Java LongStream toArray() Method

The toArray() method in Java, part of the java.util.stream.LongStream interface, is used to accumulate the elements of the stream into a new array. This method is useful when you need to convert a stream of long values into an array.

Table of Contents

1. Introduction
2. toArray() Method Syntax
3. Understanding toArray()
4. Examples
   • Basic Usage
   • Using toArray() with Filtering and Mapping
5. Real-World Use Case
6. Conclusion

Introduction

The toArray() method is a terminal operation that returns an array containing the elements of the stream. This is particularly useful when you need to perform operations on the stream elements in an array form or when you need to pass the elements to a method that requires an array.

toArray() Method Syntax

The syntax for the toArray() method is as follows:

long[] toArray()

Parameters:

• This method does not take any parameters.

Returns:

• An array containing the elements of the stream.

Throws:

• This method does not throw any exceptions.

Understanding toArray()

The toArray() method processes the elements of the stream and collects them into a new array. Since it is a terminal operation, it consumes the stream and returns an array containing the elements of the stream.

Examples

Basic Usage

To demonstrate the basic usage of toArray(), we will create a LongStream and use toArray() to convert its elements into an array.

Example

import java.util.Arrays;
import java.util.stream.LongStream;

public class ToArrayExample {
    public static void main(String[] args) {
        LongStream stream = LongStream.of(1L, 2L, 3L, 4L, 5L);

        // Use toArray() to convert the stream to an array
        long[] array = stream.toArray();

        // Print the array
        System.out.println(Arrays.toString(array));
    }
}

Output:

[1, 2, 3, 4, 5]

Using toArray() with Filtering and Mapping

This example shows how to use toArray() in combination with filtering and mapping operations.

Example

import java.util.Arrays;
import java.util.stream.LongStream;

public class ToArrayWithFilterAndMapExample {
    public static void main(String[] args) {
        LongStream stream = LongStream.of(10L, 20L, 30L, 40L, 50L);

        // Use toArray() to convert the filtered and mapped stream to an array
        long[] array = stream
            .filter(n -> n > 25)  // Keep elements greater than 25
            .map(n -> n / 10)     // Divide each element by 10
            .toArray();

        // Print the array
        System.out.println(Arrays.toString(array));
    }
}

Output:

[3, 4, 5]

Real-World Use Case

Converting Transaction Amounts to an Array

In real-world applications, the toArray() method can be used to convert a stream of transaction amounts into an array for further processing or analysis.

Example

import java.util.Arrays;
import java.util.stream.LongStream;

public class ToArrayTransactionsExample {
    public static void main(String[] args) {
        LongStream transactionAmounts = LongStream.of(1000L, 2000L, 1500L, 3000L, 2500L);

        // Use toArray() to convert the transaction amounts to an array
        long[] transactionArray = transactionAmounts.toArray();

        // Print the transaction amounts array
        System.out.println("Transaction Amounts: " + Arrays.toString(transactionArray));
    }
}

Output:

Transaction Amounts: [1000, 2000, 1500, 3000, 2500]

Conclusion

The LongStream.toArray() method is used to accumulate the elements of the stream into a new array. This method is particularly useful for converting a stream of long values into an array for further processing or analysis. By understanding and using this method, you can efficiently manage and process streams of values in your Java applications, ensuring that elements are collected into an array as needed.