Java Files mismatch()

In this guide, you will learn about the Files mismatch() method in Java programming and how to use it with an example.

1. Files mismatch() Method Overview

Definition:

The mismatch(Path path1, Path path2) method is a part of the Files class in Java. This method is used to find and return the position of the first mismatched byte in the content of two files, which is useful for comparing file contents.

Syntax:

long mismatch(Path path1, Path path2) throws IOException

Parameters:

- path1: The first path to the file to be compared.

- path2: The second path to the file to be compared.

Key Points:

- The method returns the position of the first mismatched byte in the file content, or -1L if there is no mismatch.

- It considers the end of the file (EOF) as a mismatch.

- This method is suitable for comparing reasonably small files.

- It throws IOException if an I/O error occurs.

2. Files mismatch() Method Example

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

public class MismatchExample {
    public static void main(String[] args) {
        Path path1 = Paths.get("path/to/file1.txt");
        Path path2 = Paths.get("path/to/file2.txt");

        try {
            long mismatchPosition = Files.mismatch(path1, path2);
            if (mismatchPosition == -1L) {
                System.out.println("Both files have the same content.");
            } else {
                System.out.println("The files have a mismatch at byte position: " + mismatchPosition);
            }
        } catch (IOException e) {
            e.printStackTrace();
        }
    }
}

Output:

The files have a mismatch at byte position: 5

Explanation:

In this example, we have two Path objects pointing to different file paths. 

We then use the Files.mismatch() method to find the position of the first mismatched byte between the file contents. The method returns the byte position of the first mismatch, and the output reflects this position. If the files have the same content, it would return -1L, indicating no mismatch. Any I/O error occurring during the operation is caught and the stack trace is printed.