What is FileUtils.contentEquals() in Java?

Overview

contentEquals() is a staticThis describes the methods in Java that can be called without creating an object of the class method of the FileUtils class that is used to check whether the contents of two files are equal.

This method first checks to see if the two files are different lengths or if they point to the same file before resorting to the byte-by-byte comparison of the file contents.

How to import FileUtils

The definition of FileUtils can be found in the Apache Commons IO package, which we can add to the Maven project by adding the following dependency to the pom.xml file:

<dependency>
            <groupId>commons-io</groupId>
            <artifactId>commons-io</artifactId>
            <version>2.11.0</version>
</dependency>

For other versions of the commons-io package, refer to the Maven Repository.

You can import the FileUtils class as follows:

import org.apache.commons.io.FileUtils;

Syntax

public static boolean contentEquals(final File file1, final File file2)

Parameters

  • final File file1: This is the first file.
  • final File file2: This is the second file.

Return value

This method returns true if the file contents are equal and returns false otherwise.

import org.apache.commons.io.FileUtils;
import java.io.BufferedReader;
import java.io.File;
import java.io.FileReader;
import java.io.IOException;
public class Main{
    private static void printFile(String filePath) throws IOException {
        BufferedReader bufferedReader
                = new BufferedReader(new FileReader(filePath));
        String string;
        while ((string = bufferedReader.readLine()) != null)
            System.out.println(string);
    }
    private static void wrapper(String path1, String path2) throws IOException {
        File file1 = new File(path1);
        File file2 = new File(path2);
        
        System.out.println("The contents of " + path1 + " is as follows:");
        printFile(path1);
        
        System.out.println("The contents of " + path2 + " is as follows:");
        printFile(path2);
        
        System.out.println("The output of FileUtils.contentEquals(file1, file2) - " + FileUtils.contentEquals(file1, file2));
    }
    public static void main(String[] args) throws IOException {
        // Example 1
        String filePath1 = "/Users/educative/Documents/temp/1.txt";
        String filePath2 = "/Users/educative/Documents/temp/2.txt";
        wrapper(filePath1, filePath2);
        System.out.println("-------");
        
        // Example 2
        wrapper(filePath1, filePath1);
        System.out.println("-------");
        
        // Example 3
        filePath2 = "/Users/educative/Documents/temp/3.txt";
        wrapper(filePath1, filePath2);
    }
}

Code

Example 1

  • File 1 - 1.txt
  • File 2 - 2.txt

The method returns true, indicating that the contents of both the files are equal.

Example 2

  • File 1 - 1.txt
  • File 2 - 1.txt

The method returns true, indicating that both of the files are the same.

Example 3

  • File 1 - 1.txt
  • File 2 - 3.txt

The method returns false, indicating that the contents of both the files are different.

Explanation

In the above code, we define two private methods. One is to print the file given the path to the file. The other method is a wrapper method that takes two file paths, calls the printFile(), and prints the output of the FileUtils.contentEquals() method.

We use three different files, i.e., 1.txt, 2.txt, and 3.txt. The contents of 1.txt and 2.txt are the same, but the content of 3.txt is different from the other two.

Output

The output of the code is as follows:

The contents of /Users/educative/Documents/temp/1.txt is as follows:
hello-educative
The contents of /Users/educative/Documents/temp/2.txt is as follows:
hello-educative
The output of FileUtils.contentEquals(file1, file2) - true
-------
The contents of /Users/educative/Documents/temp/1.txt is as follows:
hello-educative
The contents of /Users/educative/Documents/temp/1.txt is as follows:
hello-educative
The output of FileUtils.contentEquals(file1, file2) - true
-------
The contents of /Users/educative/Documents/temp/1.txt is as follows:
hello-educative
The contents of /Users/educative/Documents/temp/3.txt is as follows:
adfge
The output of FileUtils.contentEquals(file1, file2) - false

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