toml4j

toml4j is a TOML 0.4.0 parser for Java.

Installation

Add the following dependency to your POM (or equivalent for other dependency managers):

<dependency>
  <groupId>dev.plex</groupId>
  <artifactId>toml4j</artifactId>
  <version>0.7.3</version>
</dependency>

If you use Gradle, you can use the following code:

repositories {
  mavenCentral()
  maven {
      url = uri("https://nexus.telesphoreo.me/repository/totalfreedom/")
  }
}

dependencies {
  ...
  implementation("dev.plex:toml4j:0.7.3")
}

Requires Java 17 above.

Quick start

Toml toml = new Toml().read(getTomlFile());
String someValue = toml.getString("someKey");
Date someDate = toml.getDate("someTable.someDate");
MyClass myClass = toml.to(MyClass.class);

Usage

A dev.plex.Toml instance is populated by calling one of read(File), read(InputStream), read(Reader), read(String) or read(Toml).

Toml toml = new Toml().read("a=1");

An exception is thrown if the source is not valid TOML.

The data can then be accessed either by converting the Toml instance to your own class or by accessing tables and keys by name.

Maps

Toml#toMap() is a quick way to turn a Toml instance into a Map<String, Object>.

Map<String, Object> map = new Toml().read("a=1").toMap();

Custom classes

Toml#to(Class<T>) maps a Toml instance to the given class.

name = "Mwanji Ezana"

[address]
  street = "123 A Street"
  city = "AnyVille"
  
[contacts]
  "email address" = "me@example.com"

class Address {
  String street;
  String city;
}

class User {
  String name;
  Address address;
  Map<String, Object> contacts;
}

User user = new Toml().read(tomlFile).to(User.class);

assert user.name.equals("Mwanji Ezana");
assert user.address.street.equals("123 A Street");
assert user.contacts.get("\"email address\"").equals("me@example.com");

Any keys not found in both the TOML and the class are ignored. Fields may be private.

Quoted keys cannot be mapped directly to a Java object, but they can be used as keys within a Map.

TOML primitives can be mapped to a number of Java types:

TOML	Java
Integer	int, long (or wrapper), java.math.BigInteger
Float	float, double (or wrapper), java.math.BigDecimal
String	String, enum, java.net.URI, java.net.URL
One-letter String	char, Character
Multiline and Literal Strings	String
Array	List, Set, array. The generic type can be anything that can be converted.
Table	Custom class, Map<String, Object>

Custom classes, Maps and collections thereof can be nested to any level. See TomlToClassTest#should_convert_fruit_table_array() for an example.

Key names

Use the getters to retrieve the data:

• getString(String)
• getDate(String)
• getBoolean(String)
• getLong(String)
• getDouble(String)
• getList(String)
• getTable(String) returns a new Toml instance containing only the keys in that table.
• getTables(String), for table arrays, returns List<Toml>.

You can also navigate values within a table with a compound key of the form table.key. Use a zero-based index such as tableArray[0].key to navigate table arrays.

Non-existent keys return null.

When retrieving quoted keys, the quotes must be used and the key must be spelled exactly the same way, including quotes and whitespace. The only exceptions are Unicode escapes: "\u00B1" = "value" would be retrieved with toml.getString("\"±\"").

title = "TOML Example"
"sub title" = "Now with quoted keys"

[database]
  ports = [ 8001, 8001, 8002 ]
  enabled = true
  [database.credentials]
    password = "password"
    
[servers]
  cluster = "hyades"
  [servers.alpha]
  ip = "10.0.0.1"
  
[[networks]]
  name = "Level 1"
  [networks.status]
    bandwidth = 10

[[networks]]
  name = "Level 2"

[[networks]]
  name = "Level 3"
  [[networks.operators]]
    location = "Geneva"
  [[networks.operators]]
    location = "Paris"

Toml toml = new Toml().read(getTomlFile());

String title = toml.getString("title");
String subTitle = toml.getString("\"sub title\"");
Boolean enabled = toml.getBoolean("database.enabled");
List<Long> ports = toml.getList("database.ports");
String password = toml.getString("database.credentials.password");

Toml servers = toml.getTable("servers");
String cluster = servers.getString("cluster"); // navigation is relative to current Toml instance
String ip = servers.getString("alpha.ip");

Toml network1 = toml.getTable("networks[0]");
String network2Name = toml.getString("networks[1].name"); // "Level 2"
List<Toml> network3Operators = toml.getTables("networks[2].operators");
String network3Operator2Location = toml.getString("networks[2].operators[1].location"); // "Paris"

Defaults

The constructor can be given a set of default values that will be used as fallbacks. For tables and table arrays, a shallow merge is performed.

Toml#read(Toml) is used to merge two Toml instances:

Toml toml1 = new Toml().read("a=1");
Toml toml2 = new Toml().read(getTomlFile());

Toml mergedToml = new Toml(toml1).read(toml2);

You can also call an overloaded version of the getters that take a default value. Note that the default value provided in the constructor take precedence over the one provided by the getter.

# defaults
a = 2
b = 3

[table]
  c = 4
  d = 5

a = 1

[table]
  c = 2
  
[[array]]
  d = 3

Toml defaults = new Toml().read(getDefaultsFile());
Toml toml = new Toml(defaults).read(getTomlFile());

Long a = toml.getLong("a"); // returns 1, not 2
Long b = toml.getLong("b"); // returns 3, taken from defaults provided to constructor
Long bPrefersConstructor = toml.getLong("b", 5); // returns 3, not 5
Long c = toml.getLong("c"); // returns null
Long cWithDefault = toml.getLong("c", 5); // returns 5
Long tableC = toml.getLong("table.c"); // returns 2, not 4
Long tableD = toml.getLong("table.d"); // returns null, not 5, because of shallow merge
Long arrayD = toml.getLong("array[0].d"); // returns 3

Reflection

Toml#entrySet() returns a Set of Map.Entry instances. Modifications to the returned Set are not reflected in the Toml instance. Note that Map.Entry#setValue() will throw an UnsupportedOperationException.

for (Map.Entry<String, Object> entry : myToml.entrySet()) {
  System.out.println(entry.getKey() + " " + entry.getValue());
}

Toml#contains(String) verifies that the instance contains a key of any type (primitive, table or array of tables) of the given name. Toml#containsPrimitive(String), Toml#containsTable(String) and Toml#containsTableArray(String) return true only if a key exists and is a primitive, table or array of tables, respectively. Compound keys can be used to check existence at any depth.

Toml toml = new Toml().read("a = 1");

toml.contains("a"); // true
toml.conatinsKey("a"); // true
toml.containsTable("a"); // false
toml.containsTableArray("a"); // false

Converting Objects To TOML

You can write Maps and custom objects to a TOML String, File, Writer, or OutputStream with a TomlWriter. Each TomlWriter instance is customisable, immutable and threadsafe, so it can be reused and passed around. Constants and transient fields are ignored.

To write a List of objects as a table array, put the list in a Map or in a custom object.

class AClass {
  int anInt = 1;
  int[] anArray = { 2, 3 };
}

TomlWriter tomlWriter = new TomlWriter();
AClass obj = new AClass();

Map<String, Object> map = new HashMap<String, Object>();
int[] intArray = { 2, 3 };
map.put("anInt", 1);
map.put("anArray", intArray);

String tomlString = tomlWriter.write(obj);
tomlString = tomlWriter.write(map);

tomlWriter.write(obj, new File("path/to/file"));
tomlWriter.write(obj, new ByteArrayOutputStream());
tomlWriter.write(obj, new OutputStreamWriter(anOutputStream));

/*
All methods output:

anInt = 1
anArray = [2, 3]
*/

You can customise formatting with a TomlWriter.Builder:

class BClass {
 Map<String, ?> aMap = new HashMap<String, Object>();
}

BClass obj = new BClass();
obj.aMap.put("item", 1);

TomlWriter tomlWriter = new TomlWriter.Builder()
 .indentValuesBy(2)
 .indentTablesBy(4)
 .padArrayDelimitersBy(3)
 .build();
   
String tomlString = tomlWriter.write(obj);

/*
Output:

[aMap]
 item = 1
 
   [aMap.a]
     anInt = 1
     anArray = [   2, 3   ]
*/

Threadsafety

TomlWriter is threadsafe, however the JDK's streams and Writer are not. Take care not to write to the same stream in parallel.

Limitations

Date precision is limited to milliseconds.

Changelog

Please see the changelog.

Contributing

Please see the contribution guidelines.

License

toml4j is copyright (c) 2013-2015 Moandji Ezana and is licensed under the MIT License