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Configuration API Reference

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The Configuration API is a set of tools to help developers quickly parse and emit configuration files that are human readable and editable. Despite the name, the API can easily be used to store plugin data in addition to plugin configuration. Presently only YAML configurations can be used. The API however was designed to be extensible and allow for other implementations.

The Configuration API can be found in the org.bukkit.configuration and org.bukkit.configuration.file packages. Plugins that were created before version 1.1-R5 may have used an older and different implementation that resided in org.bukkit.util.configuration. These implementations are not compatible and the old package has since been removed.

This introduction assumes that you have some knowledge about proper object oriented design, Java, and the core design of Bukkit plugins. This page is not a substitute for the JavaDocs for the FileConfiguration Class

Basic Topics[edit | edit source]

The Configuration Object[edit | edit source]

Your plugin extends JavaPlugin, and in doing so, you inherited methods and fields from JavaPlugin. The inherited method, getConfig() returns an object of type FileConfiguration. This is the object that represents config.yml inside your plugin's data folder.

The first time getConfig() is invoked on your plugin, config.yml is loaded from disk, and default values are loaded from the jar. Subsequent invocations of getConfig() will return the existing FileConfiguration object that is in memory. Operations performed on this object will not be written to disk unless explicitly saved. Likewise, any modifications done after the file has been loaded will not be reflected in the object. If config.yml does not exist in your data folder, it is equivalent to an empty config.yml, and will load an empty FileConfiguration.

Warning Warning: if you assign the returned object from getConfig() DO NOT assign it to a static field
Warning Warning: if you do the above, assign getConfig() to the variable AGAIN after a reloadConfig

Lightbulb.png Note: it is better to just use getConfig() instead of assigning it to an instance variable

Keys[edit | edit source]

A configuration file is organized into key value pairs where all keys are Strings. The value for the other keys may be a ConfigurationSection or a single piece of data. The getKeys(boolean) method returns the set of keys for the current FileConfigurationSection. The boolean value determines if the returned set is recursive, if true it will return the keys of the given section and their children keys, if false will only return keys of the given section. To get the keys of a particular section, the getKeys(boolean) method must be invoked on that particular section. To get the section you will have to invoke getConfigurationSection(String).

Lightbulb.png Note: The getKeys method returns a Set of Strings

Paths[edit | edit source]

The Configuration API uses Paths to form a unique key to value pairs. A path is the set of keys used to associate a value. Each level is separated by the path separator, which is by default the '.' (period). For example the following YAML file has the following set of paths.

key: value
  two: value
    - values
    - values
    - values
    five: value
    six: value
    seven: value
  • key
  • one
  • one.two
  • one.three
  • one.four
  • one.four.five
  • one.*
  • one.*.six
  • one.*.seven

Default Values[edit | edit source]

A default config.yml should be provided in your jar for users. In the event that a config.yml is missing or incomplete, values will be loaded from included config.yml. The provided file must be named config.yml and be placed in the same directory as your plugin.yml. The file should have the intended structure of your config.yml. This file can be copied as is into the datafolder by invoking saveDefaultConfig() on the Appropriate instance of JavaPlugin.


If dynamic key-value pairs are required as default values, they can added as defaults to the configuration with invocations of addDefault(String, Object) and addDefaults(Map<String,Object>) methods.

In certain cases if you wish to append new key-value pairs to an existing config.yml you can set the copyDefaults to true for the ConfigurationOptions object.


Creating a copy of config.yml[edit | edit source]

You can create a copy of config.yml from the jar into the plugin's data folder by invoking JavaPlugin's saveDefaultConfig() method. saveDefaultConfig() will not overwrite an existing file.

Getting Values[edit | edit source]

Reading values from the configuration involves invoking one of the many getter methods. A complete list of getters can be found here. Every getter method takes a configuration path detailed above. Some of the commonly used getter methods are as follows

  • getBoolean(String)
  • getInt(String)
  • getString(String)
  • getList(String)
  • getStringList(String)

HashMaps[edit | edit source]

In the case of HashMaps as a value, they are treated differently than other forms of data. There is a restriction for Map types. It must use a String as a key, and the value but be either a boxed primitive, String, List, Map, or a ConfigurationSerializable type. They will lose their type.

To get a HashMap, a ConfigurationSection must must first be retrieved. You can return the configuration with getConfigurationSection method. The getValues method will return the values in the ConfigurationSection as a map, it takes a boolean which controls if the nested maps will be returned in the map. You can obtain the original map by invoking getValues(false) on the returned ConfigurationSection. Due to the way Java handles generic classes, type information will be lost, thus a cast will need to be performed to set the original type information. The API makes no guarantees that the cast you perform will be safe.


Setting Values[edit | edit source]

Writing values involves invoking the set(String, Object) method on an instance of Configuration. Unlike the different get methods that FileConfiguration has, there is only one set method. Not all objects can be set, only primitive types, String, Lists, and types that implement ConfigurationSerializable, such as Vector and ItemStack, can be set. To erase a value supply null as a parameter. All changes made by set will only affect the copy of the configuration in memory, and will not persist beyond restarting the server until the configuration is saved. Following are some example uses:

// setting a boolean value
this.getConfig().set("", true);
// setting a String
String stringValue = "Hello World!";
this.getConfig().set("", stringValue);
// setting an int value
int integerValue = 8;
this.getConfig().set("", integerValue);
// Setting a List of Strings
// The List of Strings is first defined in this array
List<String> listOfStrings = Arrays.asList("Hello World", "Welcome to Bukkit", "Have a Good Day!");
this.getConfig().set("", listOfStrings);
// Setting a vector
// event is assumed to be an existing event inside an "onEvent" method.
Vector vector = event.getPlayer().getLocation().toVector();
this.getConfig().set("", vector);
// Erasing a value
this.getConfig().set("", null);

HashMaps[edit | edit source]

When HashMaps are used as a value, they are treated slightly differently. The Map must parameterized with a String type for the key, and the value must be parameterized as a boxed primitive, String, List, Map, or a ConfigurationSerializable.

While you can use the set method to directly set a HashMap to a key, you cannot directly retrieve the Map back with the get method after reading directly from disk. The context above is to minimize unpredictability.

To set a HashMap, a ConfigurationSection must be created for that HashMap. You can only set HashMap where the key is a string the the value is something that is ConfigurationSerializable. The createSectionMethod

this.getConfig().createSection(String path, Map< String, Object > map)

Saving the File[edit | edit source]

If make any changes to theFileConfiguration with set methods, or mutate any Lists, you will need to save the changes to disk if you wish to keep these changes after the plugin is disabled. To save the file to disk invoke the saveConfig method for your plugin, it will overwrite the file already there.

Reloading from Disk[edit | edit source]

If you suspect that users have made changes to the config.yml in the data folder, those changes are not reflected in memory. Invoke the reloadConfig() method of your plugin to load from the disk again. It will destroy all changes in memory.

Using an alternate configuration file[edit | edit source]

If for whatever reason you need another configuration file, you can use YamlConfiguration to make a new one.

FileConfiguration data = YamlConfiguration.loadConfiguration(new File(getDataFolder(), "data.yml"));

This reads the file data.yml from your data folder, and returns a FileConfiguration. If the file does not exist, the FileConfiguration is empty. If you need a pre-made FileConfiguration to be used, you can instead use an InputStream.

FileConfiguration data = YamlConfiguration.loadConfiguration(getResource("data.yml"))

This takes the InputStream from getResource, which gets a file embedded in the jar, and retreives a FileConfiguration from that.

Advanced Topics[edit | edit source]

The following are some more advanced topics, meant for more advanced plugins. If you only require the default config.yml, creating custom methods for reading, and saving, you will not need to go this far.

Options[edit | edit source]

Every FileConfiguration instance is associated with a FileConfigurationOptions object. The FileConfigurationOptions object controls the behavior of the FileConfiguration it is associated with. FileConfiguration's options() method returns the FileConfigurationOption's responsible for it. With it you can check and set each option. There are currently four options. Be aware that the methods are overloaded, for example copyDefaults() which returns a boolean and copyDefaults(boolean) which returns it self, but has a side effect which changes the state.

CopyDefaults[edit | edit source]

The copyDefaults option changes the behavior of Configuration's save method. By default, the defaults of the configuration will not be written to the target save file. If set to true, it will write out the default values, to the target file. However, once written, you will not be able to tell the difference between a default and a value from the configuration.

PathSeperator[edit | edit source]

PathSeperator changes the character that is used to separate the different levels of the configuration. By default it is the "." (period) but it can be changed to any char.

Header[edit | edit source]

Header is the comment block at the top of a YAML file, it is applied to the save output. The header is the only comment that Configuration API knows how to copy.

copyHeader[edit | edit source]

If copyHeader() returns true then the header will be copied on save, from the default source.

Arbitrary Configurations[edit | edit source]

If you require additional YAML files, for storing configuration information or persisting additional game information you will need to write your own methods for accessing the additional configuration files. Modeled after JavaPlugin getConfig, reloadConfig, saveConfig methods, the following is an example how to write your own methods to read and save to custom configuration files. Since these config files belong to your plugin, you can put this method in your main class so that you can have the same access as you have with config.yml. You will have to write a set of these methods for each YAML file. The advantage here, is that you can use each set in the same manner as the provided methods for the default config.yml. Alternately, adding additional methods can keep the method count lower and allow access to multiple files.

Mirroring the JavaPlugin implementation[edit | edit source]

JavaPlugin implements methods for config.yml. A plugin needs to implement its own methods to access configuration files unique to the plugin. After implementing the methods for the plugin, they can be invoked in the same context as the inherited getConfig(), reloadConfig(), saveConfig(), and saveDefaultConfig() methods from JavaPlugin. The following can be made into a single class which allows access to any yaml file. Such a class can be found here

First you will need to declare two fields and initialize them to null for each of the custom configuration files. One to hold the FileConfiguration object and one to hold the File object. The File object represents the file on the disk, and the FileConfiguration represents the contents of the configuration.

private FileConfiguration customConfig = null;
private File customConfigFile = null;
Implementation for Reloading[edit | edit source]
Then, write the method that is responsible for loading the config from disk. It will load the file, and search the jar for a default customConfig.yml.
public void reloadCustomConfig() {
    if (customConfigFile == null) {
    customConfigFile = new File(getDataFolder(), "customConfig.yml");
    customConfig = YamlConfiguration.loadConfiguration(customConfigFile);
    // Look for defaults in the jar
    Reader defConfigStream = new InputStreamReader(this.getResource("customConfig.yml"), "UTF8");
    if (defConfigStream != null) {
        YamlConfiguration defConfig = YamlConfiguration.loadConfiguration(defConfigStream);
Implementation for Getting[edit | edit source]
Next, you need to write the getter method. Check if customConfig is null, if it is load from disk.
public FileConfiguration getCustomConfig() {
    if (customConfig == null) {
    return customConfig;
Implementation for Saving[edit | edit source]
Finally, write the save method, which saves changes and overwrites the file on disk.
public void saveCustomConfig() {
    if (customConfig == null || customConfigFile == null) {
    try {
    } catch (IOException ex) {
        getLogger().log(Level.SEVERE, "Could not save config to " + customConfigFile, ex);
Implementation for Defaults[edit | edit source]
Optionally, you may want to write a method that mimics JavaPlugin's saveDefaultConfig() method.
public void saveDefaultConfig() {
    if (customConfigFile == null) {
        customConfigFile = new File(getDataFolder(), "customConfig.yml");
    if (!customConfigFile.exists()) {            
         plugin.saveResource("customConfig.yml", false);

Serializing and Deserializing Objects[edit | edit source]

The Configuration API, as mentioned above can store Java objects that implement the ConfigurationSerializable Interface. Object serialization facilitates easy saving and loading so plugin authors can focus on other parts of their plugin. It greatly simplifies tasks such as storing a Location in YAML, a developer can serialize a wrapper class, which provide methods to retrieve a Location.

Classes, in addition to implementing the ConfigurationSerializable interface must also implment one of the following as noted in the Javadoc, so that they can be serialized by the API:

  • A constructor that accepts a single Map.
  • A static method "deserialize" that accepts a single Map and returns the class.
  • A static method "valueOf" that accepts a single Map and returns the class.

In order for a serialized object to be deserialized, it must also be registered with ConfigurationSerialization. The static registerClass method must be invoked once per class that has been serialized.

This statement must be placed in your onEnable method or some other location that gets called every time your plugin is initialized:

ConfigurationSerialization.registerClass(Class<? extends ConfigurationSerializable>)

Warning Warning: Do not use a static block to execute the above; if you do so, it will not be called a second time when /reload is used and you will encounter errors due to it not being registered!

Aliases[edit | edit source]

When classes are serialized they are marked with their fully qualified name.

You can provide an alias to your class so that it does not serialize with the fully qualified name of your class, but the alias instead. You provide the alias with the SerializableAs annotation to the class implementing ConfigurationSerializable.
When registering a class with an alias, the alias must be provided on registration.
ConfigurationSerialization.registerClass(Class<? extends ConfigurationSerializable>, String)

Example Use[edit | edit source]

Below is the an example plugin that uses the new Configuration API to be display messages as an MOTD as players join, and for the player to retrieve the rules on command. It does not follow proper style and plugin layout to keep the number of lines to a minimum.

import java.util.*;
import org.bukkit.command.*;
import org.bukkit.event.*;
import org.bukkit.configuration.file.FileConfiguration;
public class SimpleMOTD extends JavaPlugin {
    public void onEnable() {
        // Save a copy of the default config.yml if one is not there
        // Register a new listener
        getServer().getPluginManager().registerEvents(new Listener() {
            public void playerJoin(PlayerJoinEvent event) {
                // On player join send them the message from config.yml
        }, this);
        // Set the command executor for the rules command
        this.getCommand("rules").setExecutor(new CommandExecutor() {
            public boolean onCommand(CommandSender sender, Command command, String label, String[] args) {
                // On command send the rules from config.yml to the sender of the command
                List<String> rules = this.getConfig().getStringList("rules");
                for (String s : rules)
                return true;
The default config.yml that is in the plugin's jar
# default config.yml
message: Hello World and Welcome! :)
  - Play Nice
  - Respect others
  - Have Fun
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