How to Efficiently Create a String from a File in Java?

What are the best methods to create a Java string from the contents of a file?

private String readFile(String filePath) throws IOException {
    return Files.readString(Path.of(filePath));
}

Reading the contents of a file into a String in Java can be done using various methods. Below, we explore some popular approaches, including reading line by line and utilizing Java NIO, along with a discussion of the benefits and drawbacks of each method.

import java.nio.file.Files;
import java.nio.file.Path;
import java.io.IOException;

public class FileUtil {
    public static String readFile(String filePath) throws IOException {
        return Files.readString(Path.of(filePath));  
    }
}

Causes

• Using BufferedReader for line-by-line reading can be efficient for small files
• Java NIO provides a more concise and modern approach, especially for larger files

Solutions

• Use `java.nio.file.Files` for simple and effective file reading: `Files.readString(Path.of(filePath))`
• For legacy support and compatibility, continue using `BufferedReader`

Mistake: Not handling exceptions properly when reading files.

Solution: Always include proper exception handling using try-catch blocks.

Mistake: Forgetting to close file resources, leading to memory leaks.

Solution: Utilize try-with-resources statement to automatically close file streams.