Java-JFrame没有显示多张图片

Question

So I've been trying to teach myself the basics of Java (2D) gaming. After a long, annoying process trying to get an image to display, I got it working. Unfortunately, when I tried to add a second image, it replaced the first. I know that I'm making some obvious, noob mistake, but hey, I'm a noob at this. Anyway, here's my code:

import javax.swing.ImageIcon;
import javax.swing.JFrame;
import javax.swing.JLabel;

public class Main extends JFrame {

    public static void main(String[] args0) {

        JFrame frame = new JFrame();
        ImageIcon background = new ImageIcon("background.png");
        JLabel backgroundLabel = new JLabel(background);
        frame.add(backgroundLabel);
        backgroundLabel.setVisible(true);

        ImageIcon title = new ImageIcon("title.png");
        JLabel titleLabel = new JLabel(title);
        frame.add(titleLabel);
        titleLabel.setVisible(false);

        frame.setVisible(true);
        frame.setTitle("Fastball");
        frame.setDefaultCloseOperation(EXIT_ON_CLOSE);
        frame.pack();

    }

}

When I run this, the newly added "title.png" section overrides the first image, replacing it. Please, just tell me the simplest way to fix this with a brief explanation of my mistake.

(PS I'm using Eclipse Mars and the latest of all the Java stuff.)

Answer 1

Start by taking a look at How to Use BorderLayout to understand why the problem is occurring and then have a look at Laying Out Components Within a Container for some possible solutions

JFrame frame = new JFrame();
//...
frame.setContentPane(backgroundLabel);
frame.setLayout(new GridBagLayout());

ImageIcon title = new ImageIcon("title.png");
JLabel titleLabel = new JLabel(title);
frame.add(titleLabel);
//...

You should be adding your titleLabel to the backgroundLabel , but you can "cheat" a little with JFrame , you can set the backgroundLabel as the "content pane" of the frame, this means that anything you add to the frame is actually added to the backgroundLabel .

Cavets

• JLabel does not have a layout manage applied by default, this means that unless you apply one, anything you add to it will not be sized or positioned and will appear "invisible"
• JLabel does not use the layout manager to calculate it's preferred size, instead, it relies on the size of the image and it's text. This may not be an issue in most cases, but if your content, for some reason, exceeds the size of the image (either horizontally or vertically), the content will be clipped. You could have a look at this example which shows a couple of different ways to achieve the same result