Thread: Can't get it to save stuff with JFileChooser

Originally Posted by Norm

Please explain "what I want".


No you can use any file extension that you want. Chose one that won't confuse the OS. Like .dat or .ser

Best way to answer all your questions is to write a small simple program with a small simple class with some data and a get method. Create an object from the small simple class with some data, serialize it to a file, read the object back in and call the method to get the saved data to see it matches what was saved originally.

So do you use writeObject() to serialize it?

If not, how do you serialize it?

do you use writeObject()
Yes

java.io.NotSerializableException: java.io.ObjectOutputStream
at java.io.ObjectOutputStream.writeObject0(Unknown Source)
at java.io.ObjectOutputStream.defaultWriteFields(Unkn own Source)
at java.io.ObjectOutputStream.writeSerialData(Unknown Source)
at java.io.ObjectOutputStream.writeOrdinaryObject(Unk nown Source)
at java.io.ObjectOutputStream.writeObject0(Unknown Source)
at java.io.ObjectOutputStream.writeObject(Unknown Source)
at javax.swing.event.EventListenerList.writeObject(Un known Source)
at sun.reflect.GeneratedMethodAccessor10.invoke(Unkno wn Source)
at sun.reflect.DelegatingMethodAccessorImpl.invoke(Un known Source)
at java.lang.reflect.Method.invoke(Unknown Source)
at java.io.ObjectStreamClass.invokeWriteObject(Unknow n Source)
at java.io.ObjectOutputStream.writeSerialData(Unknown Source)
at java.io.ObjectOutputStream.writeOrdinaryObject(Unk nown Source)
at java.io.ObjectOutputStream.writeObject0(Unknown Source)
at java.io.ObjectOutputStream.defaultWriteFields(Unkn own Source)
at java.io.ObjectOutputStream.defaultWriteObject(Unkn own Source)
at javax.swing.JComponent.writeObject(Unknown Source)
at sun.reflect.NativeMethodAccessorImpl.invoke0(Nativ e Method)
at sun.reflect.NativeMethodAccessorImpl.invoke(Unknow n Source)
at sun.reflect.DelegatingMethodAccessorImpl.invoke(Un known Source)
at java.lang.reflect.Method.invoke(Unknown Source)
at java.io.ObjectStreamClass.invokeWriteObject(Unknow n Source)
at java.io.ObjectOutputStream.writeSerialData(Unknown Source)
at java.io.ObjectOutputStream.writeOrdinaryObject(Unk nown Source)
at java.io.ObjectOutputStream.writeObject0(Unknown Source)
at java.io.ObjectOutputStream.writeArray(Unknown Source)
at java.io.ObjectOutputStream.writeObject0(Unknown Source)
at java.io.ObjectOutputStream.access$300(Unknown Source)
at java.io.ObjectOutputStream$PutFieldImpl.writeField s(Unknown Source)
at java.io.ObjectOutputStream.writeFields(Unknown Source)
at java.awt.Container.writeObject(Unknown Source)
at sun.reflect.NativeMethodAccessorImpl.invoke0(Nativ e Method)
at sun.reflect.NativeMethodAccessorImpl.invoke(Unknow n Source)
at sun.reflect.DelegatingMethodAccessorImpl.invoke(Un known Source)
at java.lang.reflect.Method.invoke(Unknown Source)
at java.io.ObjectStreamClass.invokeWriteObject(Unknow n Source)
at java.io.ObjectOutputStream.writeSerialData(Unknown Source)
at java.io.ObjectOutputStream.writeOrdinaryObject(Unk nown Source)
at java.io.ObjectOutputStream.writeObject0(Unknown Source)
at java.io.ObjectOutputStream.defaultWriteFields(Unkn own Source)
at java.io.ObjectOutputStream.writeSerialData(Unknown Source)
at java.io.ObjectOutputStream.writeOrdinaryObject(Unk nown Source)
at java.io.ObjectOutputStream.writeObject0(Unknown Source)
at java.io.ObjectOutputStream.defaultWriteFields(Unkn own Source)
at java.io.ObjectOutputStream.defaultWriteObject(Unkn own Source)
at javax.swing.JMenu.writeObject(Unknown Source)
at sun.reflect.NativeMethodAccessorImpl.invoke0(Nativ e Method)
at sun.reflect.NativeMethodAccessorImpl.invoke(Unknow n Source)
at sun.reflect.DelegatingMethodAccessorImpl.invoke(Un known Source)
at java.lang.reflect.Method.invoke(Unknown Source)
at java.io.ObjectStreamClass.invokeWriteObject(Unknow n Source)
at java.io.ObjectOutputStream.writeSerialData(Unknown Source)
at java.io.ObjectOutputStream.writeOrdinaryObject(Unk nown Source)
at java.io.ObjectOutputStream.writeObject0(Unknown Source)
at java.io.ObjectOutputStream.writeArray(Unknown Source)
at java.io.ObjectOutputStream.writeObject0(Unknown Source)
at java.io.ObjectOutputStream.access$300(Unknown Source)
at java.io.ObjectOutputStream$PutFieldImpl.writeField s(Unknown Source)
at java.io.ObjectOutputStream.writeFields(Unknown Source)
at java.awt.Container.writeObject(Unknown Source)
at sun.reflect.NativeMethodAccessorImpl.invoke0(Nativ e Method)
at sun.reflect.NativeMethodAccessorImpl.invoke(Unknow n Source)
at sun.reflect.DelegatingMethodAccessorImpl.invoke(Un known Source)
at java.lang.reflect.Method.invoke(Unknown Source)
at java.io.ObjectStreamClass.invokeWriteObject(Unknow n Source)
at java.io.ObjectOutputStream.writeSerialData(Unknown Source)
at java.io.ObjectOutputStream.writeOrdinaryObject(Unk nown Source)
at java.io.ObjectOutputStream.writeObject0(Unknown Source)
at java.io.ObjectOutputStream.writeArray(Unknown Source)
at java.io.ObjectOutputStream.writeObject0(Unknown Source)
at java.io.ObjectOutputStream.access$300(Unknown Source)
at java.io.ObjectOutputStream$PutFieldImpl.writeField s(Unknown Source)
at java.io.ObjectOutputStream.writeFields(Unknown Source)
at java.awt.Container.writeObject(Unknown Source)
at sun.reflect.NativeMethodAccessorImpl.invoke0(Nativ e Method)
at sun.reflect.NativeMethodAccessorImpl.invoke(Unknow n Source)
at sun.reflect.DelegatingMethodAccessorImpl.invoke(Un known Source)
at java.lang.reflect.Method.invoke(Unknown Source)
at java.io.ObjectStreamClass.invokeWriteObject(Unknow n Source)
at java.io.ObjectOutputStream.writeSerialData(Unknown Source)
at java.io.ObjectOutputStream.writeOrdinaryObject(Unk nown Source)
at java.io.ObjectOutputStream.writeObject0(Unknown Source)
at java.io.ObjectOutputStream.writeObject(Unknown Source)
at SongBook.LivingHymns$46.actionPerformed(LivingHymn s.java:2042)
at javax.swing.AbstractButton.fireActionPerformed(Unk nown Source)
at javax.swing.AbstractButton$Handler.actionPerformed (Unknown Source)
at javax.swing.DefaultButtonModel.fireActionPerformed (Unknown Source)
at javax.swing.DefaultButtonModel.setPressed(Unknown Source)
at javax.swing.AbstractButton.doClick(Unknown Source)
at javax.swing.plaf.basic.BasicMenuItemUI.doClick(Unk nown Source)
at javax.swing.plaf.basic.BasicMenuItemUI$Handler.mou seReleased(Unknown Source)
at java.awt.Component.processMouseEvent(Unknown Source)
at javax.swing.JComponent.processMouseEvent(Unknown Source)
at java.awt.Component.processEvent(Unknown Source)
at java.awt.Container.processEvent(Unknown Source)
at java.awt.Component.dispatchEventImpl(Unknown Source)
at java.awt.Container.dispatchEventImpl(Unknown Source)
at java.awt.Component.dispatchEvent(Unknown Source)
at java.awt.LightweightDispatcher.retargetMouseEvent( Unknown Source)
at java.awt.LightweightDispatcher.processMouseEvent(U nknown Source)
at java.awt.LightweightDispatcher.dispatchEvent(Unkno wn Source)
at java.awt.Container.dispatchEventImpl(Unknown Source)
at java.awt.Window.dispatchEventImpl(Unknown Source)
at java.awt.Component.dispatchEvent(Unknown Source)
at java.awt.EventQueue.dispatchEvent(Unknown Source)
at java.awt.EventDispatchThread.pumpOneEventForFilter s(Unknown Source)
at java.awt.EventDispatchThread.pumpEventsForFilter(U nknown Source)
at java.awt.EventDispatchThread.pumpEventsForHierarch y(Unknown Source)
at java.awt.EventDispatchThread.pumpEvents(Unknown Source)
at java.awt.EventDispatchThread.pumpEvents(Unknown Source)
at java.awt.EventDispatchThread.run(Unknown Source)
Exception in thread "AWT-EventQueue-0" java.lang.NullPointerException
at javax.swing.plaf.basic.BasicMenuItemUI.getMenuItem Parent(Unknown Source)
at javax.swing.plaf.basic.BasicMenuItemUI.layoutMenuI tem(Unknown Source)
at javax.swing.plaf.basic.BasicMenuItemUI.getPreferre dMenuItemSize(Unknown Source)
at javax.swing.plaf.basic.BasicMenuItemUI.getPreferre dSize(Unknown Source)
at javax.swing.JComponent.getPreferredSize(Unknown Source)
at javax.swing.BoxLayout.checkRequests(Unknown Source)
at javax.swing.BoxLayout.minimumLayoutSize(Unknown Source)
at java.awt.Container.minimumSize(Unknown Source)
at java.awt.Container.getMinimumSize(Unknown Source)
at javax.swing.JComponent.getMinimumSize(Unknown Source)
at javax.swing.BoxLayout.checkRequests(Unknown Source)
at javax.swing.BoxLayout.preferredLayoutSize(Unknown Source)
at java.awt.Container.preferredSize(Unknown Source)
at java.awt.Container.getPreferredSize(Unknown Source)
at javax.swing.JComponent.getPreferredSize(Unknown Source)
at javax.swing.ScrollPaneLayout.layoutContainer(Unkno wn Source)
at java.awt.Container.layout(Unknown Source)
at java.awt.Container.doLayout(Unknown Source)
at java.awt.Container.validateTree(Unknown Source)
at java.awt.Container.validate(Unknown Source)
at javax.swing.RepaintManager.validateInvalidComponen ts(Unknown Source)
at javax.swing.SystemEventQueueUtilities$ComponentWor kRequest.run(Unknown Source)
at java.awt.event.InvocationEvent.dispatch(Unknown Source)
at java.awt.EventQueue.dispatchEvent(Unknown Source)
at java.awt.EventDispatchThread.pumpOneEventForFilter s(Unknown Source)
at java.awt.EventDispatchThread.pumpEventsForFilter(U nknown Source)
at java.awt.EventDispatchThread.pumpEventsForHierarch y(Unknown Source)
at java.awt.EventDispatchThread.pumpEvents(Unknown Source)
at java.awt.EventDispatchThread.pumpEvents(Unknown Source)
at java.awt.EventDispatchThread.run(Unknown Source)

Go read post#12

Did you understand what the API doc said for that Exception?

How do you get an object to implements the Serializable interface?

I have the entire class implementing Serializable.

Anyway, Serializable has no methods.

Also, so far it appears all of my components on the panel are Serializable.

How did I get that exception thrown then?

How do you get an object to implements the Serializable interface?

To have a class implement an interface:

class ClassName implements Serializable {

How did I get that exception thrown then?

Add this just before the writeObject(theObject):
System.out.println("obj class=" + theObject.getClass()); // show objects class before writing it

Buried in the middle of that long stack trace:
Exception in thread "AWT-EventQueue-0" java.lang.NullPointerException ????<<<<<????

have you written a small test program as I suggested in post#25.
Did you have any problems with it? If so, post the error messages and the source for the small program.
DO NOT POST YOUR HUGH program. Only a small one.

import java.awt.color.ColorSpace;
import java.awt.event.ActionEvent;
import java.awt.event.ActionListener;
import java.awt.event.AdjustmentEvent;
import java.awt.event.ItemEvent;
import java.awt.event.ItemListener;
import java.awt.event.KeyEvent;
import java.awt.event.MouseEvent;
 
import javax.swing.event.MenuEvent;
import javax.swing.event.MenuListener;
import javax.swing.event.PopupMenuEvent;
import javax.swing.event.PopupMenuListener;
import javax.swing.filechooser.FileSystemView;
import javax.swing.text.DefaultStyledDocument;
 
import java.awt.event.ActionEvent;
import java.awt.event.ActionListener;
 
import javax.swing.JButton;
import javax.swing.JFrame;
import javax.swing.JOptionPane;
import javax.swing.JPanel;
import javax.swing.JTextArea;
import javax.swing.ScrollPaneConstants;
 
import java.awt.*;
import java.awt.event.*;
import javax.swing.*;
 
import java.util.*;
import java.util.jar.JarFile;
import java.io.*;
 
import javax.swing.ImageIcon;
 
 
import java.awt.event.WindowEvent;
import java.awt.print.PageFormat;
import java.awt.print.Printable;
import java.awt.print.PrinterException;
import java.awt.print.PrinterJob;
import java.awt.Window;
import javax.swing.JScrollPane;
import java.awt.Component;
import javax.swing.JMenu;
import javax.swing.JMenuItem;
// import acm.io.*;
//import acm.graphics.*;
//import acm.program.*;
//import acm.gui.*;
//import acm.util.*;
import java.awt.Container;
import java.awt.Graphics;
import java.awt.Paint;
import java.awt.PrintJob;
import java.awt.Transparency;
import java.awt.print.*;
 
 
public class loadNSave extends JFrame implements Serializable
{
JButton button, button2, button3, button4, button5;
JTextArea area;
JMenuBar bar;
JMenu menu;
JMenuItem save, load;
JPanel panel;
JScrollPane pane, pane2;
JFrame frame, saveFrame, loadFrame;
File file, file2;
ObjectInputStream inputStr;
ObjectOutputStream outputStr;
FileInputStream pond;
FileOutputStream lake;
JFileChooser chooser, chooser2;
 
public loadNSave() 
{
setTitle("Title");
setVisible(true);
saveFrame = new JFrame();
loadFrame = new JFrame();
button = new JButton("Button");
panel = new JPanel();
pane = new JScrollPane(panel, ScrollPaneConstants.VERTICAL_SCROLLBAR_AS_NEEDED, ScrollPaneConstants.HORIZONTAL_SCROLLBAR_AS_NEEDED);
frame = new JFrame();
button.addActionListener(
new ActionListener() {
public void actionPerformed(ActionEvent e)
{
JOptionPane.showMessageDialog(frame, "Message", "Another Message", JOptionPane.INFORMATION_MESSAGE);
}} );
button2 = new JButton("Button");
button2.addActionListener(
new ActionListener() {
public void actionPerformed(ActionEvent e)
{
JOptionPane.showMessageDialog(frame, "Message", "Another Message", JOptionPane.PLAIN_MESSAGE);
}});
 
button3 = new JButton("Button");
button3.addActionListener(
new ActionListener() {
public void actionPerformed(ActionEvent e)
{
JOptionPane.showMessageDialog(frame, "Message", "Another Message", JOptionPane.QUESTION_MESSAGE);
}} );
 
button4 = new JButton("Button");
button4.addActionListener(
new ActionListener() {
public void actionPerformed(ActionEvent e)
{
JOptionPane.showMessageDialog(frame, "Message", "Another Message", JOptionPane.WARNING_MESSAGE);
}});
 
button5 = new JButton("Button");
button5.addActionListener(
new ActionListener() {
public void actionPerformed(ActionEvent e)
{
JOptionPane.showMessageDialog(frame, "Message", "Another Message", JOptionPane.ERROR_MESSAGE);
}});
 
area = new JTextArea(100, 100);
pane2 = new JScrollPane(area, ScrollPaneConstants.VERTICAL_SCROLLBAR_AS_NEEDED, ScrollPaneConstants.HORIZONTAL_SCROLLBAR_AS_NEEDED);
 
bar = new JMenuBar();
menu = new JMenu("File");
bar.add(menu);
save = new JMenuItem("Save");
load = new JMenuItem("Load");
menu.add(save);
menu.addSeparator();
menu.add(load);
save.addActionListener(
					new ActionListener() {
 
						@Override
						public void actionPerformed(ActionEvent arg0) {
							// TODO Auto-generated method stub
						//	saveDialog.setVisible(true);
 
 
 
							chooser = new JFileChooser();
							chooser.setApproveButtonToolTipText("Click here to save File");
 
 
							chooser.setBackground(Color.GREEN);
							chooser.setFileSelectionMode(JFileChooser.FILES_AND_DIRECTORIES);
 
							 chooser.setVisible(true);
							chooser.showSaveDialog(saveFrame);
							System.out.println(chooser.getSelectedFile());
							file = chooser.getSelectedFile();
							String bob3 = chooser.getSelectedFile().getName();
 
							System.out.println(file.getFreeSpace());
							file.setReadable(true);
							try {
								lake = new FileOutputStream(file);
							} catch (FileNotFoundException e) {
								// TODO Auto-generated catch block
								e.printStackTrace();
							}
							try {
								outputStr = new ObjectOutputStream(lake);
							} catch (IOException e) {
								// TODO Auto-generated catch block
								e.printStackTrace();
							}
 
 
							try {
								outputStr.writeObject(panel);
							} catch (IOException e) {
								// TODO Auto-generated catch block
								e.printStackTrace();
							}
 
 
 
							try {
								outputStr.writeObject(pane2);
							} catch (IOException e) {
								// TODO Auto-generated catch block
								e.printStackTrace();
							}
 
							try {
								outputStr.writeObject(button);
							} catch (IOException e) {
								// TODO Auto-generated catch block
								e.printStackTrace();
							}
 
 
 
						}
 
					});
 
load.addActionListener(
				 new ActionListener() {
					 public void actionPerformed(ActionEvent e)
					 {
						 chooser2 = new JFileChooser();
						 chooser2.setFileSelectionMode(JFileChooser.FILES_AND_DIRECTORIES);
 
						 chooser2.setVisible(true);
						chooser2.showOpenDialog(loadFrame);
 
						System.out.println(chooser2.getSelectedFile());
						file2 = chooser2.getSelectedFile();
 
 
						String bob = file2.getName() + " doesn't exist!";
						String bob2 = file2.getName() + " does exist.";
 
						if (file2.exists() == true)
						{
							JOptionPane.showMessageDialog(null, "File exists", bob2, JOptionPane.INFORMATION_MESSAGE);
						}
 
						else if (file2.exists() == false)
						{
							JOptionPane.showMessageDialog(null, "File not found", bob, JOptionPane.ERROR_MESSAGE);
						}
 
						try {
							pond = new FileInputStream(file2);
						} catch (FileNotFoundException e1) {
							// TODO Auto-generated catch block
							e1.printStackTrace();
						}
						try {
							inputStr = new ObjectInputStream(pond);
						} catch (IOException e1) {
							// TODO Auto-generated catch block
							e1.printStackTrace();
						}
						try {
							pond.read();
						} catch (IOException e1) {
							// TODO Auto-generated catch block
							e1.printStackTrace();
						}
						try {
							pond.getFD();
						} catch (IOException e1) {
							// TODO Auto-generated catch block
							e1.printStackTrace();
						}
						try {
							System.out.println(pond.getFD());
						} catch (IOException e1) {
							// TODO Auto-generated catch block
							e1.printStackTrace();
						}
 
						try {
							inputStr.readObject();
						} catch (IOException e2) {
							// TODO Auto-generated catch block
							e2.printStackTrace();
						} catch (ClassNotFoundException e2) {
							// TODO Auto-generated catch block
							e2.printStackTrace();
						}
 
						System.out.println(pond.getChannel());
 
						System.out.println(pond.getChannel().isOpen());
 
						System.out.println(file2.canRead());
						System.out.println(file2.canExecute());
						System.out.println(file2.getTotalSpace());
						file2.setExecutable(true);
 
					 }
				 });
panel.add(button);
panel.setVisible(true);
panel.add(button2);
panel.add(button3);
panel.add(button4);
panel.add(button5);
panel.add(pane2);
panel.add(bar);
bar.setVisible(true);
 
 
 
 
 
getContentPane().add(pane);
}
 
public static void main(String[]args)
{
loadNSave ref = new loadNSave();
}
 
 
}

The problems are that it won't close even after I click the x.

Also, it doesn't appear to save or load correctly, as it's not bringing up the new stuff.

Also, no error messages are being generated.

I''m only getting error messages with huge program.

However, small program doesn't appear to be able to load and save properly either.

Do I need to get it to remove all the components first before reading in the objects?

Also, when I serialize the JPanel, does it have to serialize the ObjectINputStream itself, because that class isn't serializable.

A 300 line file is not a small program.
You don't need any GUI to test Serialization with. Just some classes to write and read back.
The frame doesn't show any components and doesn't handle window closing.

Try again. This test program is too hand to work with.

Wait, can I get it to write an entire program, like have a small program, then have, in another file in the Eclipse project, write the first class into the ObjectOutputStream?

Is that what you meant?

I'm afraid I don't quite understand what you're saying.

I don't think my big file can serialize the graphics the paint method put in; that may be part of the problem.

How do I deal with that?

How do you read and write the not Serializable stuff?

I was going to make a bit of code that would check each item and use a try and catch block to check if it's serializable, and if it's not, to make it read and write anyway as I read there's a way to do it, but I have to do something with all of its fields and stuff like that.

Do you mean by fields all the stuff under Fields in the javaDoc online?

Also, to load, do I have to clear the current components visible first before it'll work?

I haven't read the entire thread, but it looks to me like you can do whatever it is you're doing with java.util.prefs.Preferences

db