Java 8 - Type inference and target typing

Category : Java | Sub Category : Java8 Features | By Prasad Bonam Last updated: 2023-11-13 04:25:37 Viewed : 233

Type inference and target typing are concepts in programming languages that relate to the ability of the compiler to deduce or infer types based on context, reducing the need for explicit type annotations in the code. These concepts play a significant role in languages that support features like lambda expressions, generics, and other advanced type systems.

Type Inference:

Type inference refers to the ability of a programming languages compiler to automatically deduce the data type of an expression or variable without explicit type annotations. This allows developers to write more concise code without sacrificing type safety.

In Java 8, type inference is closely associated with lambda expressions. When you use a lambda expression, the compiler can often infer the types of the parameters based on the context in which the lambda is used. For example:

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// Explicitly specifying types
BinaryOperator<Integer> add = (Integer x, Integer y) -> x + y;

// Type inference
BinaryOperator<Integer> addInferred = (x, y) -> x + y;

In the second example, the compiler infers the types of x and y based on the type of the BinaryOperator<Integer> interface to which the lambda expression is assigned.

Target Typing:

Target typing is a related concept that involves the compiler determining the expected type of an expression based on the context in which it is used. This is particularly relevant when working with lambda expressions, method references, and other instances where a functional interface is expected.

Consider the following example:

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// Using lambda expression
BinaryOperator<Integer> add = (x, y) -> x + y;

// Using method reference
BinaryOperator<Integer> addReference = Integer::sum;

In both cases, the compiler infers the expected type (BinaryOperator<Integer>) based on the context in which the lambda expression or method reference is used. This context-driven type inference is an example of target typing.

Both type inference and target typing contribute to the expressiveness and conciseness of code, particularly when working with features introduced in Java 8, such as lambda expressions and the Stream API. They allow developers to write code that is more readable and requires fewer explicit type annotations while still maintaining type safety.