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Higher-Order Methods in Java

Higher-Order Methods in Java are methods that accept behavior as a parameter or return behavior, often enabled by [[Functional Interfaces]] and Lambda expressions. This approach treats logic as a value, allowing actions or methods to be passed around just like data^[600-developer-java-java8-java8-lambda.md].

Core Concept

The concept is often compared to callback functions in JavaScript (e.g., passing a function callback to execute logic inside another function)^[600-developer-java-java8-java8-lambda.md]. In Java, this is achieved by passing functional interfaces as parameters, effectively allowing developers to "pass actions" or "pass methods"^[600-developer-java-java8-java8-lambda.md].

For example, a method can take a java.util.Function<Integer, Integer> as an argument to apply a specific operation (like multiplication or addition) dynamically^[600-developer-java-java8-java8-lambda.md].

Standard Functional Interfaces

Java provides several Built-in Functional Interfaces (located in java.util.function) to support higher-order programming^[600-developer-java-java8-java8-lambda.md]:

  • Function<T, R>: Represents a unary function from argument T to return type R^[600-developer-java-java8-java8-lambda.md].
  • Consumer<T>: Represents a unary function from T to void (an operation that accepts an argument but returns no result)^[600-developer-java-java8-java8-lambda.md].
  • Predicate<T>: Represents a unary function from T to boolean (often used for filtering or testing conditions)^[600-developer-java-java8-java8-lambda.md].
  • Supplier<T>: Represents a nilary function (no arguments) that returns a result of type R^[600-developer-java-java8-java8-lambda.md].

Sources

  • 600-developer-java-java8-java8-lambda.md