[Solved] Save and load an ArrayList of Locations

My plugin needs to save and load an ArrayList of Locations. I've been trying to do this using the FileConfiguration API, but I can't figure out how to use an ArrayList for this. Could someone show me an example of saving and loading an ArrayList?

 

Well you can put lists in where other objects go when you use config.set("path", string_list);. But the list needs to be of a primitive data type (int, double, other number types, boolean, or string) otherwise you'll probably get an InvalidConfigurationException.

It's sometimes not the best way, but I've used methods to create and parse location keys in configs before. And I just save it as a String in the file. (it looked like "x0.0y0.0z0.0wWorld" and I used regex to parse the x, y, z, coords and world from it)

 

Ugh, I was trying to avoid parsing strings.
I'll try that then. Thanks for the help.

 

Yeah it seems... wrong lol. You could use a database, but I dont know how to do that.

 

use ObjectOutputStream and ObjectInputStream

Code:

  File      f = new File(this.getDataFolder()+"\\arraylist.dat");
  try{
          if(!f.exists())
              f.createNewFile();
   
          arraylist =  (ArrayList<Type>) new ObjectInputStream( new FileInputStream(f)).readObject();
   
        }catch(Exception e){e.printStackTrace();}
        

Code:

try{
            new ObjectOutputStream(new FileOutputStream(f)).writeObject(arraylist);
        }catch(Exception e){e.printStackTrace();}
 

EDIT: you may want to clear the file after you load it too or you will end up with a whole bunch of arraylist being saved and loaded

 

Aww thats awesome. I've never really gotten into File handling and IO.

 

I tried using your code, and after fixing a few errors, I'm getting this error:

Code:

java.io.NotSerializableException: org.bukkit.Location

I think I'll convert it to a list of Strings instead of Locations when saving and loading, similar to what acuddlyheadcrab suggested.

 

Well if you want to let users edit it, got with yml, but if it were me, i'd prefer a dat file.

 

ahh yes i forgot about that, locations probably isn't serizlizable, although you could create a warpper class

 

That's what I'm doing now.
How did you use regex to parse the string? I've never used regex, but I think it might be simpler than what I was planning to do.

 

Well.... I basically used the replaceAll(String regex, String replacement). There's no way that I know of to simply select the matching regex value, so I had to make my own kind of chunky method that compares 2 strings...

Show Spoiler Hide Spoiler

EDIT: These methods only works for how I use it in this case. regexSelectOne() is the method I was talking about:

Code:java

 public static String toLocKey(Location loc) {
double x = loc.getX(), y = loc.getY(), z = loc.getZ();
String world = loc.getWorld().getName();
String key = (String.format("x%1$sy%2$sz%3$sw%4$s", x, y, z, world));
return key;
}
 
public static Location parseLocKey(String spawnkey) {
double
x = Double.parseDouble(regexSelectOne(spawnkey, "(?<=x).+(?=y)")),
y = Double.parseDouble(regexSelectOne(spawnkey, "(?<=y).+(?=z)")),
z = Double.parseDouble(regexSelectOne(spawnkey, "(?<=z).+(?=w)"))
;
World world = Bukkit.getWorld(regexSelectOne(spawnkey, "(?<=w).+"));
return new Location(world, x, y, z);
}
 
public static String regexSelectOne(String sample, String regex) {
 
/***
* @return the matching string from regex
*/
 
// How it works...
// String sample = "aksjgbaiderpalkgnakg"; String derp = regexSelectOne(sample, "derp");
// "aksjgbai", "alkgnakg" <- split into array between the matching regex
// ^ that and ^that are removed from original string
// leaving only the thing between them, or the matching regex
// However, this only works for one matching regex in the sample. if there were 2 (sample = "aksjgbai derpalkgnakg derp", it would return "derpderp"
 
String[] newstring_arr = sample.split(regex);
for (String temp_string : newstring_arr)
sample = sample.replaceAll(temp_string, "");
return sample;
}

Also, this is a really good way to test regex: http://gskinner.com/RegExr/

EDIT2: This way though.... It just feels so wrong to suggest someone should use it! Just keep in mind it's not the most efficient way and It could yield a couple bugs. There may be a method included in java (like replaceAll()) that already does it, but this works for now.

Edit: Yeah ↓ that way works too. It's basically how I do it, just a whole lot simpler

 

if you store your data into the file in world,x,y,z format you can use the split method of strings to split it up then use Double.parseDouble() on them to extract the data

locations:
- world,92.23213,64,819.213123
- world2,0,64,19.23123123

Code:

list<String> s =  this.getConfig().getStringList("locations");
for(String loc:s){
    String [] arg = loc.split(",");
    Double [] parsed = new Double[3];
        for(int a = 0;a<3;a++){
              parsed[a] = Double.parseDouble(arg[a+1]);
        }
 
  Location location =  new Location  (arg[0],parsed[1],parsed[2],parsed[3]);
}

 

Thanks for all the help! I'll try this tomorrow and edit with the results.

EDIT: It works!

 

Can someone please explain how you did all of this I am really stuck with this also and I cant figure it out. The way you did it is the way I need to but I cant figure out what you are doing in the code! sargunster Double0negative acuddlyheadcrab

 

What do you need help with exactly? I'm re-reading this thread since it was so long ago

EDIT:

(Sorry, it's been a while since I've used the FileConfiguration class by itself, I wrote a library class for it and I've been using that instead for a while now. I'm looking it up though)

 

acuddlyheadcrab How im supposed to save the file. Where do I put the try,catch methods?