Java IntFunction

Introduction

In Java, the IntFunction interface is a functional interface that represents a function that accepts an int-valued argument and produces a result. It is part of the java.util.function package and is commonly used for operations that transform or process int values into other types.

Table of Contents

1. What is IntFunction?
2. Methods and Syntax
3. Examples of IntFunction
4. Real-World Use Case
5. Conclusion

1. What is IntFunction?

IntFunction is a functional interface that takes an int as input and returns a result of a specified type. It is useful for scenarios where int values need to be converted or processed into other forms.

2. Methods and Syntax

The main method in the IntFunction interface is:

• R apply(int value): Applies this function to the given argument and returns a result.

Syntax

IntFunction<R> intFunction = (int value) -> {
    // operation on value
    return result;
};

3. Examples of IntFunction

Example 1: Converting an Integer to a String

import java.util.function.IntFunction;

public class IntToStringExample {
    public static void main(String[] args) {
        // Define an IntFunction that converts an int to a string
        IntFunction<String> intToString = (value) -> "Number: " + value;

        String result = intToString.apply(10);
        System.out.println(result);
    }
}

Output:

Number: 10

Example 2: Calculating the Square of an Integer

import java.util.function.IntFunction;

public class SquareExample {
    public static void main(String[] args) {
        // Define an IntFunction that calculates the square of an int
        IntFunction<Integer> square = (value) -> value * value;

        int result = square.apply(4);
        System.out.println("Square: " + result);
    }
}

Output:

Square: 16

4. Real-World Use Case: Mapping Error Codes to Messages

In applications, IntFunction can be used to map error codes to descriptive messages.

import java.util.function.IntFunction;

public class ErrorCodeMapper {
    public static void main(String[] args) {
        // Define an IntFunction to map error codes to messages
        IntFunction<String> errorCodeToMessage = (code) -> {
            switch (code) {
                case 404: return "Not Found";
                case 500: return "Internal Server Error";
                default: return "Unknown Error";
            }
        };

        String message = errorCodeToMessage.apply(404);
        System.out.println("Error Message: " + message);
    }
}

Output:

Error Message: Not Found

Conclusion

The IntFunction interface is a practical tool in Java for transforming int values into other types. It is particularly useful in scenarios requiring data conversion or processing. Using IntFunction can lead to cleaner and more efficient code, especially in functional programming contexts.