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
- Introduction
boxed()
Method Syntax- Understanding
boxed()
- Examples
- Basic Usage
- Using
boxed()
in Combination with Other Stream Operations
- Real-World Use Case
- 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 originalLongStream
, each boxed to aLong
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.