGrass(Graphics g) {
    super.paintComponent(g);

    Color brightGreen= new Color(60,176,31);
    g.setColor(brightGreen);
  
    g.setColor(brightGreen);
    g.fillRect(0,300,500,500); 
}

 private void drawFlowers(Graphics g) {
    super.paintComponent(g);
    Color pinkFlower = new Color(225,153,153);
    g.setColor(pinkFlower);
    g.fillRect(25,320,8,8);
    g.fillRect(320,380,8,8);
    g.fillRect(110,355,8,8);

}

I figured out that it will only draw the flowers because it overrides over the drawGrass. How would I make it so it doesn't override my other code?

Answer 1

Start simpler. If you only use one method, it should work fine.

public class Main extends JPanel {

    @Override
    public void paintComponent(Graphics g) {
        super.paintComponent(g);
        // draw grass
        Color brightGreen= new Color(60,176,31);
        ...
        // draw flower
        Color pinkFlower = new Color(225,153,153);
        ...
    }

}

So if you want to extract the two colors and drawings into methods, you only need to copy those exact lines between the comments (you can even use your IDE features to "Extract Method"), not add another super.paintComponent(g) (which is what is clearing the panel)

Regarding the question title, private void isn't the issue or related to the solution, really.

Answer 2

The problem is on your super.paintComponent(g) on the fist line of drawFlowers method (and duplicated on drawGrass method). You can't do that. Remove it, try again, and it will work. Remember, when you call one method inside another method, all your code is like "inside the fist method"... So, your code now is like

public void paintComponent(Graphics g) {
    super.paintComponent(g);//fist call.
    super.paintComponent(g);//duplicated, delete it on drawGrass method.
    Color brightGreen= new Color(60,176,31);
    g.setColor(brightGreen);
    g.setColor(brightGreen);
    g.fillRect(0,300,500,500); 
    super.paintComponent(g);//this is biggest problem, this overrides all work, remove it.
    Color pinkFlower = new Color(225,153,153);
    g.setColor(pinkFlower);
    g.fillRect(25,320,8,8);
    g.fillRect(320,380,8,8);
    g.fillRect(110,355,8,8);    
}