我正在尝试为我构建的随机名称生成器构建一个GUI，目前我正试图在按下按钮时打印出名称。
然而，我获得的名称列表不是“[]”。我对GUI编程知之甚少，所以我不确定这里出了什么问题。
import java.io.IOException;
import java.nio.file.Files;
import java.nio.file.Paths;
import java.util.ArrayList;
import java.util.List;
import java.util.Random;
import java.util.Scanner;
import java.nio.file.*;
import java.util.*;
public class Applet1 extends javax.swing.JApplet {
public static List<String> list = new ArrayList<String>();
public static void init(String args[])throws IOException{
List<String> prefix = Files.readAllLines(Paths.get("prefix.txt"));
List<String> suffix = Files.readAllLines(Paths.get("suffix.txt"));
Random randomizer = new Random();
String prefix2 = prefix.get(randomizer.nextInt(prefix.size()));
String suffix2 = suffix.get(randomizer.nextInt(suffix.size()));
Random ran = new Random();
int C = ran.nextInt(5);
for(int A=0;A <= 5;A++){
if( C == 0 )
list.add(prefix2 + " ");
else if( C>0 && C<3 )
list.add(prefix2 + suffix2+ " ");
else if( C>2 && C<6 )
list.add(prefix2 + " " + prefix2 + suffix2+ " ");}}
public void init() {
/* 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(Applet1.class.getName()).log(java.util.logging.Level.SEVERE, null, ex);
} catch (InstantiationException ex) {
java.util.logging.Logger.getLogger(Applet1.class.getName()).log(java.util.logging.Level.SEVERE, null, ex);
} catch (IllegalAccessException ex) {
java.util.logging.Logger.getLogger(Applet1.class.getName()).log(java.util.logging.Level.SEVERE, null, ex);
} catch (javax.swing.UnsupportedLookAndFeelException ex) {
java.util.logging.Logger.getLogger(Applet1.class.getName()).log(java.util.logging.Level.SEVERE, null, ex);
}
//</editor-fold>
/* Create and display the applet */
try {
java.awt.EventQueue.invokeAndWait(new Runnable() {
public void run() {
initComponents();
}
});
} catch (Exception ex) {
ex.printStackTrace();
}
}
/**
* This method is called from within the init() method 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() {
jComboBox1 = new javax.swing.JComboBox<>();
jButton1 = new javax.swing.JButton();
jLabel1 = new javax.swing.JLabel();
jTextField1 = new javax.swing.JTextField();
setMinimumSize(new java.awt.Dimension(498, 517));
jComboBox1.setModel(new javax.swing.DefaultComboBoxModel<>(new String[] { "1", "5", "10", "15" }));
jButton1.setText("Press");
jButton1.addActionListener(new java.awt.event.ActionListener() {
public void actionPerformed(java.awt.event.ActionEvent evt) {
jButton1ActionPerformed(evt);
}
});
jLabel1.setFont(new java.awt.Font("Tahoma", 0, 14)); // NOI18N
jLabel1.setText("Select number of names and press button to Generate");
javax.swing.GroupLayout layout = new javax.swing.GroupLayout(getContentPane());
getContentPane().setLayout(layout);
layout.setHorizontalGroup(
layout.createParallelGroup(javax.swing.GroupLayout.Alignment.LEADING)
.addGroup(layout.createSequentialGroup()
.addGap(18, 18, 18)
.addGroup(layout.createParallelGroup(javax.swing.GroupLayout.Alignment.LEADING)
.addComponent(jLabel1, javax.swing.GroupLayout.PREFERRED_SIZE, 345, javax.swing.GroupLayout.PREFERRED_SIZE)
.addComponent(jTextField1, javax.swing.GroupLayout.PREFERRED_SIZE, 359, javax.swing.GroupLayout.PREFERRED_SIZE)
.addGroup(layout.createSequentialGroup()
.addComponent(jButton1)
.addGap(18, 18, 18)
.addComponent(jComboBox1, javax.swing.GroupLayout.PREFERRED_SIZE, 80, javax.swing.GroupLayout.PREFERRED_SIZE)))
.addContainerGap(121, Short.MAX_VALUE))
);
layout.setVerticalGroup(
layout.createParallelGroup(javax.swing.GroupLayout.Alignment.LEADING)
.addGroup(layout.createSequentialGroup()
.addContainerGap()
.addComponent(jLabel1, javax.swing.GroupLayout.PREFERRED_SIZE, 32, javax.swing.GroupLayout.PREFERRED_SIZE)
.addPreferredGap(javax.swing.LayoutStyle.ComponentPlacement.UNRELATED)
.addGroup(layout.createParallelGroup(javax.swing.GroupLayout.Alignment.LEADING)
.addComponent(jButton1)
.addComponent(jComboBox1, javax.swing.GroupLayout.PREFERRED_SIZE, 21, javax.swing.GroupLayout.PREFERRED_SIZE))
.addGap(18, 18, 18)
.addComponent(jTextField1, javax.swing.GroupLayout.PREFERRED_SIZE, 389, javax.swing.GroupLayout.PREFERRED_SIZE)
.addContainerGap(33, Short.MAX_VALUE))
);
}// </editor-fold>
private void jButton1ActionPerformed(java.awt.event.ActionEvent evt) {
jTextField1.setText(list.toString());
}
// Variables declaration - do not modify
private javax.swing.JButton jButton1;
private javax.swing.JComboBox<String> jComboBox1;
private javax.swing.JLabel jLabel1;
private javax.swing.JTextField jTextField1;
// End of variables declaration
}
据我所知，我已经在某处破坏了代码，或者TextField无法处理String Arrays。
答案 0 :(得分：3)
您的问题与GUI或Swing代码无关，而与故障for循环有关。它永远不会循环，因为你的情况是倒退的：
for(int A=0;A >= 5;A++){
由于A变量开始为0，它永远不会满足A >= 5的for循环布尔条件，因此循环永远不会“循环”，并且列表保持为空 - 这就是你看到了。
一种解决方案是更改循环以使其正常工作，也许您想要：
for(int A = 0; A <= 5; A++) { // this loops 6 times (not 5)
请查看：How to Debug Small Programs
此外，您的课程是一个小程序，但您已经为它提供了一个主要方法 - 从不在applet中运行的方法。该代码不应该采用init()方法吗？
答案 1 :(得分：3)
永远不会调用此方法：
public static void init(String args[])throws IOException{
因此，list仍为空。
其他提示/注释/问题：
小程序中设置了小程序的大小，因此不应在代码中调用任何大小（最小值，大小或最大值）的设置。
setMinimumSize(new java.awt.Dimension(498, 517));
为什么要编写applet代码？如果是教师指定的，请将其转介至Why CS teachers should stop teaching Java applets。
JTextArea）。