DigestInputStream getMessageDigest() method in Java with Examples

The getMessageDigest() method of java.security.DigestInputStream class provides the MessageDigest assigned to this DigestInputStream object.

Syntax:

public MessageDigest getMessageDigest()

Return Value: This method returns MessageDigest object assigned to it.

Note: All the programs in this article won’t run on online IDE as no ‘name’ file exists. You can check this code on Java compiler on your system. To check this code, create a file ‘name’ on your system.

Below are the examples to illustrate the getMessageDigest() method:

Example 1:

Java

// Java program to demonstrate
// getMessageDigest() method

import java.security.*;
import java.util.*;
import java.io.*;

public class GFG {
    public static void main(String[] argv)
    {
        try {
            // creating the object of MessageDigest
            // and getting instance
            // By using getInstance() method
            MessageDigest sr
                = MessageDigest.getInstance("MD5");

            // creating and initializing
            // object of InputStream
            InputStream is
                = new FileInputStream("f:/java/name.txt");

            // creating and initializing
            // object of DigestInputStream
            DigestInputStream di
                = new DigestInputStream(is, sr);

            // getting the message digest
            // using getMessageDigest() method
            MessageDigest str = di.getMessageDigest();

            // display the result
            System.out.println("Status : " + str.toString());
        }

        catch (NoSuchAlgorithmException e) {

            System.out.println("Exception thrown : " + e);
        }
        catch (NullPointerException e) {

            System.out.println("Exception thrown : " + e);
        }
        catch (FileNotFoundException e) {

            System.out.println("Exception thrown : " + e);
        }
    }
}

Output:

Status : MD5 Message Digest from SUN, 

Example 2:

Java

// Java program to demonstrate
// getMessageDigest() method

import java.security.*;
import java.util.*;
import java.io.*;

public class GFG {
    public static void main(String[] argv)
    {
        try {
            // creating the object of MessageDigest
            // and getting instance
            // By using getInstance() method
            MessageDigest sr
                = MessageDigest.getInstance("SHA-1");

            // creating and initializing
            // object of InputStream
            InputStream is
                = new FileInputStream("f:/java/name.txt");

            // creating and initializing// object of DigestInputStream
                DigestInputStream di
                = new DigestInputStream(is, sr);

            // getting the message digest
            // using getMessageDigest() method
            MessageDigest str = di.getMessageDigest();

            // printing the status
            System.out.println("Status : " + str.toString());
        }

        catch (NoSuchAlgorithmException e) {

            System.out.println("Exception thrown : " + e);
        }
        catch (NullPointerException e) {

            System.out.println("Exception thrown : " + e);
        }
        catch (FileNotFoundException e) {

            System.out.println("Exception thrown : " + e);
        }
    }
}

Output:

Status : SHA-1 Message Digest from SUN, 

Reference: https://docs.oracle.com/javase/9/docs/api/java/security/DigestInputStream.html#getMessageDigest–