好的，所以我是 Java 编程的新手，我想制作一个简单的 JAVA GUI 应用程序，您首先输入秒数，然后在该秒数内尽可能多次单击按钮（例如单击速度测试概念）。它远未完成，现在我正在实施，以便我可以为文本字段添加一个占位符以向用户解释，但焦点动作侦听器不起作用。
import javax.swing.*;
import java.awt.*;
import java.awt.event.ActionEvent;
import java.awt.event.ActionListener;
import java.awt.event.FocusEvent;
import java.awt.event.FocusListener;
import java.time.LocalTime;
import java.util.*;
public class Main implements ActionListener, FocusListener {
private JPanel panel;
private JPanel initPanel;
private JFrame frame;
private JButton button;
private JButton newButton;
private JLabel label;
private JLabel newLabel;
private JTextField textInput;
private LocalTime time;
private ImageIcon img;
private int count = 0;
private Scanner input = new Scanner(System.in);
public static void constructor() {
Main app = new Main();
app.panel = new JPanel();
app.frame = new JFrame();
app.label = new JLabel("Number of clicks: 0");
app.img = new ImageIcon("E:\\Descarcari Chrome\\mouse.png");
app.time = LocalTime.now();
app.panel.setBorder(BorderFactory.createEmptyBorder(20, 40, 10, 40));
app.panel.setLayout(new GridLayout(0, 1));
app.button = new JButton("Click me!");
app.button.setFocusPainted(false);
app.button.setFont(new Font("Arial", Font.BOLD, 40));
app.button.addActionListener(app);
app.panel.add(app.button);
app.panel.add(app.label);
app.frame.add(app.panel, BorderLayout.CENTER);
app.frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
app.frame.setTitle("Click Speed Test");
app.frame.setIconImage(app.img.getImage());
app.frame.pack();
app.frame.setVisible(true);
app.frame.setResizable(false);
}
public static void chooseTime() {
Main app = new Main();
app.initPanel = new JPanel();
app.newButton = new JButton("Submit!");
app.textInput = new JTextField("Number of seconds for the test");
app.frame = new JFrame();
app.newButton.setFocusPainted(false);
app.newButton.setFont(new Font("Arial", Font.BOLD, 40));
app.newButton.addActionListener(app);
app.textInput.setForeground(Color.GRAY);
app.initPanel.setBorder(BorderFactory.createEmptyBorder(20, 40, 10, 40));
app.initPanel.setLayout(new GridLayout(0, 1));
app.initPanel.add(app.newButton);
app.initPanel.add(app.textInput);
app.textInput.addActionListener(app);
app.frame.add(app.initPanel, BorderLayout.CENTER);
app.frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
app.frame.setTitle("Click Speed Test");
app.frame.pack();
app.frame.setVisible(true);
app.frame.setResizable(false);
}
public static void main(String[] args) {
chooseTime();
}
@Override
public void actionPerformed(ActionEvent e) {
if (e.getSource() == button) {
count++;
label.setText("Number of clicks: " + count);
button.setText("");
} else if (textInput.getText().isEmpty() == false){
frame.getContentPane().removeAll();
frame.repaint();
frame.setVisible(false);
constructor();
}else {
JLabel wrong = new JLabel("Input cannot be null");
initPanel.add(wrong);
chooseTime();
}
}
@Override
public void focusGained(FocusEvent e) {
System.out.println("FOCUS");
if(textInput.getText().equals("Number of seconds for the test")) {
textInput.setText("");
textInput.setForeground(Color.BLACK);
}
}
@Override
public void focusLost(FocusEvent e) {
System.out.println("LOST FOCUS");
if(textInput.getText().isEmpty()) {
textInput.setForeground(Color.GRAY);
textInput.setText("Number of seconds for the test");
}
}
}
让我解释一下我在做什么：
chooseTime方法是首先运行的方法，它只是创建一个按钮，现在只是关闭当前帧并运行并运行该constructor方法，该方法只会增加每次按下按钮的点击次数。