Example of how to save program config in an OS appropriate config file. Specifically, this example shows how to remember the location of a JFileChooser after the program exits.

JFileChooser that remembers

import java.util.*;
import javax.swing.*;
import java.io.*;
import java.nio.charset.Charset;
import java.nio.file.*;
import java.util.logging.Level;
import java.util.logging.Logger;


public class SavedConfigExample {
	static final String KEY_DIRECTORY = "filechooser_directory";
	static final String APPNAME = "Example";
	/**
	 * @param args the command line arguments
	 */
	public static void main(String[] args) {	
	  // load config from last time
		Properties config = new Properties();
		Path lastTimeConfig = getAppFile(APPNAME,"data.properties");
		try{
			if(Files.exists(lastTimeConfig)){
				config.load(Files.newBufferedReader(lastTimeConfig));
			}
		}catch (IOException ex){
			Logger.getLogger(APPNAME).log(Level.WARNING, "Failed to load config file.", ex);
		}
		
		// set file chooser directory to last time's directory
		JFileChooser jfc = new JFileChooser();
		if(config.containsKey(KEY_DIRECTORY)){
			File f = new File(config.getProperty(KEY_DIRECTORY));
			if(f.isDirectory()){
				jfc.setCurrentDirectory(f);
			}
		}
		
		// do something
		jfc.showOpenDialog(null);
		
		// done, save session
		config.setProperty(KEY_DIRECTORY, jfc.getCurrentDirectory().getPath());
		try{
			Files.createDirectories(lastTimeConfig.getParent());
			config.store(Files.newOutputStream(lastTimeConfig), "File comments");
		}catch (IOException ex){
			Logger.getLogger(APPNAME).log(Level.WARNING, "Failed to update config data", ex);
		}
	}
	
	public static Path getAppFolder(String appName){
		Properties sysProps = System.getProperties();
		Path programDir;
		System.err.println(sysProps.getProperty("os.name"));
		switch (sysProps.getProperty("os.name")) {
			case ("Windows Vista"):
			case ("Windows 7"):
			case ("Windows 8"):
			case ("Windows 8.1"):
			case ("Windows NT"):
				programDir = Paths.get(sysProps.getProperty("user.home"), "AppData", "Roaming", appName);
				break;
			case ("Windows XP"):
			case ("Windows 95"):
			case ("Windows 98"):
			case ("Windows 2000"):
				programDir = Paths.get(sysProps.getProperty("user.home"), "Application Data", appName);
				break;
			case ("Mac OS X"):
				programDir = Paths.get(sysProps.getProperty("user.home"), "Library", "Application Support", appName);
				break;
			case ("Linux"):
			case ("Unix"):
			case ("FreeBSD"):
			case ("Digital Unix"):
			case ("Solaris"):
				programDir = Paths.get(sysProps.getProperty("user.home"), "." + appName);
				break;
			default:
				programDir = Paths.get(System.getProperty("user.dir"),"data");
				break;
		}
		return programDir;
	}
	
	public static Path getAppFile(String appName, String... filePath){
		return Paths.get(getAppFolder(appName).toString(), filePath);
	}
}