String lines() – Get stream of lines in Java

Learn to convert multi-line string into stream of lines using String.lines() method in Java 11. This method is useful when we want to read content from a file and process each string separately.

1. String.lines() API

This is a static method. This method returns a stream of lines extracted from a given multi-line string, separated by line terminators.

/**
* returns - the stream of lines extracted from given string
*/
public Stream<String> lines()

A line terminator is one of the following –

• a line feed character (“\n”)
• a carriage return character (“\r”)
• a carriage return followed immediately by a line feed (“\r\n”)

By definition, a line is zero or more character followed by a line terminator. A line does not include the line terminator.

The stream returned by this method contains the lines from this string in the order in which they occur.

2. Convert String to Stream of Lines Example

Java program to read a file and get the content as stream of lines.

import java.io.IOException;
import java.nio.file.Files;
import java.nio.file.Path;
import java.nio.file.StandardOpenOption;
import java.util.stream.Stream;

public class Main 
{
	public static void main(String[] args) 
	{
		try 
		{
			Path file = Files.createTempFile("testOne", ".txt");

			//Write contents to file
			Files.writeString(file, "ABC\n", StandardOpenOption.APPEND);
			Files.writeString(file, "123\n", StandardOpenOption.APPEND);
			Files.writeString(file, "XYZ", StandardOpenOption.APPEND);	

			Stream<String> lines = Files.lines(file);

			lines.forEach(System.out::println);
		} 
		catch (IOException e) 
		{
			e.printStackTrace();
		}
	}
}

Program output.

ABC
123
XYZ

Drop me your questions related to reading a file into lines of stream.

Happy Learning !!

Ref: Java docs