简单的JFrame程序但看不到JTextfield

我正试着自己学习Swing。 我正在玩玩具程序，要求用户输入他们的名字。 我将JLabel和JTextfield放入JPanel，用户可以在其中输入名称并提交。 然而，我的JTextfield被压扁并且看不见，我无法让它显示（我试过“setSize”无济于事）。

这是我的代码：

import javax.swing.JFrame; import javax.swing.JLabel; import javax.swing.JPanel; import javax.swing.JTextField; public class NamePrompt extends JFrame{ private static final long serialVersionUID = 1L; String name; public NamePrompt(){ setLayout(new BorderLayout()); JLabel enterYourName = new JLabel("Enter Your Name Here:"); JTextField textBoxToEnterName = new JTextField(); textBoxToEnterName.setSize(40, 10); JPanel panelTop = new JPanel(); panelTop.add(enterYourName); panelTop.add(textBoxToEnterName); JButton submit = new JButton("Submit"); submit.addActionListener(new SubmitButton()); JPanel panelBottom = new JPanel(); panelBottom.add(submit); //Add panelTop to JFrame add(panelTop, BorderLayout.NORTH); add(panelBottom, BorderLayout.SOUTH); //JFrame set-up setTitle("Name Prompt Program"); setSize(300, 150); setLocationRelativeTo(null); } public static void main(String[] args) { NamePrompt promptForName = new NamePrompt(); promptForName.setVisible(true); } 

Answer 1

 JTextField textBoxToEnterName = new JTextField(20); 

有关说明，请参阅new JTextField(columns) 。 例如

 import java.awt.BorderLayout; import javax.swing.*; public class NamePrompt extends JFrame{ private static final long serialVersionUID = 1L; String name; public NamePrompt(){ setLayout(new BorderLayout()); JLabel enterYourName = new JLabel("Enter Your Name Here:"); JTextField textBoxToEnterName = new JTextField(21); //textBoxToEnterName.setSize(40, 10); JPanel panelTop = new JPanel(); panelTop.add(enterYourName); panelTop.add(textBoxToEnterName); JButton submit = new JButton("Submit"); //submit.addActionListener(new SubmitButton()); JPanel panelBottom = new JPanel(); panelBottom.add(submit); //Add panelTop to JFrame add(panelTop, BorderLayout.NORTH); add(panelBottom, BorderLayout.SOUTH); //JFrame set-up setTitle("Name Prompt Program"); //setSize(300, 150); pack(); setLocationRelativeTo(null); } public static void main(String[] args) { NamePrompt promptForName = new NamePrompt(); promptForName.setVisible(true); } }