我试图编写一个小小的Java程序，该程序应该用作计时器。
问题是（可能是）我需要使用Thread.sleep()，并抛出InterruptedException。因此，如果我启动程序，则可以每分钟输入秒钟，但是按“确定”时，什么也不会发生（它也不会在终端中显示任何警告或错误）。
这里是代码：
import javax.swing.*;
import java.awt.*;
import java.awt.event.ActionEvent;
import java.awt.event.ActionListener;
import java.text.NumberFormat;
import javax.swing.text.NumberFormatter;
import static javax.swing.WindowConstants.EXIT_ON_CLOSE;
public class Timer {
public static void main(String[] args) throws InterruptedException {
SwingUtilities.invokeLater(Timer::new);
}
private JButton button;
private JTextField minutes;
private JTextField seconds;
Timer() {
JFrame frame = new JFrame();
frame.setSize(300, 200);
frame.setDefaultCloseOperation(EXIT_ON_CLOSE);
JPanel panel = new JPanel(new BorderLayout());
JPanel subpanel1 = new JPanel(new GridLayout(1, 2));
/*
* The following lines ensure that the user can
* only enter numbers.
*/
NumberFormat format = NumberFormat.getInstance();
NumberFormatter formatter = new NumberFormatter(format);
formatter.setValueClass(Integer.class);
formatter.setMinimum(0);
formatter.setMaximum(Integer.MAX_VALUE);
formatter.setAllowsInvalid(false);
formatter.setCommitsOnValidEdit(true);
minutes = new JFormattedTextField(formatter);
seconds = new JFormattedTextField(formatter);
minutes.setText("0");
seconds.setText("0");
JPanel subpanel2 = new JPanel();
/*
* When the user presses the OK-button, the program will
* start to count down.
*/
button = new JButton("OK");
button.addActionListener(new ActionListener() {
@Override
public void actionPerformed(ActionEvent actionEvent) {
try {
timer();
}
catch(InterruptedException e) {
}
}
});
JButton button2 = new JButton("Reset");
button2.addActionListener(new ActionListener() {
@Override
public void actionPerformed(ActionEvent actionEvent) {
minutes.setText("0");
seconds.setText("0");
button.setEnabled(true);
}
});
subpanel1.add(minutes);
subpanel1.add(seconds);
subpanel2.add(button);
subpanel2.add(button2);
panel.add(subpanel1, BorderLayout.CENTER);
panel.add(subpanel2, BorderLayout.PAGE_END);
frame.add(panel);
frame.setVisible(true);
}
//Method for the timer
void timer() throws InterruptedException {
int min = Integer.valueOf(minutes.getText());
int sec = Integer.valueOf(seconds.getText());
button.setEnabled(false);
while(min > 0 || sec > 0) {
Thread.sleep(1000);
if(sec >= 1) {
sec = sec - 1;
seconds.setText(String.valueOf(sec));
}
else if(sec == 0 || min > 0) {
sec = 59;
min = min - 1;
seconds.setText(String.valueOf(sec));
minutes.setText(String.valueOf(min));
}
}
}
}
我该怎么做才能使其正常工作？
我知道将Thread.sleep()替换为以下内容：
Timer timer = new Timer(delay, taskPerformer);
timer.setRepeats( false );
timer.start();
现在发生错误：构造函数无法应用于给定的类型（它不需要参数）。我做错了什么？ （已定义变量delay和taskPerformer，并且我没有导入java.util.Timer）
以下mre显示了如何使用javax.swing.Timer获得所需的倒数：
import static javax.swing.WindowConstants.EXIT_ON_CLOSE;
import java.awt.BorderLayout;
import java.awt.GridLayout;
import java.text.NumberFormat;
import javax.swing.JButton;
import javax.swing.JFormattedTextField;
import javax.swing.JFrame;
import javax.swing.JPanel;
import javax.swing.JTextField;
import javax.swing.SwingUtilities;
import javax.swing.Timer;
import javax.swing.text.NumberFormatter;
public class MyTimer {
public static void main(String[] args) throws InterruptedException {
SwingUtilities.invokeLater(MyTimer::new);
}
private final JButton startButton, resetButton;
private final JTextField minutes;
private final JTextField seconds;
private static final int SECOND = 1000;
private Timer timer;
MyTimer() {
JFrame frame = new JFrame();
//frame.setSize(300, 200);
frame.setDefaultCloseOperation(EXIT_ON_CLOSE);
/*
* The following lines ensure that the user can
* only enter numbers.
*/
NumberFormat format = NumberFormat.getInstance();
NumberFormatter formatter = new NumberFormatter(format);
formatter.setValueClass(Integer.class);
formatter.setMinimum(0);
formatter.setMaximum(Integer.MAX_VALUE);
formatter.setAllowsInvalid(false);
formatter.setCommitsOnValidEdit(true);
minutes = new JFormattedTextField(formatter);
seconds = new JFormattedTextField(formatter);
minutes.setText("0");
seconds.setText("0");
/*
* When the user presses the OK-button, the program will
* start to count down.
*/
startButton = new JButton("OK");
startButton.addActionListener(actionEvent -> {
timer();
});
resetButton = new JButton("Reset");
resetButton.setEnabled(false);
resetButton.addActionListener(actionEvent -> {
reset();
});
JPanel subpanel1 = new JPanel(new GridLayout(1, 2));
subpanel1.add(minutes);
subpanel1.add(seconds);
JPanel subpanel2 = new JPanel();
subpanel2.add(startButton);
subpanel2.add(resetButton);
JPanel panel = new JPanel(new BorderLayout());
panel.add(subpanel1, BorderLayout.CENTER);
panel.add(subpanel2, BorderLayout.PAGE_END);
frame.add(panel);
frame.pack();
frame.setVisible(true);
}
void timer() {
startButton.setEnabled(false);
timer = new Timer(SECOND, e->{
final int min = Integer.valueOf(minutes.getText());
final int sec = Integer.valueOf(seconds.getText());
if(sec == 0 && min == 0){
reset();
}else if(sec >= 1) {
seconds.setText(String.valueOf(sec-1));
}
else if(sec == 0 || min > 0) {
seconds.setText(String.valueOf(59));
minutes.setText(String.valueOf(min-1));
}
});
timer.setRepeats(true);
timer.start();
resetButton.setEnabled(true);
}
private void reset() {
if(timer != null) {
timer.stop();
}
minutes.setText("0");
seconds.setText("0");
startButton.setEnabled(true);
}
}
由于您只需要计时器来显示小时，您可以简单地创建一个新线程来处理该时间，而让主线程来处理其他内容，例如用户IO。