使用我的JPanel的java问题

Question

我正在用Netbeans制作一个图形界面，你可以把一系列数字（例如：7 8 5 4 10 13）放在文本字段“punten”中，当你按下按钮“ververs”时，所有数字的图形线条图就会出现（在我的面板中）。我制作了一个类“Gui”，它通过文本字段、按钮和面板扩展了JFrame。我还创建了一个类“Grafiek”，它扩展了JPanel，并与我的“Gui”中的面板相链接。图表将显示在JFrame中显示的JPanel上

我遇到的问题是：重新油漆（）；命令不会转到paintComponent（Graphics g）-方法，我的私有变量也不会改变（无论我在文本框中输入了什么变量，punt和punti的长度都保持为1）

谁能帮帮我吗？我已经做这个项目好几天了

我的Gui类：

package grafiek;

import java.awt.Graphics;
import javax.swing.JPanel;

public class Gui extends javax.swing.JFrame {

private Grafiek newJPanel;

/**
 * Creates new form Gui
 */
public Gui() {
    initComponents();
    newJPanel = new Grafiek();
}

/**
 * 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() {

    punten = new javax.swing.JTextField();
    fout = new javax.swing.JLabel();
    javax.swing.JButton ververs = new javax.swing.JButton();
    panel = new Grafiek();

    setDefaultCloseOperation(javax.swing.WindowConstants.EXIT_ON_CLOSE);

    fout.setText("j");

    ververs.setText("Ververs");
    ververs.addActionListener(new java.awt.event.ActionListener() {
        public void actionPerformed(java.awt.event.ActionEvent evt) {
            verversActionPerformed(evt);
        }
    });

    panel.setBorder(javax.swing.BorderFactory.createLineBorder(new java.awt.Color(0, 0, 0), 2));

    javax.swing.GroupLayout panelLayout = new javax.swing.GroupLayout(panel);
    panel.setLayout(panelLayout);
    panelLayout.setHorizontalGroup(
        panelLayout.createParallelGroup(javax.swing.GroupLayout.Alignment.LEADING)
        .addGap(0, 0, Short.MAX_VALUE)
    );
    panelLayout.setVerticalGroup(
        panelLayout.createParallelGroup(javax.swing.GroupLayout.Alignment.LEADING)
        .addGap(0, 195, Short.MAX_VALUE)
    );

    javax.swing.GroupLayout layout = new javax.swing.GroupLayout(getContentPane());
    getContentPane().setLayout(layout);
    layout.setHorizontalGroup(
        layout.createParallelGroup(javax.swing.GroupLayout.Alignment.LEADING)
        .addGroup(javax.swing.GroupLayout.Alignment.TRAILING, layout.createSequentialGroup()
            .addContainerGap()
            .addGroup(layout.createParallelGroup(javax.swing.GroupLayout.Alignment.TRAILING)
                .addComponent(panel, javax.swing.GroupLayout.DEFAULT_SIZE, javax.swing.GroupLayout.DEFAULT_SIZE, Short.MAX_VALUE)
                .addComponent(punten, javax.swing.GroupLayout.Alignment.LEADING)
                .addGroup(javax.swing.GroupLayout.Alignment.LEADING, layout.createSequentialGroup()
                    .addComponent(ververs)
                    .addGap(6, 6, 6)
                    .addComponent(fout)
                    .addGap(0, 302, Short.MAX_VALUE)))
            .addContainerGap())
    );
    layout.setVerticalGroup(
        layout.createParallelGroup(javax.swing.GroupLayout.Alignment.LEADING)
        .addGroup(layout.createSequentialGroup()
            .addContainerGap()
            .addComponent(punten, javax.swing.GroupLayout.PREFERRED_SIZE, javax.swing.GroupLayout.DEFAULT_SIZE, javax.swing.GroupLayout.PREFERRED_SIZE)
            .addGap(18, 18, 18)
            .addComponent(panel, javax.swing.GroupLayout.DEFAULT_SIZE, javax.swing.GroupLayout.DEFAULT_SIZE, Short.MAX_VALUE)
            .addGap(18, 18, 18)
            .addGroup(layout.createParallelGroup(javax.swing.GroupLayout.Alignment.BASELINE)
                .addComponent(fout)
                .addComponent(ververs))
            .addContainerGap())
    );

    pack();
}// </editor-fold>                        

private void verversActionPerformed(java.awt.event.ActionEvent evt) {                                        
    newJPanel.verwerkData(punten.getText());
}                                       

/**
 * @param args the command line arguments
 */
public static void main(String args[]) {
    /* Set the Nimbus look and feel */
    //<editor-fold defaultstate="collapsed" desc=" Look and feel setting code (optional) ">
    /* If Nimbus (introduced in Java SE 6) is not available, stay with the default look and feel.
     * For details see http://download.oracle.com/javase/tutorial/uiswing/lookandfeel/plaf.html 
     */
    try {
        for (javax.swing.UIManager.LookAndFeelInfo info : javax.swing.UIManager.getInstalledLookAndFeels()) {
            if ("Nimbus".equals(info.getName())) {
                javax.swing.UIManager.setLookAndFeel(info.getClassName());
                break;
            }
        }
    } catch (ClassNotFoundException ex) {
        java.util.logging.Logger.getLogger(Gui.class.getName()).log(java.util.logging.Level.SEVERE, null, ex);
    } catch (InstantiationException ex) {
        java.util.logging.Logger.getLogger(Gui.class.getName()).log(java.util.logging.Level.SEVERE, null, ex);
    } catch (IllegalAccessException ex) {
        java.util.logging.Logger.getLogger(Gui.class.getName()).log(java.util.logging.Level.SEVERE, null, ex);
    } catch (javax.swing.UnsupportedLookAndFeelException ex) {
        java.util.logging.Logger.getLogger(Gui.class.getName()).log(java.util.logging.Level.SEVERE, null, ex);
    }
    //</editor-fold>

    /* Create and display the form */
    java.awt.EventQueue.invokeLater(new Runnable() {
        public void run() {
            new Gui().setVisible(true);
        }
    });
}

// Variables declaration - do not modify                     
private javax.swing.JLabel fout;
private javax.swing.JPanel panel;
private javax.swing.JTextField punten;
// End of variables declaration                   
}

我的格拉菲克班：

package grafiek;

import java.awt.Graphics;

public class Grafiek extends javax.swing.JPanel {

private String[] punt;
private int[] punti;
private int afstandX, afstandY, puntX1, puntY1, puntX2, puntY2;
private int max;

/**
 * Creates new form Grafiek
 */
public Grafiek() {
    initComponents();
    punt = new String[1];
    punti = new int[1];
    afstandX = 0;
    afstandY = 0;
    puntX1 = 0; 
    puntY1 = 0; 
    puntX2 = 0; 
    puntY2 = 0;
    max = 1;
}

@Override
public void paintComponent(Graphics g) {
    super.paintComponent(g);

    for(int i=0; i<punti.length; i++) {
        if(max <= punti[i]) {
            max = punti[i];
        }
    }

    afstandX = getWidth()/punt.length;
    afstandY = getHeight()/max;

    for(int i=0; i<punti.length; i++) {
        puntX1 = puntX2;
        if(i == 0) {
            puntY1 = getHeight();
        }
        else puntY1 = puntY2;
        puntX2 += afstandX;
        puntY2 = getHeight() - punti[i]*afstandY;

        g.drawLine(puntX1, puntY1, puntX2, puntY2);
    }

    puntX2 = 0;
}

public void verwerkData(String s) {
    punt = s.split(" ");

    punti = new int[punt.length];

    for(int i=0; i<punt.length; i++) {
        punti[i] = Integer.parseInt(punt[i]);
    }

    repaint();
}

/**
 * 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() {

    setBackground(new java.awt.Color(255, 255, 255));

    javax.swing.GroupLayout layout = new javax.swing.GroupLayout(this);
    this.setLayout(layout);
    layout.setHorizontalGroup(
        layout.createParallelGroup(javax.swing.GroupLayout.Alignment.LEADING)
        .addGap(0, 400, Short.MAX_VALUE)
    );
    layout.setVerticalGroup(
        layout.createParallelGroup(javax.swing.GroupLayout.Alignment.LEADING)
        .addGap(0, 300, Short.MAX_VALUE)
    );
}// </editor-fold>                        

}

Answer 1

我看到的一个问题是，您已经声明了一个实例化的

newJPanel = new Grafiek();

哪个是在action方法中调用的对象

private void verversActionPerformed(java.awt.event.ActionEvent evt) {                                        
    newJPanel.verwerkData(punten.getText());
} 

但是newJPanel永远不会添加到帧中。看起来要添加到帧中的对象是

panel = new Grafiek();

在initComponents()中。试着改变

newJPanel.verwerkData(punten.getText());

到

panel.verwerkData(punten.getText());

扔掉newJpanel，因为你从来不使用它