如何更改JPanel的背景图片

Question

是否可以在初始化后更改 JPanel 的图像？

Block.java (JPanel 改img)

@SuppressWarnings("serial")
public class Block extends JPanel{

    private int rotation;

    public Block(){
    }

    @Override
    protected void paintComponent(Graphics g){ 
        super.paintComponent(g);    
        Graphics2D g2 = (Graphics2D) g;

        g2.drawImage(Images.greenBlock, 0, 0, null); 

    } 
}

现在我需要一个像 changeImage:

这样的方法

...
JPanel xy = new Block();

xy.changeImage(newImg); //I know this method does NOT exist

感谢您的帮助

Answer 1

改变这个：

JPanel xy = new Block();

对此：

Block xy = new Block();

并为 Block 提供一个 changeImage(newImg) 方法，您可以在其中更改变量 greenBlock 引用的图像。在您的 changeImage 方法中，不要忘记调用 repaint();

问题：为什么在您的 paintComponent 方法中使用 break; 语句？

例如，

public class Block extends JPanel{

    private int rotation;
    // if you wish to initialize it with greenBlock...
    private Image myImage = Images.greenBlock;

    public Block(){
    }

    @Override
    protected void paintComponent(Graphics g){ 
        super.paintComponent(g);    
        Graphics2D g2 = (Graphics2D) g;
        g2.drawImage(myImage, 0, 0, null);
    } 

    public void changeImage(Image img) {
        this.myImage = img;
        repaint();
    }
}

如何更改JPanel的背景图片

How to change background image of JPanel

java

swing

jpanel