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这段代码我真的快疯了。我需要知道我做错了什么？我应该得到 3 个文本字段和一个文本区域显示，当我执行时，我只得到一个灰色框。我看不到文本字段和文本区域，甚至看不到按钮。怎么了？为什么我的 JFrame 是空白的？！谢谢

这是我的代码：

import javax.swing.JFrame;
import javax.swing.JPanel;
import javax.swing.JTextArea;
import javax.swing.JTextField;
import java.lang.Integer;



public class MinVara extends javax.swing.JFrame {

    //Skapar upp instans variabler (instansvariabler in the body of the class
    //but outside the bodies of the class methods

  private String namn;
  private int nummer;
 private double pris; 



    //Skapar konstruktor för minvara.Like amethod, a constructor’s parameterlist 
 //specifies the data it requires to perform its task
 //An important difference between constructors and methods is that constructors
//cannot return values, so they cannot specify a return type 
 //(not even void). Normally, constructors are declared public.

 public MinVara(String namn, int nummer, double pris) { 
        this.namn = namn; //this "Det här objektet name"
        this.nummer = nummer; //"" 
        this.pris = pris;//""

       // slut constructor 
        initComponents();
     }



    //Skapa ett nytt minvara objekt genom att kalla på en konstruktor
     MinVara var = new MinVara(namn, nummer, pris); //


    @Override
public void setName(String namn)  {  
        this.namn = namn; } //store the string name

 public void setAntal (int nummer)  {  
        this.nummer = nummer;  }

    public void  setPrice (double pris) { 
        this.pris = pris; } 



    @Override
    public String getName() {    
        return this.namn;} 


    public int getAntal() {    
        return this.nummer; }     

    public double getPrice() {   
        return this.pris; } 


    /**
     * 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() {

        jColorChooser1 = new javax.swing.JColorChooser();
        jColorChooser2 = new javax.swing.JColorChooser();
        jPanel1 = new javax.swing.JPanel();
        jScrollPane1 = new javax.swing.JScrollPane();
        jTextArea1 = new javax.swing.JTextArea();
        jTextField1 = new javax.swing.JTextField();
        jTextField2 = new javax.swing.JTextField();
        jTextField3 = new javax.swing.JTextField();
        jButton1 = new javax.swing.JButton();
        jLabel1 = new javax.swing.JLabel();
        jLabel2 = new javax.swing.JLabel();
        jLabel3 = new javax.swing.JLabel();

        setDefaultCloseOperation(javax.swing.WindowConstants.EXIT_ON_CLOSE);

        jTextArea1.setColumns(20);
        jTextArea1.setRows(5);
        jScrollPane1.setViewportView(jTextArea1);

        jTextField2.addActionListener(new java.awt.event.ActionListener() {
            public void actionPerformed(java.awt.event.ActionEvent evt) {
                jTextField2ActionPerformed(evt);
            }
        });

        jButton1.setText("OK");
        jButton1.addActionListener(new java.awt.event.ActionListener() {
            public void actionPerformed(java.awt.event.ActionEvent evt) {
                jButton1ActionPerformed(evt);
            }
        });

        jLabel1.setText("Namn");

        jLabel2.setText("Pris");

        jLabel3.setText("Antal");

        javax.swing.GroupLayout jPanel1Layout = new javax.swing.GroupLayout(jPanel1);
        jPanel1.setLayout(jPanel1Layout);
        jPanel1Layout.setHorizontalGroup(
            jPanel1Layout.createParallelGroup(javax.swing.GroupLayout.Alignment.LEADING)
            .addGroup(javax.swing.GroupLayout.Alignment.TRAILING, jPanel1Layout.createSequentialGroup()
                .addGroup(jPanel1Layout.createParallelGroup(javax.swing.GroupLayout.Alignment.LEADING)
                    .addComponent(jTextField1, javax.swing.GroupLayout.PREFERRED_SIZE, 90, javax.swing.GroupLayout.PREFERRED_SIZE)
                    .addComponent(jTextField2, javax.swing.GroupLayout.PREFERRED_SIZE, 90, javax.swing.GroupLayout.PREFERRED_SIZE)
                    .addComponent(jLabel2)
                    .addComponent(jLabel3)
                    .addComponent(jLabel1)
                    .addComponent(jTextField3, javax.swing.GroupLayout.PREFERRED_SIZE, 90, javax.swing.GroupLayout.PREFERRED_SIZE)
                    .addComponent(jButton1, javax.swing.GroupLayout.PREFERRED_SIZE, 67, javax.swing.GroupLayout.PREFERRED_SIZE))
                .addPreferredGap(javax.swing.LayoutStyle.ComponentPlacement.RELATED, 44, Short.MAX_VALUE)
                .addComponent(jScrollPane1, javax.swing.GroupLayout.PREFERRED_SIZE, 239, javax.swing.GroupLayout.PREFERRED_SIZE)
                .addGap(27, 27, 27))
        );
        jPanel1Layout.setVerticalGroup(
            jPanel1Layout.createParallelGroup(javax.swing.GroupLayout.Alignment.LEADING)
            .addGroup(jPanel1Layout.createSequentialGroup()
                .addGroup(jPanel1Layout.createParallelGroup(javax.swing.GroupLayout.Alignment.LEADING)
                    .addGroup(jPanel1Layout.createSequentialGroup()
                        .addContainerGap()
                        .addComponent(jScrollPane1, javax.swing.GroupLayout.PREFERRED_SIZE, 249, javax.swing.GroupLayout.PREFERRED_SIZE))
                    .addGroup(jPanel1Layout.createSequentialGroup()
                        .addComponent(jLabel1)
                        .addGap(8, 8, 8)
                        .addComponent(jTextField2, javax.swing.GroupLayout.PREFERRED_SIZE, javax.swing.GroupLayout.DEFAULT_SIZE, javax.swing.GroupLayout.PREFERRED_SIZE)
                        .addGap(18, 18, 18)
                        .addComponent(jLabel2)
                        .addGap(8, 8, 8)
                        .addComponent(jTextField3, javax.swing.GroupLayout.PREFERRED_SIZE, javax.swing.GroupLayout.DEFAULT_SIZE, javax.swing.GroupLayout.PREFERRED_SIZE)
                        .addGap(18, 18, 18)
                        .addComponent(jLabel3)
                        .addPreferredGap(javax.swing.LayoutStyle.ComponentPlacement.UNRELATED)
                        .addComponent(jTextField1, javax.swing.GroupLayout.PREFERRED_SIZE, javax.swing.GroupLayout.DEFAULT_SIZE, javax.swing.GroupLayout.PREFERRED_SIZE)
                        .addGap(37, 37, 37)
                        .addComponent(jButton1, javax.swing.GroupLayout.PREFERRED_SIZE, 33, javax.swing.GroupLayout.PREFERRED_SIZE)))
                .addContainerGap(40, Short.MAX_VALUE))
        );

        javax.swing.GroupLayout layout = new javax.swing.GroupLayout(getContentPane());
        getContentPane().setLayout(layout);
        layout.setHorizontalGroup(
            layout.createParallelGroup(javax.swing.GroupLayout.Alignment.LEADING)
            .addComponent(jPanel1, javax.swing.GroupLayout.DEFAULT_SIZE, javax.swing.GroupLayout.DEFAULT_SIZE, Short.MAX_VALUE)
        );
        layout.setVerticalGroup(
            layout.createParallelGroup(javax.swing.GroupLayout.Alignment.LEADING)
            .addComponent(jPanel1, javax.swing.GroupLayout.DEFAULT_SIZE, javax.swing.GroupLayout.DEFAULT_SIZE, Short.MAX_VALUE)
        );

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

    private void jButton1ActionPerformed(java.awt.event.ActionEvent evt) {                                         

 jTextArea1.setText(null); //tömmer textarean

//variablar till textfälten. omvandla string till int och double.
 this.namn =  jTextField1.getText();
 var.setName(namn);
 jTextArea1.append("Namnet på varan : " +var.getName());

 this.nummer  = Integer.parseInt( jTextField3.getText() );
var.setAntal(nummer);
 jTextArea1.append("Antal varor : " + var.getAntal() );

 this.pris = Double.parseDouble(jTextField2.getText() );
 var.setPrice(pris);
 jTextArea1.append("Pris : " + var.getPrice());







    }                                        

    private void jTextField2ActionPerformed(java.awt.event.ActionEvent evt) {                                            

    }                                           

    /**
     * @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(MinVara.class.getName()).log(java.util.logging.Level.SEVERE, null, ex);
        } catch (InstantiationException ex) {
            java.util.logging.Logger.getLogger(MinVara.class.getName()).log(java.util.logging.Level.SEVERE, null, ex);
        } catch (IllegalAccessException ex) {
            java.util.logging.Logger.getLogger(MinVara.class.getName()).log(java.util.logging.Level.SEVERE, null, ex);
        } catch (javax.swing.UnsupportedLookAndFeelException ex) {
            java.util.logging.Logger.getLogger(MinVara.class.getName()).log(java.util.logging.Level.SEVERE, null, ex);
        }
        //</editor-fold>

        /*
         * Create and display the form
         */
        java.awt.EventQueue.invokeLater(new Runnable() {
            @Override
            public void run() {
            JFrame frame = new JFrame("Resultat");
            JPanel jPanel1 = new JPanel();

            frame.getContentPane().add(jPanel1);
            frame.pack();

       frame.setSize(400,400);
          frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
      frame.setVisible(true);

            }
        });
    }
    // Variables declaration - do not modify                     
    private javax.swing.JButton jButton1;
    private javax.swing.JColorChooser jColorChooser1;
    private javax.swing.JColorChooser jColorChooser2;
    private javax.swing.JLabel jLabel1;
    private javax.swing.JLabel jLabel2;
    private javax.swing.JLabel jLabel3;
    private javax.swing.JPanel jPanel1;
    private javax.swing.JScrollPane jScrollPane1;
    private javax.swing.JTextArea jTextArea1;
    private javax.swing.JTextField jTextField1;
    private javax.swing.JTextField jTextField2;
    private javax.swing.JTextField jTextField3;
    // End of variables declaration                   
}
4

1 回答 1

5

可能是因为这段代码：

        JFrame frame = new JFrame("Resultat");
        JPanel jPanel1 = new JPanel();

        frame.getContentPane().add(jPanel1);
        frame.pack();

   frame.setSize(400,400);
      frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
  frame.setVisible(true);

您正在向您的 JFrame 添加一个空白面板，之后您不会对其进行修改。你的类扩展了一个 JFrame，但我没有看到你试图展示MinVara. 也许你的意思是JFrame frame = new MinVara(...)在这里说。

于 2013-07-08T19:10:04.010 回答