write java.util.logging to a file

Question

While I'm aware of Log4J , and I'm sure there are others, I'm using java.util.logging to write to a file.

The error originates in nextTitleActionPerformed which is near the bottom of the soure code.

I've looked at a few questions on SO, but must be misunderstanding the mechanism for logging to a file.

However, logging to a file results in a NullPointerException as below:

BUILD SUCCESSFUL
Total time: 3 seconds
Jul 27, 2014 12:21:50 AM net.bounceme.dur.client.gui.LoggingGUI <init>
INFO: starting log..
Exception in thread "AWT-EventQueue-0" java.lang.NullPointerException
    at net.bounceme.dur.client.gui.LoggingGUI.nextTitleActionPerformed(LoggingGUI.java:103)
    at net.bounceme.dur.client.gui.LoggingGUI.access$000(LoggingGUI.java:10)
    at net.bounceme.dur.client.gui.LoggingGUI$2.actionPerformed(LoggingGUI.java:56)
    at javax.swing.AbstractButton.fireActionPerformed(AbstractButton.java:2018)
    at javax.swing.AbstractButton$Handler.actionPerformed(AbstractButton.java:2341)
    at javax.swing.DefaultButtonModel.fireActionPerformed(DefaultButtonModel.java:402)
    at javax.swing.DefaultButtonModel.setPressed(DefaultButtonModel.java:259)
    at javax.swing.plaf.basic.BasicButtonListener.mouseReleased(BasicButtonListener.java:252)
    at java.awt.Component.processMouseEvent(Component.java:6505)
    at javax.swing.JComponent.processMouseEvent(JComponent.java:3311)
    at java.awt.Component.processEvent(Component.java:6270)
    at java.awt.Container.processEvent(Container.java:2229)
    at java.awt.Component.dispatchEventImpl(Component.java:4861)
    at java.awt.Container.dispatchEventImpl(Container.java:2287)
    at java.awt.Component.dispatchEvent(Component.java:4687)
    at java.awt.LightweightDispatcher.retargetMouseEvent(Container.java:4832)
    at java.awt.LightweightDispatcher.processMouseEvent(Container.java:4492)
    at java.awt.LightweightDispatcher.dispatchEvent(Container.java:4422)
    at java.awt.Container.dispatchEventImpl(Container.java:2273)
    at java.awt.Window.dispatchEventImpl(Window.java:2719)
    at java.awt.Component.dispatchEvent(Component.java:4687)
    at java.awt.EventQueue.dispatchEventImpl(EventQueue.java:735)
    at java.awt.EventQueue.access$200(EventQueue.java:103)
    at java.awt.EventQueue$3.run(EventQueue.java:694)
    at java.awt.EventQueue$3.run(EventQueue.java:692)
    at java.security.AccessController.doPrivileged(Native Method)
    at java.security.ProtectionDomain$1.doIntersectionPrivilege(ProtectionDomain.java:76)
    at java.security.ProtectionDomain$1.doIntersectionPrivilege(ProtectionDomain.java:87)
    at java.awt.EventQueue$4.run(EventQueue.java:708)
    at java.awt.EventQueue$4.run(EventQueue.java:706)
    at java.security.AccessController.doPrivileged(Native Method)
    at java.security.ProtectionDomain$1.doIntersectionPrivilege(ProtectionDomain.java:76)
    at java.awt.EventQueue.dispatchEvent(EventQueue.java:705)
    at java.awt.EventDispatchThread.pumpOneEventForFilters(EventDispatchThread.java:242)
    at java.awt.EventDispatchThread.pumpEventsForFilter(EventDispatchThread.java:161)
    at java.awt.EventDispatchThread.pumpEventsForHierarchy(EventDispatchThread.java:150)
    at java.awt.EventDispatchThread.pumpEvents(EventDispatchThread.java:146)
    at java.awt.EventDispatchThread.pumpEvents(EventDispatchThread.java:138)
    at java.awt.EventDispatchThread.run(EventDispatchThread.java:91)
thufir@dur:~/NetBeansProjects/Log$ 

Apparently, I'm not attaching the handler correctly?

code:

package net.bounceme.dur.client.gui;

import java.io.IOException;
import java.sql.Timestamp;
import java.util.Date;
import java.util.logging.FileHandler;
import java.util.logging.Level;
import java.util.logging.Logger;

public final class LoggingGUI extends javax.swing.JFrame {

    private static final Logger log = Logger.getLogger(LoggingGUI.class.getName());
    private Title title = null;
    private FileHandler fh = null;

    public LoggingGUI() throws IOException {
        initComponents();
        fh = new FileHandler("gui.log");
        log.addHandler(fh);
        log.setLevel(Level.ALL);
        log.info("starting log..");
    }

    public static void main(String... args) {
        java.awt.EventQueue.invokeLater(new Runnable() {
            @Override
            public void run() {
                try {
                    new LoggingGUI().setVisible(true);
                } catch (IOException ex) {
                    Logger.getLogger(LoggingGUI.class.getName()).log(Level.SEVERE, null, ex);
                }
            }
        });
    }

    /**
     * This method is called from within the constructor to initialize the form.
     * WARNING: Do NOT modify this code. The content of this method is always
     * regenerated by the Form Editor.
     */
    @SuppressWarnings("unchecked")
    // <editor-fold defaultstate="collapsed" desc="Generated Code">                          
    private void initComponents() {

        stateGroup = new javax.swing.ButtonGroup();
        jTabbedPane1 = new javax.swing.JTabbedPane();
        titlePanel = new javax.swing.JPanel();
        nextTitle = new javax.swing.JButton();

        setDefaultCloseOperation(javax.swing.WindowConstants.EXIT_ON_CLOSE);

        nextTitle.setText("next");
        nextTitle.addActionListener(new java.awt.event.ActionListener() {
            public void actionPerformed(java.awt.event.ActionEvent evt) {
                nextTitleActionPerformed(evt);
            }
        });

        javax.swing.GroupLayout titlePanelLayout = new javax.swing.GroupLayout(titlePanel);
        titlePanel.setLayout(titlePanelLayout);
        titlePanelLayout.setHorizontalGroup(
            titlePanelLayout.createParallelGroup(javax.swing.GroupLayout.Alignment.LEADING)
            .addGroup(titlePanelLayout.createSequentialGroup()
                .addGap(94, 94, 94)
                .addComponent(nextTitle, javax.swing.GroupLayout.PREFERRED_SIZE, 557, javax.swing.GroupLayout.PREFERRED_SIZE)
                .addContainerGap(144, Short.MAX_VALUE))
        );
        titlePanelLayout.setVerticalGroup(
            titlePanelLayout.createParallelGroup(javax.swing.GroupLayout.Alignment.LEADING)
            .addGroup(titlePanelLayout.createSequentialGroup()
                .addGap(73, 73, 73)
                .addComponent(nextTitle, javax.swing.GroupLayout.PREFERRED_SIZE, 286, javax.swing.GroupLayout.PREFERRED_SIZE)
                .addContainerGap(101, Short.MAX_VALUE))
        );

        jTabbedPane1.addTab("tab1", titlePanel);

        javax.swing.GroupLayout layout = new javax.swing.GroupLayout(getContentPane());
        getContentPane().setLayout(layout);
        layout.setHorizontalGroup(
            layout.createParallelGroup(javax.swing.GroupLayout.Alignment.LEADING)
            .addGroup(layout.createSequentialGroup()
                .addGap(26, 26, 26)
                .addComponent(jTabbedPane1, javax.swing.GroupLayout.PREFERRED_SIZE, 803, javax.swing.GroupLayout.PREFERRED_SIZE)
                .addContainerGap(30, Short.MAX_VALUE))
        );
        layout.setVerticalGroup(
            layout.createParallelGroup(javax.swing.GroupLayout.Alignment.LEADING)
            .addGroup(layout.createSequentialGroup()
                .addContainerGap()
                .addComponent(jTabbedPane1)
                .addContainerGap())
        );

        pack();
    }// </editor-fold>                        

    private void nextTitleActionPerformed(java.awt.event.ActionEvent evt) {                                          
        title = null;
        Date date = new Date();
        Timestamp timestamp = new Timestamp(date.getTime());
        log.info(title.toString());
        title.setTitle("modified from GUI");
    }                                         


    // Variables declaration - do not modify                     
    private javax.swing.JTabbedPane jTabbedPane1;
    private javax.swing.JButton nextTitle;
    private javax.swing.ButtonGroup stateGroup;
    private javax.swing.JPanel titlePanel;
    // End of variables declaration                   

}




handlers=java.util.logging.FileHandler, java.util.logging.ConsoleHandler

.level=ALL

myapp.ui.level=ALL
myapp.business.level=CONFIG
myapp.data.level=SEVERE
net.bounceme.dur.level=ALL

java.util.logging.ConsoleHandler.level=SEVERE
java.util.logging.ConsoleHandler.formatter=java.util.logging.SimpleFormatter

java.util.logging.FileHandler.level=ALL

java.util.logging.FileHandler.pattern=%h/java%u.log

java.util.logging.FileHandler.limit=50000

java.util.logging.FileHandler.count=1

java.util.logging.FileHandler.formatter=java.util.logging.SimpleFormatter 

clicking the button causes the error.

see also:

http://www.javapractices.com/topic/TopicAction.do?Id=143

Answer 1

while youre right that most devs shun java.util.logging in favor of something better, your issue isnt related to logging at all:

title = null; <---- null
Date date = new Date();
Timestamp timestamp = new Timestamp(date.getTime());
log.info(title.toString());  <---- STILL null
title.setTitle("modified from GUI");