0
我已经创建了一个GUI并复制了生成代码，仔细修改了什么是必要的，以便添加到类中并添加了所有必需的导入等，但是当我构建项目时，它给了我这个错误，我我无法弄清楚Java布局调试错误
run: Exception in thread "main" java.lang.NullPointerException at question3_test.Triangle.<init>(Triangle.java:35) at question3_test.Triangle.main(Triangle.java:142) Java Result: 1 BUILD SUCCESSFUL (total time: 3 seconds)
这是我复制过来（如果更好地理解）
package question3_test;
import java.awt.*;
import javax.swing.*;
public class Triangle extends JFrame
{
private JButton jButton1;
private JLabel jLabel2;
private JLabel jLabel3;
private JPanel jPanel1;
private JLabel result_lbl;
private JLabel side1_lbl;
private JTextField side1_tf;
private JTextField side2_tf;
private JTextField side3_tf;
private Label title_lbl;
private void initComponents()
{
}
public Triangle()
{
jPanel1.setMaximumSize(new Dimension(200, 200));
title_lbl.setFont(new Font("Arial", 1, 18)); // NOI18N
title_lbl.setText("AREA OF TRIANGLE");
side1_lbl.setFont(new Font("Tahoma", 1, 11)); // NOI18N
side1_lbl.setText("Side 1:");
jLabel2.setFont(new Font("Tahoma", 1, 11)); // NOI18N
jLabel2.setText("Side 2:");
jLabel3.setFont(new java.awt.Font("Tahoma", 1, 11)); // NOI18N
jLabel3.setText("Side 3:");
side1_tf.setMinimumSize(new java.awt.Dimension(60, 20));
side2_tf.setMinimumSize(new java.awt.Dimension(60, 20));
side3_tf.setMinimumSize(new java.awt.Dimension(60, 20));
jButton1.setFont(new java.awt.Font("Tahoma", 1, 11)); // NOI18N
jButton1.setText("Calculate Area");
jButton1.setBorder(null);
result_lbl.setText("jLabel4");
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()
.addContainerGap(25, Short.MAX_VALUE)
.addGroup(jPanel1Layout.createParallelGroup(javax.swing.GroupLayout.Alignment.LEADING)
.addGroup(jPanel1Layout.createSequentialGroup()
.addGap(33, 33, 33)
.addGroup(jPanel1Layout.createParallelGroup(javax.swing.GroupLayout.Alignment.LEADING)
.addGroup(jPanel1Layout.createSequentialGroup()
.addComponent(side1_lbl)
.addPreferredGap(javax.swing.LayoutStyle.ComponentPlacement.UNRELATED)
.addComponent(side1_tf, javax.swing.GroupLayout.PREFERRED_SIZE, 60, javax.swing.GroupLayout.PREFERRED_SIZE))
.addGroup(jPanel1Layout.createSequentialGroup()
.addGroup(jPanel1Layout.createParallelGroup(javax.swing.GroupLayout.Alignment.LEADING)
.addGroup(javax.swing.GroupLayout.Alignment.TRAILING, jPanel1Layout.createSequentialGroup()
.addComponent(jLabel2)
.addPreferredGap(javax.swing.LayoutStyle.ComponentPlacement.UNRELATED))
.addGroup(jPanel1Layout.createSequentialGroup()
.addComponent(jLabel3)
.addGap(10, 10, 10)))
.addGroup(jPanel1Layout.createParallelGroup(javax.swing.GroupLayout.Alignment.TRAILING, false)
.addComponent(side3_tf, javax.swing.GroupLayout.DEFAULT_SIZE, javax.swing.GroupLayout.DEFAULT_SIZE, Short.MAX_VALUE)
.addComponent(side2_tf, javax.swing.GroupLayout.PREFERRED_SIZE, 60, javax.swing.GroupLayout.PREFERRED_SIZE)))))
.addGroup(jPanel1Layout.createSequentialGroup()
.addGap(60, 60, 60)
.addComponent(result_lbl))
.addComponent(title_lbl, javax.swing.GroupLayout.PREFERRED_SIZE, javax.swing.GroupLayout.DEFAULT_SIZE, javax.swing.GroupLayout.PREFERRED_SIZE)
.addGroup(jPanel1Layout.createSequentialGroup()
.addGap(17, 17, 17)
.addComponent(jButton1, javax.swing.GroupLayout.PREFERRED_SIZE, 132, javax.swing.GroupLayout.PREFERRED_SIZE)))
.addGap(30, 30, 30))
);
jPanel1Layout.setVerticalGroup(
jPanel1Layout.createParallelGroup(javax.swing.GroupLayout.Alignment.LEADING)
.addGroup(jPanel1Layout.createSequentialGroup()
.addComponent(title_lbl, javax.swing.GroupLayout.PREFERRED_SIZE, 44, javax.swing.GroupLayout.PREFERRED_SIZE)
.addPreferredGap(javax.swing.LayoutStyle.ComponentPlacement.RELATED)
.addGroup(jPanel1Layout.createParallelGroup(javax.swing.GroupLayout.Alignment.BASELINE)
.addComponent(side1_lbl)
.addComponent(side1_tf, javax.swing.GroupLayout.PREFERRED_SIZE, javax.swing.GroupLayout.DEFAULT_SIZE, javax.swing.GroupLayout.PREFERRED_SIZE))
.addGap(18, 18, 18) .addGroup(jPanel1Layout.createParallelGroup(javax.swing.GroupLayout.Alignment.BASELINE)
.addComponent(jLabel2)
.addComponent(side2_tf, javax.swing.GroupLayout.PREFERRED_SIZE, javax.swing.GroupLayout.DEFAULT_SIZE, javax.swing.GroupLayout.PREFERRED_SIZE))
.addGap(18, 18, 18)
.addGroup(jPanel1Layout.createParallelGroup(javax.swing.GroupLayout.Alignment.BASELINE)
.addComponent(jLabel3)
.addComponent(side3_tf, javax.swing.GroupLayout.PREFERRED_SIZE, javax.swing.GroupLayout.DEFAULT_SIZE, javax.swing.GroupLayout.PREFERRED_SIZE))
.addGap(18, 18, 18)
.addComponent(jButton1, javax.swing.GroupLayout.PREFERRED_SIZE, 31, javax.swing.GroupLayout.PREFERRED_SIZE)
.addGap(18, 18, 18)
.addComponent(result_lbl)
.addGap(0, 21, Short.MAX_VALUE))
);
title_lbl.getAccessibleContext().setAccessibleName("Area of Triangle");
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(37, Short.MAX_VALUE)
.addComponent(jPanel1, javax.swing.GroupLayout.PREFERRED_SIZE, javax.swing.GroupLayout.DEFAULT_SIZE, javax.swing.GroupLayout.PREFERRED_SIZE)
.addGap(18, 18, 18))
);
layout.setVerticalGroup(
layout.createParallelGroup(javax.swing.GroupLayout.Alignment.LEADING)
.addGroup(layout.createSequentialGroup()
.addContainerGap()
.addComponent(jPanel1, javax.swing.GroupLayout.PREFERRED_SIZE, javax.swing.GroupLayout.DEFAULT_SIZE, javax.swing.GroupLayout.PREFERRED_SIZE)
.addContainerGap(25, Short.MAX_VALUE))
);
}
public static void main(String args [])
{
Triangle mytri = new Triangle();
mytri.setVisible(true);
}
}
随着你注定的变量名。更糟的是，在gui应用程序中这样做。 – UmNyobe
他们怎么了？ – noobprogrammer
他们不明确。代码将非常难以阅读（即使对你而言）。 – UmNyobe