Java IntStream concat() Method

The concat() method in Java, part of the java.util.stream.IntStream interface, is used to concatenate two IntStream instances. This method is useful when you need to combine multiple streams into a single stream.

Table of Contents

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

Introduction

The concat() method returns a concatenated stream consisting of all elements of the first stream, followed by all elements of the second stream. This method is a static method and is particularly useful for combining streams.

concat() Method Syntax

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

static IntStream concat(IntStream a, IntStream b)

Parameters:

• a: The first IntStream.
• b: The second IntStream.

Returns:

• A new IntStream consisting of all elements of the first stream, followed by all elements of the second stream.

Throws:

• This method does not throw any exceptions.

Understanding concat()

The concat() method allows you to combine two IntStream instances into a single stream. The elements of the first stream are followed by the elements of the second stream, preserving the order of elements in each stream.

Examples

Basic Usage

To demonstrate the basic usage of concat(), we will create two IntStream instances and use concat() to combine them into a single stream.

Example

import java.util.stream.IntStream;

public class ConcatExample {
    public static void main(String[] args) {
        IntStream firstStream = IntStream.of(1, 2, 3);
        IntStream secondStream = IntStream.of(4, 5, 6);

        // Concatenate the two streams
        IntStream concatenatedStream = IntStream.concat(firstStream, secondStream);

        // Print the elements of the concatenated stream
        concatenatedStream.forEach(System.out::println);
    }
}

Output:

1
2
3
4
5
6

Using concat() with Other Stream Operations

This example shows how to use concat() in combination with other stream operations, such as filtering and mapping.

Example

import java.util.stream.IntStream;

public class ConcatWithOtherOperationsExample {
    public static void main(String[] args) {
        IntStream firstStream = IntStream.of(1, 2, 3);
        IntStream secondStream = IntStream.of(4, 5, 6);

        // Concatenate the two streams, filter, and map the elements
        IntStream processedStream = IntStream.concat(firstStream, secondStream)
                                             .filter(n -> n % 2 == 0)
                                             .map(n -> n * 10);

        // Print the processed elements
        processedStream.forEach(System.out::println);
    }
}

Output:

20
40
60

Real-World Use Case

Combining Data from Multiple Sources

In real-world applications, the concat() method can be used to combine data from multiple sources into a single stream for further processing.

Example

import java.util.stream.IntStream;

public class CombineDataSourcesExample {
    public static void main(String[] args) {
        IntStream dataSource1 = IntStream.of(10, 20, 30);
        IntStream dataSource2 = IntStream.of(40, 50, 60);

        // Combine the data from the two sources
        IntStream combinedStream = IntStream.concat(dataSource1, dataSource2);

        // Process the combined data
        combinedStream.forEach(System.out::println);
    }
}

Output:

10
20
30
40
50
60

Conclusion

The IntStream.concat() method is used to concatenate two IntStream instances into a single stream. This method is particularly useful for combining multiple streams into one for further processing. By understanding and using this method, you can efficiently manage and process streams of integer values in your Java applications.