Problems using SimpleDateFormat

问题

Apparently, I'm missing something fundamental. I'm having a problem with formatting the value of a jspinner. I've tried a couple different ways and keep receiving an error, didn't keep track of them, other than it has to do with how I'm trying to grab the value from jspinner.

Here is the spinner code:

//setup date format for both spinners
SimpleDateFormat datePattern = new SimpleDateFormat("MM/dd/yyyy");
JSpinner dateFrom = new JSpinner(new SpinnerDateModel());
dateFrom.setEditor(new JSpinner.DateEditor(dateFrom, datePattern.toPattern()));
JPanel dateFromPanel = new JPanel(new GridLayout());
dateFromPanel.add(dateFrom);
dateFromPanel.setBorder(new TitledBorder("Date - From"));

Here is how I'm currently trying to get the format:

SimpleDateFormat sdfSource = new SimpleDateFormat("MM/dd/yyyy");
Date from = sdfSource.parse(dateFrom.getValue().toString());
SimpleDateFormat sdfDestination = new SimpleDateFormat("MM/dd/yyyy");           
String dosFrom = sdfDestination.format(from);

Current error: Exception in thread "main" java.text.ParseException: Unparseable date: "Mon Oct 23 00:00:00 EDT 2006"

回答1:

I suspect the problem is this:

dateFrom.getValue().toString()

I suspect dateFrom.getValue() is just returning a Date - which of course doesn't have any associated format. Instead of parsing that, you should just cast it:

Date from = (Date) dateFrom.getValue();

I could be wrong, of course... but that would be my first thought.

回答2:

you have to read tutorial about JSpinners and to set SpinnerDateModel for JSpinner instace, then you couldn't needed to solve parsing Date instance from JSpinner

simple example for usage of SpinnerDateModel

import java.awt.*;
import java.text.SimpleDateFormat;
import java.util.*;
import javax.swing.*;
import javax.swing.event.*;

public class TimeZoneSpinners {

    private final String[] zones = {"Asia/Tokyo", "Asia/Hong_Kong",
        "Asia/Calcutta", "Europe/Paris", "Europe/London",
        "America/New_York", "America/Los_Angeles"
    };
    private final JLabel[] labels = new JLabel[zones.length];
    private final SimpleDateFormat[] formats = new SimpleDateFormat[zones.length];
    private JSpinner spinner;
    private SpinnerDateModel model;
    private SimpleDateFormat format;
    private JPanel panel;
    private JFrame frame = new JFrame();

    public void makeUI() {
        Calendar cal = Calendar.getInstance();
        Date date = cal.getTime();
        model = new SpinnerDateModel();
        model.setValue(date);
        spinner = new JSpinner(model);
        spinner.addChangeListener(new ChangeListener() {

            @Override
            public void stateChanged(ChangeEvent e) {
                Date date = (Date) ((JSpinner) e.getSource()).getValue();
                for (int i = 0; i < labels.length; i++) {
                    labels[i].setText(formats[i].format(date));
                }
            }
        });
        format = ((JSpinner.DateEditor) spinner.getEditor()).getFormat();
        format.setTimeZone(TimeZone.getTimeZone(zones[0]));
        format.applyPattern("yyyy-MM-dd HH:mm:ss");
        panel = new JPanel(new GridLayout(zones.length, 2, 10, 10));
        for (int i = 0; i < zones.length; i++) {
            formats[i] = new SimpleDateFormat("yyyy-MMM-dd HH:mm:ss");
            formats[i].setTimeZone(TimeZone.getTimeZone(zones[i]));
            JLabel label = new JLabel(zones[i]);
            labels[i] = new JLabel(formats[i].format(date));
            panel.add(label);
            panel.add(labels[i]);
        }
        frame.setLayout(new BorderLayout(10, 10));
        frame.add(spinner, BorderLayout.NORTH);
        frame.add(panel, BorderLayout.CENTER);
        frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
        frame.pack();
        frame.setVisible(true);
    }

    public static void main(String[] args) {
        SwingUtilities.invokeLater(new Runnable() {

            @Override
            public void run() {
                new TimeZoneSpinners().makeUI();
            }
        });
    }
}

回答3:

I suspect it's because your JSpinner#getValue() method is returning a Date and you don't need to parse it. You might try replacing with just

Date from = (Date) dateFrom.getValue();

Calling Date.toString() always returns a date in the same default format for the current locale ("Mon Oct 23 00:00:00 ...") which is why you're getting an exception on trying to parse it.

回答4:

You should use

String dosFrom = sdfDestination.format((Date) dateFrom.getValue());

The problem is that dateFrom actually returns the selected date, and Date.toString() doesn't return the date in the format you use.

来源：https://stackoverflow.com/questions/9004038/problems-using-simpledateformat

标签

java

swing

simpledateformat

jspinner