当我单击“添加”按钮时，我想添加文本字段。 但它不起作用。 帮我

Question

this is my code. I want to let the user add a new text field as they want, but it only can add one text field. will loop for Participant gonna work?

 import java.awt.EventQueue; import javax.swing.JFrame; import javax.swing.JLabel; import java.awt.Font; import javax.swing.JTextField; import javax.swing.JButton; import java.awt.event.ActionListener; import java.awt.event.ActionEvent; import javax.swing.JTextArea; import java.awt.Color; import java.awt.SystemColor; public class General { private JFrame frame; private JTextField textFirst; /** * Launch the application. */ public static void main(String[] args) { EventQueue.invokeLater(new Runnable() { public void run() { try { General window = new General(); window.frame.setVisible(true); } catch (Exception e) { e.printStackTrace(); } } }); } /** * Create the application. */ public General() { initialize(); } /** * Initialize the contents of the frame. */ private void initialize() { frame = new JFrame(); frame.setBounds(100, 100, 450, 300); frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE); frame.getContentPane().setLayout(null); JLabel lblInsertParticipantsTerm = new JLabel("Insert Participants Term:"); lblInsertParticipantsTerm.setFont(new Font("Tahoma", Font.BOLD, 12)); lblInsertParticipantsTerm.setBounds(34, 32, 169, 14); frame.getContentPane().add(lblInsertParticipantsTerm); textFirst = new JTextField(); textFirst.setBounds(23, 52, 180, 20); frame.getContentPane().add(textFirst); textFirst.setColumns(10); JButton button = new JButton("ADD"); button.addActionListener(new ActionListener() { public void actionPerformed(ActionEvent arg0) { JTextField newTextField = new JTextField(20); frame.getContentPane().add(newTextField); frame.validate(); frame.repaint(); } }); button.setBounds(205, 51, 53, 23); frame.getContentPane().add(button); JTextArea textArea = new JTextArea(); textArea.setBackground(SystemColor.control); textArea.setBounds(23, 52, 180, 199); frame.getContentPane().add(textArea); } }

Answer 1

You need to have a layout manager. Do the following:

frame.getContentPane().setLayout(new FlowLayout());