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我是java的初學(xué)者.我在java(NetBeans)中創(chuàng)建了一個JPanel表單.然后,我定義了一些動作,如數(shù)學(xué)計算.當(dāng)我運(yùn)行我的項目時,我沒有收到任何錯誤,但我在運(yùn)行時看不到JPanel表單.因為我沒有在主類中定義jform.如何在主類中定義JPanel表單以在運(yùn)行時向我顯示JPanel表單.
public class NewJPanel extends javax.swing.JPanel {
public NewJPanel() {
initComponents();
}
@SuppressWarnings("unchecked")
// <editor-fold defaultstate="collapsed" desc="Generated Code">
private void initComponents() {
jLabel1 = new javax.swing.JLabel();
jLabel2 = new javax.swing.JLabel();
jLabel3 = new javax.swing.JLabel();
jTextField1 = new javax.swing.JTextField();
jTextField2 = new javax.swing.JTextField();
jTextField3 = new javax.swing.JTextField();
jButton1 = new javax.swing.JButton();
jButton2 = new javax.swing.JButton();
jButton3 = new javax.swing.JButton();
jButton4 = new javax.swing.JButton();
jButton5 = new javax.swing.JButton();
jLabel1.setText("First Number:");
jLabel2.setText("Second Number:");
jLabel3.setText("Result:");
jButton1.setText("Add");
jButton1.addActionListener(new java.awt.event.ActionListener() {
public void actionPerformed(java.awt.event.ActionEvent evt) {
jButton1ActionPerformed(evt);
}
});
jButton2.setText("Subtract");
jButton2.addActionListener(new java.awt.event.ActionListener() {
public void actionPerformed(java.awt.event.ActionEvent evt) {
jButton2ActionPerformed(evt);
}
});
jButton3.setText("Multiply");
jButton3.addActionListener(new java.awt.event.ActionListener() {
public void actionPerformed(java.awt.event.ActionEvent evt) {
jButton3ActionPerformed(evt);
}
});
jButton4.setText("Divide");
jButton4.addActionListener(new java.awt.event.ActionListener() {
public void actionPerformed(java.awt.event.ActionEvent evt) {
jButton4ActionPerformed(evt);
}
});
jButton5.setText("Clear");
jButton5.addActionListener(new java.awt.event.ActionListener() {
public void actionPerformed(java.awt.event.ActionEvent evt) {
jButton5ActionPerformed(evt);
}
});
javax.swing.GroupLayout layout = new javax.swing.GroupLayout(this);
this.setLayout(layout);
layout.setHorizontalGroup(
layout.createParallelGroup(javax.swing.GroupLayout.Alignment.LEADING)
.addGroup(layout.createSequentialGroup()
.addGap(66, 66, 66)
.addComponent(jButton1)
.addGap(45, 45, 45)
.addComponent(jButton2)
.addPreferredGap(javax.swing.LayoutStyle.ComponentPlacement.RELATED, 69, Short.MAX_VALUE)
.addComponent(jButton3)
.addGap(27, 27, 27))
.addGroup(layout.createSequentialGroup()
.addGroup(layout.createParallelGroup(javax.swing.GroupLayout.Alignment.LEADING)
.addGroup(layout.createSequentialGroup()
.addGap(39, 39, 39)
.addGroup(layout.createParallelGroup(javax.swing.GroupLayout.Alignment.LEADING)
.addComponent(jLabel1)
.addComponent(jLabel2)
.addComponent(jLabel3))
.addGap(88, 88, 88)
.addGroup(layout.createParallelGroup(javax.swing.GroupLayout.Alignment.LEADING, false)
.addComponent(jTextField1, javax.swing.GroupLayout.DEFAULT_SIZE, 77, Short.MAX_VALUE)
.addComponent(jTextField2)
.addComponent(jTextField3)))
.addGroup(layout.createSequentialGroup()
.addGap(120, 120, 120)
.addComponent(jButton4)
.addGap(45, 45, 45)
.addComponent(jButton5)))
.addContainerGap(javax.swing.GroupLayout.DEFAULT_SIZE, Short.MAX_VALUE))
);
layout.setVerticalGroup(
layout.createParallelGroup(javax.swing.GroupLayout.Alignment.LEADING)
.addGroup(layout.createSequentialGroup()
.addGap(39, 39, 39)
.addGroup(layout.createParallelGroup(javax.swing.GroupLayout.Alignment.BASELINE)
.addComponent(jLabel1)
.addComponent(jTextField1, javax.swing.GroupLayout.PREFERRED_SIZE, javax.swing.GroupLayout.DEFAULT_SIZE, javax.swing.GroupLayout.PREFERRED_SIZE))
.addGap(18, 18, 18)
.addGroup(layout.createParallelGroup(javax.swing.GroupLayout.Alignment.BASELINE)
.addComponent(jLabel2)
.addComponent(jTextField2, javax.swing.GroupLayout.PREFERRED_SIZE, javax.swing.GroupLayout.DEFAULT_SIZE, javax.swing.GroupLayout.PREFERRED_SIZE))
.addGap(18, 18, 18)
.addGroup(layout.createParallelGroup(javax.swing.GroupLayout.Alignment.BASELINE)
.addComponent(jLabel3)
.addComponent(jTextField3, javax.swing.GroupLayout.PREFERRED_SIZE, javax.swing.GroupLayout.DEFAULT_SIZE, javax.swing.GroupLayout.PREFERRED_SIZE))
.addGap(34, 34, 34)
.addGroup(layout.createParallelGroup(javax.swing.GroupLayout.Alignment.BASELINE)
.addComponent(jButton1)
.addComponent(jButton2)
.addComponent(jButton3))
.addGap(18, 18, 18)
.addGroup(layout.createParallelGroup(javax.swing.GroupLayout.Alignment.BASELINE)
.addComponent(jButton4)
.addComponent(jButton5))
.addContainerGap(67, Short.MAX_VALUE))
);
}// </editor-fold>
private void jButton1ActionPerformed(java.awt.event.ActionEvent evt) {
double num1, num2, result;
num1 = Double.parseDouble(jTextField1.getText());
num2 = Double.parseDouble(jTextField2.getText());
result = num1 num2;
jTextField3.setText(String.valueOf(result));
}
private void jButton2ActionPerformed(java.awt.event.ActionEvent evt) {
double num1, num2, result;
num1 = Double.parseDouble(jTextField1.getText());
num2 = Double.parseDouble(jTextField2.getText());
result = num1 - num2;
jTextField3.setText(String.valueOf(result));
}
private void jButton3ActionPerformed(java.awt.event.ActionEvent evt) {
double num1,num2, result;
num1 = Double.parseDouble(jTextField3.getText());
num2 = Double.parseDouble(jTextField2.getText());
result = num1*num2;
jTextField3.setText(String.valueOf(result));
}
private void jButton4ActionPerformed(java.awt.event.ActionEvent evt) {
double num1, num2, result;
num1 = Double.parseDouble(jTextField1.getText());
num2 = Double.parseDouble(jTextField2.getText());
result = num1 / num2;
}
private void jButton5ActionPerformed(java.awt.event.ActionEvent evt) {
jTextField1.setText("");
jTextField2.setText("");
jTextField3.setText("");
}
// Variables declaration - do not modify
private javax.swing.JButton jButton1;
private javax.swing.JButton jButton2;
private javax.swing.JButton jButton3;
private javax.swing.JButton jButton4;
private javax.swing.JButton jButton5;
private javax.swing.JLabel jLabel1;
private javax.swing.JLabel jLabel2;
private javax.swing.JLabel jLabel3;
private javax.swing.JTextField jTextField1;
private javax.swing.JTextField jTextField2;
private javax.swing.JTextField jTextField3;
// End of variables declaration
}
解決方法: JPanel不是沒有像JFrame這樣的頂級容器的可運(yùn)行類,你需要一個main方法.您應(yīng)該創(chuàng)建一個JFrame表單,而不是創(chuàng)建JPanel表單,該表單具有為您自動生成的主方法.看起來您正在使用Netbeans GUI Builder.只需打開一個新的JFrame表單.您只需將JPanel表單添加到JFrame表單即可.
使用NetBeans設(shè)計視圖,您只需將JPanel表單拖放到JFrame表單,如here所示
另外,要明確指定項目的Main類,請參閱here 來源：https://www./content-1-408001.html
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