What is simplest way to read a file into String? Do you want to read a plain text file in Java? How do you want to convert a File object to a String object? There are multiple ways we can read a file and covert it to String.
There are 5 total ways to convert whole text file to a String in Java.
- Files.readString()
- Files.readAllLines(Paths.get(path), StandardCharsets.UTF_8);
- FileUtils.readFileToString(new File(path), StandardCharsets.UTF_8); – Apache Commons IO Dependency
- Files.lines()
- Files.newBufferedReader()
Let’s get started:
- Make sure to add below Apache Commons IO dependency.
<dependency>
<groupId>commons-io</groupId>
<artifactId>commons-io</artifactId>
<version>2.11.0</version>
</dependency>
- Create class CrunchifyConvertFileToString.java.
- Copy and paste below code into it.
CrunchifyConvertFileToString.java
package crunchify.com.java.tutorials;
import org.apache.commons.io.FileUtils;
import java.io.File;
import java.io.IOException;
import java.nio.charset.StandardCharsets;
import java.nio.file.Files;
import java.nio.file.Paths;
import java.util.List;
/**
* @author Crunchify.com
* Program: In Java How to Read a File and Convert File to String? (5 different ways)
*/
public class CrunchifyConvertFileToString {
public static void main(String[] args) {
// Files.readString()
crunchifyFilesReadString();
// Files.readAllLines(Paths.get();
crunchifyFilesReadAllLines();
// FileUtils.readFileToString(new File();
// Apache Commons IO method
crunchifyFileUtilsReadFileToString();
// Files.lines()
// Please visit: https://crunchify.com/how-to-read-a-file-line-by-line-using-java-8-stream-files-lines-and-files-newbufferedreader-utils/
crunchifyFilesLines();
// Files.newBufferedReader()
// Please visit: https://crunchify.com/how-to-read-a-file-line-by-line-using-java-8-stream-files-lines-and-files-newbufferedreader-utils/
crunchifyFilesNewBufferedReader();
}
/*
Method-1: Files.readString()
*/
private static void crunchifyFilesReadString() {
String crunchifyFilePath = "/Users/app/Downloads/crunchify-file-to-string.txt";
try {
crunchifyLog("\n================= Files.readString() =================");
// Files: This class consists exclusively of static methods that operate on files, directories, or other types of files.
// Paths: This class consists exclusively of static methods that return a Path by converting a path string or URI.
// get(): Converts a path string, or a sequence of strings that when joined form a path string, to a Path.
String crunchifyFileData = Files.readString(Paths.get(crunchifyFilePath));
crunchifyLog(crunchifyFileData);
} catch (IOException exception) {
exception.printStackTrace();
}
}
/*
Simple Logging Utility
*/
private static void crunchifyLog(Object crunchifyFileData) {
System.out.println(crunchifyFileData);
}
/*
Method-2: Files.readAllLines(Paths.get();
*/
private static void crunchifyFilesReadAllLines() {
crunchifyLog("================= Files.readAllLines() =================");
String crunchifyFilePath = "/Users/app/Downloads/crunchify-file-to-string.txt";
try {
// readAllLines(): Read all lines from a file. This method ensures that the file is closed when
// all bytes have been read or an I/O error, or other runtime exception, is thrown.
// Bytes from the file are decoded into characters using the specified charset.
// This method recognizes the following as line terminators:
/* \u000D followed by \u000A, CARRIAGE RETURN followed by LINE FEED
\u000A, LINE FEED
\u000D, CARRIAGE RETURN
*/
List<String> crunchifyFileData = Files.readAllLines(Paths.get(crunchifyFilePath), StandardCharsets.UTF_8);
crunchifyLog(crunchifyFileData);
} catch (IOException exception) {
exception.printStackTrace();
}
}
/*
Method-3: FileUtils.readFileToString(new File();
Apache Commons IO: <dependency><groupId>commons-io</groupId><artifactId>commons-io</artifactId><version>2.6</version></dependency>
*/
private static void crunchifyFileUtilsReadFileToString() {
crunchifyLog("\n================= FileUtils.readFileToString() =================");
String crunchifyFilePath = "/Users/app/Downloads/crunchify-file-to-string.txt";
try {
// readFileToString: Reads the contents of a file into a String. The file is always closed.
String crunchifyFileData = FileUtils.readFileToString(new File(crunchifyFilePath), StandardCharsets.UTF_8);
// UTF_8: Eight-bit UCS Transformation Format.
crunchifyLog(crunchifyFileData);
} catch (IOException exception) {
exception.printStackTrace();
}
}
/*
Method-4: Files.lines()
*/
private static void crunchifyFilesLines() {
// Please visit: https://crunchify.com/how-to-read-a-file-line-by-line-using-java-8-stream-files-lines-and-files-newbufferedreader-utils/
}
/*
Method-5: Files.newBufferedReader()
*/
private static void crunchifyFilesNewBufferedReader() {
// Please visit: https://crunchify.com/how-to-read-a-file-line-by-line-using-java-8-stream-files-lines-and-files-newbufferedreader-utils/
}
}
IntelliJ IDEA Console Result:
Just run above program as a Java Application you will see result as below.
================= Files.readString() ================= Five Ways to Read File and Convert it to String :) Files.readString() Files.readAllLines(Paths.get(path), StandardCharsets.UTF_8); FileUtils.readFileToString(new File(path), StandardCharsets.UTF_8); Files.lines() Files.newBufferedReader() ================= Files.readAllLines() ================= [Five Ways to Read File and Convert it to String :), , Files.readString(), Files.readAllLines(Paths.get(path), StandardCharsets.UTF_8);, FileUtils.readFileToString(new File(path), StandardCharsets.UTF_8);, Files.lines(), Files.newBufferedReader()] ================= FileUtils.readFileToString() ================= Five Ways to Read File and Convert it to String :) Files.readString() Files.readAllLines(Paths.get(path), StandardCharsets.UTF_8); FileUtils.readFileToString(new File(path), StandardCharsets.UTF_8); Files.lines() Files.newBufferedReader() Process finished with exit code 0
Let me know if you face any issue running above code.
Here a tutorial which explains method4 and method-5: