Question

在下面的代码中，我得到了一个NullPointerException：

Exception in thread "AWT-EventQueue-0" java.lang.NullPointerException

timer.setInitialDelay((int) delay);

我尝试添加

//timer = new Timer(0, null);
long delay = dates.getTime() - System.currentTimeMillis();
  timer = new Timer(0, null);
  new TimerStart();
  if (delay >= 0) {
   timer.setInitialDelay((int) delay);
   timer.restart();
  }

为了避免异常，它可以工作，但不会触发定时器吗？

使用此示例，它也适用于计时器触发器，但如何在上面的代码中进行更正：

import java.awt.BorderLayout;
import java.awt.event.ActionEvent;
import javax.swing.JFrame;
import javax.swing.JLabel;
import javax.swing.JPanel;
import javax.swing.JSpinner;
import javax.swing.SpinnerDateModel;
import javax.swing.SpinnerModel;
import java.util.Date;
import javax.swing.Timer;
import javax.swing.event.ChangeEvent;
import javax.swing.event.ChangeListener;

public class SpinnerTest {

 Timer timer;
 Date date;
 public static void main(String args[]) {
   new SpinnerTest().startApp();
 }

 private void startApp() {
 JFrame frame = new JFrame("JSpinner Sample");
 frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);

 date = new Date();
 SpinnerModel model1 = new SpinnerDateModel(date,null,null,0);
 JSpinner spinner1 = new JSpinner(model1);

 spinner1.addChangeListener(new CalendarListener());
 spinner1.setEditor(new JSpinner.DateEditor(spinner1, "HH:mm dd-MM-yyyy"));

 JLabel label1 = new JLabel("Times/Dates");
 JPanel panel1 = new JPanel(new BorderLayout());
 JPanel panel2 = new JPanel(new BorderLayout());

 panel2.add(label1, BorderLayout.WEST);
 panel1.add(spinner1, BorderLayout.CENTER);

 frame.add(panel1, BorderLayout.CENTER);
 frame.add(panel2, BorderLayout.WEST);

 frame.setSize(200, 90);
 frame.setVisible(true);
}
  private class CalendarListener implements ChangeListener {
   @Override
   public void stateChanged(ChangeEvent e)  {
    JSpinner jSpinner = (JSpinner) e.getSource();
    date = (Date) jSpinner.getValue() ;
    long delay = date.getTime() - System.currentTimeMillis();
    //System.out.println(delay);
    timerStart();
    if (delay > 0) {
    timer.setInitialDelay((int) delay);
    timer.restart();
   }
  }   
 }
 private void timerStart() {
     this.timer = new Timer(Integer.MAX_VALUE, (ActionEvent evt) -> {
     System.out.println("okey");
    });}
   }

使用JSpinner和Timer的例外？

0 个答案: