Java Netbeans - 如何在 Jpanel 内的 Jpanel 上绘图？（面板构造器）

Question

我正在努力学习 Java，现在我遇到了 Jpanels，并且由于我使用的是 Netbeans，所以我可以使用他们的 "constructor"，在其中我可以在我的框架内设计我想要的面板。

我用 netbeans 在我的面板中做了一个面板，现在我想知道：

如何在面板内的面板上绘图？

(我要画的面板是EvoPanel)

This is my current design

深灰色框是面板内的第二个面板，如果我尝试从左上角到右下角画一条线，我最终会得到 this

我的代码：

Vindue.java

package vindue;
import javax.swing.*;

/**
 *
 * @author BE56df
 */
public class Vindue {

    /**
     * @param args the command line arguments
     */
    public static void main(String[] args) {
        // TODO code application logic here

        paneler panel = new paneler();

        JFrame vindue = new JFrame("NEZ - Evolution Simulator v0.1");
        vindue.add(panel);

        vindue.setDefaultCloseOperation(JFrame.DISPOSE_ON_CLOSE);

        vindue.setResizable(false);
        vindue.pack();
        vindue.setVisible(true);

    }

}

Paneler.java

package vindue;
import java.awt.*;
import javax.swing.*;

/**
 *
 * @author BE56df
 */
public class paneler extends javax.swing.JPanel {

    /**
     * Creates new form paneler
     */
    public paneler() {
        initComponents();
    }

    public void paintComponent(Graphics g){

        super.paintComponent(g);

        g.drawLine(0, 0, 750, 550);

    }

    /**
     * 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")
    // <editor-fold defaultstate="collapsed" desc="Generated Code">                          
    private void initComponents() {

        EvoPanel = new javax.swing.JPanel();
        jLabel1 = new javax.swing.JLabel();
        jSeparator1 = new javax.swing.JSeparator();
        jToggleButton1 = new javax.swing.JToggleButton();

        setMaximumSize(new java.awt.Dimension(750, 550));
        setMinimumSize(new java.awt.Dimension(750, 550));
        setPreferredSize(new java.awt.Dimension(750, 550));

        EvoPanel.setBackground(new java.awt.Color(200, 200, 200));
        EvoPanel.setMaximumSize(new java.awt.Dimension(550, 550));
        EvoPanel.setMinimumSize(new java.awt.Dimension(550, 550));

        javax.swing.GroupLayout EvoPanelLayout = new javax.swing.GroupLayout(EvoPanel);
        EvoPanel.setLayout(EvoPanelLayout);
        EvoPanelLayout.setHorizontalGroup(
            EvoPanelLayout.createParallelGroup(javax.swing.GroupLayout.Alignment.LEADING)
            .addGap(0, 550, Short.MAX_VALUE)
        );
        EvoPanelLayout.setVerticalGroup(
            EvoPanelLayout.createParallelGroup(javax.swing.GroupLayout.Alignment.LEADING)
            .addGap(0, 550, Short.MAX_VALUE)
        );

        jLabel1.setFont(new java.awt.Font("Tahoma", 1, 11)); // NOI18N
        jLabel1.setText("Control panel");
        jLabel1.setVerticalAlignment(javax.swing.SwingConstants.BOTTOM);
        jLabel1.setVerticalTextPosition(javax.swing.SwingConstants.BOTTOM);

        jToggleButton1.setText("Auto play");

        javax.swing.GroupLayout layout = new javax.swing.GroupLayout(this);
        this.setLayout(layout);
        layout.setHorizontalGroup(
            layout.createParallelGroup(javax.swing.GroupLayout.Alignment.LEADING)
            .addGroup(layout.createSequentialGroup()
                .addComponent(EvoPanel, javax.swing.GroupLayout.PREFERRED_SIZE, javax.swing.GroupLayout.DEFAULT_SIZE, javax.swing.GroupLayout.PREFERRED_SIZE)
                .addGroup(layout.createParallelGroup(javax.swing.GroupLayout.Alignment.TRAILING)
                    .addGroup(javax.swing.GroupLayout.Alignment.LEADING, layout.createSequentialGroup()
                        .addGap(63, 63, 63)
                        .addComponent(jLabel1)
                        .addGap(0, 58, Short.MAX_VALUE))
                    .addGroup(layout.createSequentialGroup()
                        .addPreferredGap(javax.swing.LayoutStyle.ComponentPlacement.RELATED, javax.swing.GroupLayout.DEFAULT_SIZE, Short.MAX_VALUE)
                        .addGroup(layout.createParallelGroup(javax.swing.GroupLayout.Alignment.LEADING, false)
                            .addComponent(jSeparator1, javax.swing.GroupLayout.DEFAULT_SIZE, 190, Short.MAX_VALUE)
                            .addComponent(jToggleButton1, javax.swing.GroupLayout.DEFAULT_SIZE, javax.swing.GroupLayout.DEFAULT_SIZE, Short.MAX_VALUE))))
                .addContainerGap())
        );
        layout.setVerticalGroup(
            layout.createParallelGroup(javax.swing.GroupLayout.Alignment.LEADING)
            .addComponent(EvoPanel, javax.swing.GroupLayout.PREFERRED_SIZE, javax.swing.GroupLayout.DEFAULT_SIZE, javax.swing.GroupLayout.PREFERRED_SIZE)
            .addGroup(layout.createSequentialGroup()
                .addComponent(jLabel1, javax.swing.GroupLayout.PREFERRED_SIZE, 20, javax.swing.GroupLayout.PREFERRED_SIZE)
                .addPreferredGap(javax.swing.LayoutStyle.ComponentPlacement.RELATED)
                .addComponent(jSeparator1, javax.swing.GroupLayout.PREFERRED_SIZE, 10, javax.swing.GroupLayout.PREFERRED_SIZE)
                .addPreferredGap(javax.swing.LayoutStyle.ComponentPlacement.RELATED)
                .addComponent(jToggleButton1))
        );
    }// </editor-fold>                        


    // Variables declaration - do not modify                     
    private javax.swing.JPanel EvoPanel;
    private javax.swing.JLabel jLabel1;
    private javax.swing.JSeparator jSeparator1;
    private javax.swing.JToggleButton jToggleButton1;
    // End of variables declaration                   
}

Answer 1

很明显，当您真的想在 EvoPanel 上绘制时，您在主 JFrame（面板面板）上绘制了线条。您应该创建一个 class EvoPanel（使用 paintComponent 方法）并在 paneler#initComponents.

之后添加

public paneler() {
  initComponents();
  EvoPanel evoPanel = new EvoPanel();
  add(evoPanel) // properly in a layout
}

建议：对于简单的 GUI，不要使用 Mantisse（Netbeans GUI 构建工具），它不会给您带来任何好处。

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