JTextFields和我的学校项目

Question

在我的化学课上，老师告诉我可以通过制作一些与化学相关的课程来获得额外的学分。我觉得这是个好主意，因为我毕竟是在学习计算机科学。到目前为止，这是我的代码，但我无法让它显示我想要的字符串，即使在我按下回车键之后。任何帮助都会很棒。谢谢

import java.awt.Color;
import java.awt.Font;
import java.awt.Graphics;
import java.awt.event.KeyEvent;
import java.awt.event.KeyListener;
import javax.swing.*;
    public class window extends JPanel implements KeyListener {
        private static final long serialVersionUID = 1L;
        private JTextField textBox;
        private String textInput;
        public window() {
        textInput = "";
        textBox = new JTextField("Enter symbol here:", 30);
        this.add(textBox);
    }
    public void paint(Graphics g) {
        super.paint(g);
        g.setColor(Color.CYAN);
        g.setFont(new Font("", Font.BOLD, 20));
        g.drawString("Enter element symbol in text box above.", 110, 50);
        g.drawString(textInput, 100, 100);
    }
    public void keyPressed(KeyEvent e) {
        int code = e.getKeyCode();
        if (code == KeyEvent.VK_ENTER) {
            textInput = textBox.getText();
        }
        repaint();
    }
    public void keyReleased(KeyEvent e) {
    }
    public void keyTyped(KeyEvent e) {
    }
}

import java.awt.Color;
import javax.swing.JFrame;
    public class elementRunner {
        public static void main(String[] args) {
            window panel = new window();
        JFrame frame = new JFrame("Element project ~ By: Harsh Patel");
        frame.setBounds(100, 100, 600, 600);
        frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
        frame.setResizable(false);
        panel.setBackground(Color.RED);
        frame.setVisible(true);
        frame.addKeyListener(panel);
        frame.add(panel);
    }
}

Answer 1

问题是将侦听器设置为JPanel，如果将其设置为JTextField，则可以正常工作。不过，我附上了下面的代码，也许JLabels会有所帮助。我的意思是，它更容易，更结构化等等。但你必须学习布局是如何工作的。不管怎样，在我看来就是这样：

ElementRunner.java （大写Element）

public class ElementRunner {
    public static void main(String[] args) {
        MyWindow panel = new MyWindow();
        panel.setBackground(Color.RED);
        JFrame frame = new JFrame("Element project ~ By: Harsh Patel");
        frame.setBounds(100, 100, 600, 600);
        frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
        frame.setResizable(false);
        frame.add(panel);
        frame.setVisible(true);
    }
}

MyWindow.java（Window太通用了，这样我们就知道它是你的，像Element一样大写）

public class MyWindow extends JPanel implements KeyListener {
    private static final long serialVersionUID = 1L;
    private JTextField textBox;
    private String textInput;
    public MyWindow() {
        textInput = "";
        textBox = new JTextField("Enter symbol here:", 30);
        textBox.addKeyListener(this); // This line adds the listener to the TextField
        this.add(textBox);
    }
    public void paint(Graphics g) {
        super.paint(g);
        g.setColor(Color.CYAN);
        g.drawString("Enter element symbol in text box above.", 110, 50);
        g.drawString(textInput, 100, 100);
    }
    public void keyPressed(KeyEvent e) {
        int code = e.getKeyCode();
        if (code == KeyEvent.VK_ENTER) {
            textInput = textBox.getText();
        }
        repaint();
    }
    public void keyReleased(KeyEvent e) { }
    public void keyTyped(KeyEvent e) { }
}