Java LongStream boxed() Method

The boxed() method in Java, part of the java.util.stream.LongStream interface, is used to convert a primitive LongStream into a Stream<Long>. This method is useful when you need to work with streams of objects rather than primitive values, allowing you to use object-specific methods and collections.

Table of Contents

1. Introduction
2. boxed() Method Syntax
3. Understanding boxed()
4. Examples
   • Basic Usage
   • Using boxed() in Combination with Other Stream Operations
5. Real-World Use Case
6. Conclusion

Introduction

The boxed() method converts each element of a LongStream into its corresponding Long object. This is particularly useful when you need to collect the elements into a collection that works with objects, such as a List<Long>.

boxed() Method Syntax

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

Stream<Long> boxed()

Parameters:

• This method does not take any parameters.

Returns:

• A Stream<Long> consisting of the elements of the original LongStream, each boxed to a Long object.

Throws:

• This method does not throw any exceptions.

Understanding boxed()

The boxed() method converts each element of the primitive LongStream to its corresponding Long object, effectively transforming a stream of primitive long values into a stream of Long objects. This conversion is necessary when you need to use object-specific methods or work with APIs that expect objects rather than primitives.

Examples

Basic Usage

To demonstrate the basic usage of boxed(), we will create a LongStream and convert it to a Stream<Long>.

Example

import java.util.stream.LongStream;
import java.util.stream.Stream;

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

        // Use boxed() to convert the LongStream to a Stream<Long>
        Stream<Long> boxedStream = longStream.boxed();

        // Print the elements of the Stream<Long>
        boxedStream.forEach(System.out::println);
    }
}

Output:

1
2
3
4
5

Using boxed() in Combination with Other Stream Operations

This example shows how to use boxed() in combination with other stream operations, such as collecting the elements into a list.

Example

import java.util.List;
import java.util.stream.Collectors;
import java.util.stream.LongStream;

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

        // Use boxed() to convert the LongStream to a Stream<Long> and collect it into a List<Long>
        List<Long> list = longStream.boxed().collect(Collectors.toList());

        // Print the elements of the list
        list.forEach(System.out::println);
    }
}

Output:

10
20
30
40
50

Real-World Use Case

Storing Long Values in a List

In real-world applications, the boxed() method can be used to store long values in a list for further processing, such as saving transaction amounts in a list.

Example

import java.util.List;
import java.util.stream.Collectors;
import java.util.stream.LongStream;

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

        // Use boxed() to convert the LongStream to a Stream<Long> and collect it into a List<Long>
        List<Long> transactions = transactionAmounts.boxed().collect(Collectors.toList());

        // Print the elements of the list
        transactions.forEach(System.out::println);
    }
}

Output:

1000
2000
1500
3000
2500

Conclusion

The LongStream.boxed() method is used to convert a primitive LongStream into a Stream<Long>. This method is particularly useful for working with streams of objects rather than primitive values, allowing you to use object-specific methods and collections. By understanding and using this method, you can efficiently manage and process streams of values in your Java applications, ensuring compatibility with APIs and collections that expect objects.