java - 如何在 JFrames 中使用 2 类绘制通过 Netbeans 中的 Palette 生成代码？

Question

public class DrawST extends javax.swing.JFrame {

    /**
     * Creates new form DrawST
     */
    
    
    public DrawST() {
        initComponents();
    }
    
    /**
     * This method is called from within the constructor to initialize the form.
     * WARNING: Do NOT modify this code. The content of this method is always
     * regenerated by the Form Editor.
     */
    @SuppressWarnings("unchecked")
    Generated code
     /**
     * @param args the command line arguments
     */
    public static void main(String args[]) {
        /* Set the Nimbus look and feel */
        /* Create and display the form */
        java.awt.EventQueue.invokeLater(new Runnable() {
            public void run() {
                new DrawST().setVisible(true);
            }
        });
    }
    class Class01 extends JPanel{
       @Override
       public void paintComponent(Graphics g) {
           super.paintComponent(g);
       }
    }
    class Class02 extends JPanel{
        @Override
        public void paintComponent(Graphics g){
            super.paintComponent(g);
        }
    }
    // Variables declaration - do not modify                     
    // End of variables declaration                   
}

如何同时使用Class01和Class02在此JFrame中进行绘制，Class01将绘制管道，Class02 code> 将画 Frog (快乐 Frog )。我尝试创建 Container contains = getContentPane(); 并添加两个类。但它只能添加 1 个类。如果我添加两个类，JFrame 将不会绘制任何内容。

Answer 1

您犯了一个常见的错误:创建扩展 Swing 组件的绘图类，而它们应该是逻辑类，而不是组件类:

• 如果您正在制作动画，通常只有一个组件，通常由 JPanel 进行绘图，这意味着 paintComponent 方法在一个组件中被重写。
• 如果您希望一个类来绘制特定的 Sprite ，例如 Frog 或管道，那么这些 Sprite 将在上述相同的单个绘图类中绘制。
• 组件类，即扩展 Swing GUI 组件(例如 JPanel)的类，通常作为组件放置在 GUI 中 - GUI 的构建 block ，放置在 GUI 中的有限位置，并且仅绘制自身及其子组件。
• 因此，要绘制多个 Sprite 占据相同绘图空间的绘图，创建这些 Sprite 的类不应该扩展 JPanel 或类似的 Swing 组件，而应该只是逻辑类(不是组件的类) )，然后由单个绘图 JPanel 绘制。

例如

public class DrawST extends javax.swing.JFrame {

    
    public DrawST() {
        // add the DrawingPanel to the JFrame here
    }
    
}

// this class extends JPanel and does *all* the drawing
public class DrawingPanel extends JPanel {
    private Frog frog = new Frog(0, 0);
    private List<Pipe> pipes = new ArrayList<>();
    private Timer timer; // you'll probably need a Swing Timer to drive the animation
    
    // a single paintComponent method is present
    protected void paintComponent(Graphics g) {
        super.paintComponent(g);  // Don't forget this
        frog.draw(g);  // have this component draw a frog
        for (Pipe pipe : pipes) {
            pipe.draw(g);  // draw all the pipes
        }
    }

}

// does not extend JPanel
public class Frog {
    private int x;
    private int y;
    
    public Frog(int x, int y) {
        this.x = x;
        this.y = y;
    }
    
    public void draw(Graphics g) {
        // use x, y, and g to draw a frog at x,y location 
    }
}

// does not extend JPanel (not sure what a pipe is, TBH)
public class Pipe {
    private int x;
    private int y;
    // other? length, color, width?
    
    public void draw(Graphics g) {
        // use x, y, and g to draw a pipe. 
        // maybe also needs a length, color, width?
    }
}