KeyFactory getInstance() method in Java with Examples

getInstance(String algorithm)

The getInstance() method of java.security.KeyFactory class returns a object of KeyFactory type that applies the assigned KeyFactory algorithm. Syntax:

public static KeyFactory
  getInstance(String algorithm)
  throws NoSuchAlgorithmException

Parameters: This method seeks the standard Algorithm as a parameter whose instance is to be created to this KeyFactory instance. Return Value: This method returns a new key factory object. Exception: This method throws following exception:

• NoSuchAlgorithmException: if no provider is available to support an key factory spi application for the particular algorithm.
• NullPointerException: if algorithm is null.

Below are the examples to illustrate the getInstance() method: Example 1:

Java

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

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

public class GFG1 {
    public static void main(String[] argv)
    {

        try {

            // creating the object of KeyFactory
            // and getting instance
            // By using getInstance() method
            KeyFactory sr
                = KeyFactory.getInstance("DSA");

            // getting the algorithm of KeyFactory object
            String str = sr.getAlgorithm();

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

        catch (NoSuchAlgorithmException e) {

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

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

Output:

algorithm : DSA

Example 2: To show NoSuchAlgorithmException 

Java

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

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

public class GFG1 {
    public static void main(String[] argv)
    {

        try {

            // creating the object of KeyFactory
            // and getting instance
            // By using getInstance() method
            KeyFactory sr = KeyFactory.getInstance("GEEKS");

            // getting the algorithm of KeyFactory object
            String str = sr.getAlgorithm();

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

        catch (NoSuchAlgorithmException e) {

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

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

Output:

Exception thrown :
 java.security.NoSuchAlgorithmException:
 GEEKS KeyFactory not available

getInstance(String algorithm, String provider)

The getInstance() method of java.security.KeyFactory class returns a object of KeyFactory type that applies the assigned KeyFactory algorithm and assigned provider object. Syntax:

public static KeyFactory
  getInstance(String algorithm, String provider)
  throws NoSuchAlgorithmException

Parameters: This method seeks the following arguments as a parameters:

• algorithm: which is the name of the algorithm specified to get the instance.
• provider: which is the name of the provider to be specified

Return Value: This method returns an new key factory object. Exception: This method throws following exceptions:

• NoSuchAlgorithmException:– if no provider is available to support an key factory spi application for the particular algorithm.
• IllegalArgumentException:– if the provider is null.
• NullPointerException:– if algorithm is null

Below are the examples to illustrate the getInstance() method: Example 1:

Java

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

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

public class GFG1 {
    public static void main(String[] argv)
    {
        try {
            // creating the object of KeyFactory
            // and getting instance
            // By using getInstance() method
            KeyFactory sr
                = KeyFactory.getInstance(
                    "DSA", "SUN");

            // getting the algorithm of KeyFactory object
            String str = sr.getAlgorithm();

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

        catch (NoSuchAlgorithmException e) {

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

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

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

Output:

algorithm : DSA

Example 2: To show NoSuchAlgorithmException 

Java

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

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

public class GFG1 {
    public static void main(String[] argv)
    {
        try {
            // creating the object of KeyFactory
            // and getting instance
            // By using getInstance() method
            KeyFactory sr
                = KeyFactory.getInstance(
                    "RSA", "SUN");

            // getting the algorithm of KeyFactory object
            String str = sr.getAlgorithm();

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

        catch (NoSuchAlgorithmException e) {

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

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

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

Output:

Exception thrown :
 java.security.NoSuchAlgorithmException:
 no such algorithm: RSA for provider SUN

Reference: https://docs.oracle.com/javase/9/docs/api/java/security/KeyFactory.html#getInstance-java.lang.String-