Java Stream of() Method

The Stream.of() method in Java, part of the java.util.stream.Stream interface, is used to create a sequential Stream from a given set of values or from an array. This method is useful when you need to quickly create a stream from a known set of elements.

Table of Contents

1. Introduction
2. Stream.of() Method Syntax
3. Understanding Stream.of()
4. Examples
   • Creating a Stream from Individual Values
   • Creating a Stream from an Array
5. Real-World Use Case
6. Conclusion

Introduction

The Stream.of() method allows you to create a stream from a specified set of values or from an array. This method is particularly useful for quickly generating streams for processing.

Stream.of() Method Syntax

The syntax for the Stream.of() method is as follows:

@SafeVarargs
static <T> Stream<T> of(T... values)

Parameters:

• values: The elements to be included in the newly created stream.

Returns:

• A new sequential Stream containing the specified elements.

Throws:

• This method does not throw any exceptions.

Understanding Stream.of()

The Stream.of() method is a varargs method, which means you can pass any number of arguments to create a stream. Additionally, you can pass an array to the method to create a stream from its elements.

Examples

Creating a Stream from Individual Values

To demonstrate how to create a stream from individual values using Stream.of(), we will create a stream of strings.

Example

import java.util.stream.Stream;

public class StreamOfExample {
    public static void main(String[] args) {
        // Create a stream from individual values
        Stream<String> stream = Stream.of("apple", "banana", "cherry");

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

Output:

apple
banana
cherry

Creating a Stream from an Array

This example shows how to use Stream.of() to create a stream from an array of integers.

Example

import java.util.stream.Stream;

public class StreamOfArrayExample {
    public static void main(String[] args) {
        Integer[] numbers = {1, 2, 3, 4, 5};

        // Create a stream from an array
        Stream<Integer> stream = Stream.of(numbers);

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

Output:

1
2
3
4
5

Real-World Use Case

Creating a Stream of Configurations

In real-world applications, the Stream.of() method can be used to create a stream of configuration settings or parameters for processing.

Example

import java.util.stream.Stream;

public class StreamOfConfigExample {
    static class Config {
        String key;
        String value;

        Config(String key, String value) {
            this.key = key;
            this.value = value;
        }

        @Override
        public String toString() {
            return key + "=" + value;
        }
    }

    public static void main(String[] args) {
        Config[] configs = {
            new Config("url", "http://example.com"),
            new Config("timeout", "5000"),
            new Config("maxConnections", "100")
        };

        // Create a stream from an array of configurations
        Stream<Config> configStream = Stream.of(configs);

        // Print the configuration settings
        configStream.forEach(System.out::println);
    }
}

Output:

url=http://example.com
timeout=5000
maxConnections=100

Conclusion

The Stream.of() method is used to create a sequential Stream from a given set of values or from an array. This method is particularly useful for quickly generating streams for processing. By understanding and using this method, you can efficiently manage and process streams of values in your Java applications, ensuring flexibility and ease of use when working with known sets of elements.