How to iterate over Java 8 String Stream and append line to String?

user_3260912 0
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I have a method using the code below based on other resources how to iterate a file using a Java 8 stream:


String result = "";

try (Stream<String> stream = Files.lines(Paths.get("/home/user/file.txt"))) {
   stream.forEach(System.out::println);
} catch (IOException e) {
   e.printStackTrace();
}

However, I want to save the lines to += a string, instead of console.

I have tried these 2 below but neither pass IDE validation:

stream.forEach(thisString -> result += thisString);

stream.forEach(result += this);

stream.forEach(result::this);

What is the proper way to append each result from the foreach loop to a String object?

java-stream java-8 java
2 Answers

If you just want to read the whole file as String, there is no need to use a Stream. If you are using Java 11, you can just use Files.readString():

try {
    String result = Files.readString(Paths.get("/home/user/file.txt"));
    System.out.println(result);
} catch (IOException e) {
    e.printStackTrace();
}

If you need a Java 8 solution, see Holger's comment.

user_96626010

Hadi J has given you the answer in his comment

import java.io.IOException;
import java.nio.file.Files;
import java.nio.file.Paths;
import java.util.stream.Collectors;
import java.util.stream.Stream;

public class FileJoin {

    public static void main(String[] args) {
        String result = "";

        try (Stream<String> stream = Files.lines(Paths.get("/home/user/file.txt"))) {
           result = stream.collect(Collectors.joining());
        } catch (IOException e) {
           e.printStackTrace();
        }
        System.out.println(result);
    }
}
user_21643650
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