Type inference

Type inference lets the Java compiler figure out generic types for you, so you don’t have to write them out every time. It makes code shorter and cleaner.

Example Without Type Inference

List<String> list = new ArrayList<String>();Code language: JavaScript (javascript)

With type inference (Java 7+):

List<String> list = new ArrayList<>();Code language: PHP (php)

The <> is called the diamond operator, and the compiler understands the type from the left-hand side.

Type Inference in Methods

You don’t have to specify types when calling generic methods — the compiler infers them

public static <T> T pick(T a, T b) {
    return a;
}

String result = pick("Java", "Generics"); // Inferred as <String>
Integer number = pick(1, 2);              // Inferred as <Integer>Code language: JavaScript (javascript)

Works with Lambdas and Streams (Java 8+)

List<String> names = List.of("LotusJavaPrince", "Mahesh");

names.forEach(name -> System.out.println(name)); // 'name' is inferred as StringCode language: PHP (php)

Custom Method with Type Inference

public static <K, V> Map<K, V> createMap(K key, V value) {
    Map<K, V> map = new HashMap<>();
    map.put(key, value);
    return map;
}

// Usage
Map<Integer, String> map = createMap(1, "Mahesh"); // Compiler infers typesCode language: JavaScript (javascript)

Type inference makes your code shorter and easier to read. But remember — the compiler needs enough information to guess the types correctly.