Saving a filename in Preferences

[Adam Cripps]

I want my app to store the last used file so that the next time the user opens up the application the file is loaded automatically.

I'm using Preferences to store this. However, when I store the filename, it seems to save the swing widget instead, which means I get an error when the application loads next time.

Code to save the filename:

if (e.getActionCommand().equals("Save")){
			//tabbedpane has a list of subjects - we go through them and get the items for each one. 
			ListIterator textfieldsIter = tabbedpane.subjectPanels.listIterator(); 
			while(textfieldsIter.hasNext()){
				CurriculumSubject subject = (CurriculumSubject) textfieldsIter.next();
			}
			savefc = new JFileChooser(); 
			savefc.showSaveDialog(frame); 
			if(savefc.getSelectedFile()!=null){
				theFileToSave = savefc.getSelectedFile();  
				try {
				    BufferedWriter out = new BufferedWriter(new FileWriter(theFileToSave));
				    String outtext = itemslist.toString();
				    out.write(outtext);
				    out.close();
					String filename = theFileToSave.toString();
					prefs.put("filename", filename);
					System.out.println("Saving --- I've just put " + filename + " to prefs." );
					updatePrefs();
				} catch (IOException exc) {
					exc.printStackTrace();
				}
			}

 public void updatePrefs( )  // Store current filenames and/or subjectList
	   {
		 for(int i=0;i<subjectList.length;i++){
			 prefs.put(subjectTitles[i], subjectList[i]);
			 try {
				prefs.flush();
			} catch (BackingStoreException e) {
				// TODO Auto-generated catch block
				e.printStackTrace();
			}
		 }
	   }

Code in the constructor trying to load the filename:

public JReport(){
		//Preferences is going to store everything. 	
		prefs = java.util.prefs.Preferences.userNodeForPackage (this.getClass());
		for(int i=0;i<subjectTitles.length;i++){
			System.out.println("subjectTitles["+i+"] " + prefs.get(subjectTitles[i], "not set"));
		}
		boolean alreadyRun = prefs.getBoolean("firstrun", true); //This sets up a default in case one doesn't already exist. 
		runFirst = this.getPrefsFirst(); 
		//Let's check if this is our first run - if it is we will set some defaults up
		if (alreadyRun ==true){
		String [] subjectList  = {"Maths", "Space and shape", "Measures", "Data", "Reading", "Writing", 
						"Speaking", "Listening", "Science", "ICT", "Geography", "History", "R.E.", "PSHE", "P.E"};
				this.setGui(subjectList);
				tabbedpane.setTabTitles(subjectList);
			for (int i=0;i<subjectList.length;i++){
				
				// This causes a problem. 
				
				String key = subjectTitles[i];
				String subject = subjectList[i];
				prefs.put(key,subject); //Not sure why but I keep using set instead of put for preferences. 
				//TODO - I need to check what this is like on a machine that hasn't had a run on this before
				//TODO - e.g. does the gui get set up? 
				}
				
			}
			else { 
			
				// Here, we're going to get the preferences, 
				//put them in subjectList and then call tabbedpane.setTabTitles(subjectList);
				for (int i=0; i<subjectList.length;i++){
					String key = subjectTitles[i];
					String def="Subject " + Integer.toString(i);
					subjectList[i]=prefs.get(key, def);
					String filename = prefs.get("filename", "/home/adam/dummy.txt");
					System.out.println("And filename is ... " + filename);
				}
				this.setGui(subjectList); // Now we've populated subjectList - it's time to create the gui.
				//Now time to open any file that was previously used. 
				String defaultfile = ""; 
				String filetoopen = prefs.get("file", defaultfile);
				System.out.println("I was trying to open " + filetoopen);
				//This is currently card-coded in and works, but will need to investigate pullingn file from prefs. 
				try {
					System.out.println("I'm trying to open the file as I'm starting ... " + filetoopen);
					File filetoopenfile = new File(filetoopen.toString());
					tabbedpane.setItemsFromFile(filetoopenfile);
				} catch (FileNotFoundException e1) {
					// TODO Auto-generated catch block
					e1.printStackTrace();
				}
			}
		this.getPrefs();
		
		}

The error I get when the code runs:

I was trying to open javax.swing.JFileChooser[,0,0,0x0,invalid,layout=java.awt.BorderLayout,alignmentX=0.5,
alignmentY=0.0,border=sun.swing.plaf.synth.SynthFileChooserUI$UIBorder@5ae8a0cd,flags=320,
maximumSize=,minimumSize=,preferredSize=,approveButtonText=,currentDirectory=/home/adam,dialogTitle=,
dialogType=OPEN_DIALOG,fileSelectionMode=FILES_ONLY,returnValue=ERROR_OPTION,selectedFile=,
useFileHiding=true]
I'm trying to open the file as I'm starting ... javax.swing.JFileChooser[,0,0,0x0,invalid,layout=java.awt.BorderLayout,alignmentX=0.5,
alignmentY=0.0,border=sun.swing.plaf.synth.SynthFileChooserUI$UIBorder@5ae8a0cd,
flags=320,maximumSize=,minimumSize=,preferredSize=,approveButtonText=,currentDirectory=/home/adam,dialogTitle=,
dialogType=OPEN_DIALOG,fileSelectionMode=FILES_ONLY,returnValue=ERROR_OPTION,
selectedFile=,useFileHiding=true]
java.io.FileNotFoundException: javax.swing.JFileChooser[,0,0,0x0,invalid,layout=java.awt.BorderLayout,alignmentX=0.5,
alignmentY=0.0,border=sun.swing.plaf.synth.SynthFileChooserUI$UIBorder@5ae8a0cd,flags=320,
maximumSize=,minimumSize=,preferredSize=,approveButtonText=,currentDirectory=/home/adam,dialogTitle=,
dialogType=OPEN_DIALOG,fileSelectionMode=FILES_ONLY,returnValue=ERROR_OPTION,
selectedFile=,useFileHiding=true] (No such file or directory)
	at java.io.FileInputStream.open(Native Method)

Any ideas gratefully received.
TIA
Adam

[Rob Spoor]

You write to preference key filename but read from key file. Is that correct?

Also, I would prefer theFileToSave.getAbsolutePath() instead of theFileToSave.toString(), as the latter may return a relative path that in turn may lead to unexpected results if the base path changes.

[Adam Cripps]

Rob - many thanks - that was exactly the problem (the file and filename clash).

[Rob Spoor]

You're welcome