Read String line by line

Question

Given a string that isn\'t too long, what is the best way to read it line by line?

I know you can do:

BufferedReader reader = new BufferedReader(new          


        

Answer 1

You can try the following regular expression:

\r?\n

Code:

String input = "\nab\n\n    \n\ncd\nef\n\n\n\n\n";
String[] lines = input.split("\\r?\\n", -1);
int n = 1;
for(String line : lines) {
    System.out.printf("\tLine %02d \"%s\"%n", n++, line);
}

Output:

Line 01 ""
Line 02 "ab"
Line 03 ""
Line 04 "    "
Line 05 ""
Line 06 "cd"
Line 07 "ef"
Line 08 ""
Line 09 ""
Line 10 ""
Line 11 ""
Line 12 ""

Answer 2

You can use the stream api and a StringReader wrapped in a BufferedReader which got a lines() stream output in java 8:

import java.util.stream.*;
import java.io.*;
class test {
    public static void main(String... a) {
        String s = "this is a \nmultiline\rstring\r\nusing different newline styles";

        new BufferedReader(new StringReader(s)).lines().forEach(
            (line) -> System.out.println("one line of the string: " + line)
        );
    }
}

Gives

one line of the string: this is a
one line of the string: multiline
one line of the string: string
one line of the string: using different newline styles

Just like in BufferedReader's readLine, the newline character(s) themselves are not included. All kinds of newline separators are supported (in the same string even).

Answer 3

Since Java 11, there is a new method String.lines:

/**
 * Returns a stream of lines extracted from this string,
 * separated by line terminators.
 * ...
 */
public Stream<String> lines() { ... }

Usage:

"line1\nline2\nlines3"
    .lines()
    .forEach(System.out::println);

Answer 4

Using Apache Commons IOUtils you can do this nicely via

List<String> lines = IOUtils.readLines(new StringReader(string));

It's not doing anything clever, but it's nice and compact. It'll handle streams as well, and you can get a LineIterator too if you prefer.

Answer 5

There is also Scanner. You can use it just like the BufferedReader:

Scanner scanner = new Scanner(myString);
while (scanner.hasNextLine()) {
  String line = scanner.nextLine();
  // process the line
}
scanner.close();

I think that this is a bit cleaner approach that both of the suggested ones.