Java DoubleToIntFunction

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Introduction

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

Table of Contents

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

1. What is DoubleToIntFunction?

DoubleToIntFunction is a functional interface that takes a double as input and returns an int. It is useful for scenarios where you need to convert double values to int values, such as rounding or type conversion.

2. Methods and Syntax

The main method in the DoubleToIntFunction interface is:

• int applyAsInt(double value): Applies this function to the given argument and returns an int result.

Syntax

DoubleToIntFunction doubleToIntFunction = (double value) -> {
    // operation on value
    return result;
};

3. Examples of DoubleToIntFunction

Example 1: Rounding a Double to an Integer

import java.util.function.DoubleToIntFunction;

public class RoundingExample {
    public static void main(String[] args) {
        // Define a DoubleToIntFunction that rounds a double to an int
        DoubleToIntFunction roundToInt = (value) -> (int) Math.round(value);

        int result = roundToInt.applyAsInt(5.7);

        System.out.println("Rounded Value: " + result);
    }
}

Output:

Rounded Value: 6

Example 2: Converting Double to Integer by Truncation

import java.util.function.DoubleToIntFunction;

public class TruncateExample {
    public static void main(String[] args) {
        // Define a DoubleToIntFunction that truncates a double to an int
        DoubleToIntFunction truncateToInt = (value) -> (int) value;

        int result = truncateToInt.applyAsInt(9.8);

        System.out.println("Truncated Value: " + result);
    }
}

Output:

Truncated Value: 9

4. Real-World Use Case: Calculating Score from Ratings

In gaming or review applications, DoubleToIntFunction can be used to convert a rating to a score out of 10.

import java.util.function.DoubleToIntFunction;

public class RatingToScore {
    public static void main(String[] args) {
        // Define a DoubleToIntFunction to convert a rating to a score
        DoubleToIntFunction ratingToScore = (rating) -> (int) (rating * 2);

        int score = ratingToScore.applyAsInt(4.5);

        System.out.println("Score: " + score);
    }
}

Output:

Score: 9

Conclusion

The DoubleToIntFunction interface is a practical tool in Java for converting double values to int results. It is especially useful in applications requiring type conversion or mathematical processing. Using DoubleToIntFunction can lead to cleaner and more efficient code, particularly in functional programming contexts.