Java Convert File to String

In Java, we have many ways to convert a File to a String.

A text file for testing later.

1. Java 11 – Files.readString

A new method Files.readString is added in java.nio.file.Files, it makes reading a string from File much easier.

package com.mkyong;
import java.io.IOException;
import java.nio.file.Files;
import java.nio.file.Paths;
public class FileToString1 {
    public static void main(String[] args) {
        String path = "c:\\projects\\app.log";
        try {
            // default StandardCharsets.UTF_8
            String content = Files.readString(Paths.get(path));
            System.out.println(content);
        } catch (IOException e) {
            e.printStackTrace();

2. Java 8 – Files.lines

Convert a File into a Stream and join it.

package com.mkyong;
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 FileToString2 {
    public static void main(String[] args) {
        String path = "c:\\projects\\app.log";
        try (Stream<String> lines = Files.lines(Paths.get(path))) {
            // Formatting like \r\n will be lost
            // String content = lines.collect(Collectors.joining());
            // UNIX \n, WIndows \r\n
            String content = lines.collect(Collectors.joining(System.lineSeparator()));
            System.out.println(content);
			// File to List
            //List<String> list = lines.collect(Collectors.toList());
        } catch (IOException e) {
            e.printStackTrace();

3. Java 7 – Files.readAllLines

Convert a File into a List

package com.mkyong;
import java.io.IOException;
import java.nio.charset.StandardCharsets;
import java.nio.file.Files;
import java.nio.file.Paths;
import java.util.List;
public class FileToString3 {
    public static void main(String[] args) {
        String path = "c:\\projects\\app.log";
        try {
            // default StandardCharsets.UTF_8
            // Java 8
            // List<String> content = Files.readAllLines(Paths.get(path));
			// Java 7
            List<String> content = Files.readAllLines(Paths.get(path), StandardCharsets.UTF_8);
            System.out.println(content);
        } catch (IOException e) {
            e.printStackTrace();

Output

[A, B, C, D, E]

4. Apache Commons IO

	<dependency>
		<groupId>commons-io</groupId>
		<artifactId>commons-io</artifactId>
		<version>2.6</version>
	</dependency>

package com.mkyong;
import org.apache.commons.io.FileUtils;
import java.io.File;
import java.io.IOException;
import java.nio.charset.StandardCharsets;
public class FileToString4 {
    public static void main(String[] args) {
        String path = "c:\\projects\\app.log";
        try {
            String content = FileUtils.readFileToString(new File(path), StandardCharsets.UTF_8);
            System.out.println(content);
        } catch (IOException e) {
            e.printStackTrace();

Output