How to save a hashmap?

Pretty new at programing in Java, so please bear with me.

I have a HashMap<String, Location>, and I need to save it to a file or a database so it persists through server restarts. So far, I know that I could save it to a MySQL database (no clue how to do this), create a custom class that would make a serializable location and serialize it (no clue here either), use .toString() and then find a way to recover it to a hashmap, or break it down into its component parts and save those to a text file. Which of these would be easiest/best?

 

If you need to save the data in a file as binary format, you can use the SLAPI from the Plugin Tutorial on the Wiki:

http://wiki.bukkit.org/Plugin_Tutorial#Saving.2FLoading_a_HashMap

 

You can do what I did when I started programming :

1. create a file

Code:java

File file = new File(this.getDataFolder, "filename.dat");
if(!file.exsits()){
try{
file.createNewFile();
}catch(IOException ex){
System.out.println("file creation failed!");
}
}
 

2. convert location to string method

Code:java

public String locToString(Location loc){
String wname = loc.getWorld().getName();
String x = loc.getX().toString();
String y = loc.getY().toString();
String z = loc.getZ().toString();
String str = String.format("%s, %s, %s, %s",wname ,x ,y, z);
return str;
}

3. create a writing method

Code:java

public void write(File file, HashMap<String, Location> data){
//using a formatter to write to a file
Formatter formatter;
try{
formatter = new Formatter(file);
catch(FileNotFoundException ex){
System.out.println("Failed to find the desired file");
}
//creating a for loop
for(String s : data.ketSet()){
formatter.format("%s: %s", s, locToString(data.get(s)));
}
formatter.close();
}

Done, all saved.

4. converting string data to Location data:

Code:java

public Location stringToLoc(String s){
String[] data = s.split(", ");
World w = getServer().getWorld(data(0));
double x = Double.parseDouble(data(1));
double y = Double.parseDouble(data(2));
double z = Double.parseDouble(data(3));
return new Location(w, x, y, z);
}

5. reading files using scanner

Code:java

public HashMap<String, Location> read(File file){
HashMap<String, Location> data = new HashMap<String, Location>();
Scanner scanner;
try{
scanner = new Scanner(file);
catch(FileNotFoundException ex){
System.out.println("Failed to find the desired file");
}
while(scanner.hasNextLine()){
String[] line = scanner.nextLine().split(": ");
data.put(line(0), stringToLoc(line(1)));
}
scanner.close();
return data;
}

You can also use bukkit configuration instead of scanner/ formatter but it's up to you.
Note that you might get some errors because it's possible that I mispelled some methods (it's hard to write every thing correctly using a minigalaxy cellphone xD). make sure to correct any spelling error (once again, sorry if there are any) and enjoy

edit : the method in the comment above this one is probably more simple