AlgorithmParameterGenerator getInstance() method in Java with Examples

getInstance(String algorithm)

The getInstance() method of java.security.AlgorithmParameterGenerator class is used to return an object of AlgorithmParameterGenerator type that implements the specified algorithm.
Syntax:

public static AlgorithmParameterGenerator 
  getInstance(String algorithm)
    throws NoSuchAlgorithmException

Parameters: This method takes the standard name of Algorithm as a parameter.
Return Value: This method returns the new AlgorithmParameterGenerator object.
Exception: This method throws following exception: 

• NoSuchAlgorithmException: if no Provider supports an AlgorithmParameterGeneratorSpi implementation for the specified algorithm.
• NullPointerException: if the specified 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 {
            // Getting instance of
            // AlgorithmParameterGenerator
            // By using getInstance() method
            AlgorithmParameterGenerator sr
                = AlgorithmParameterGenerator
                      .getInstance("DSA");

            // getting the status of
            // AlgorithmParameterGenerator object
            String str = sr.toString();

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

        catch (NoSuchAlgorithmException e) {

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

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

Output:

Status: java.security.AlgorithmParameterGenerator@232204a1

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 {
            // Getting instance of
            // AlgorithmParameterGenerator
            // By using getInstance() method
            AlgorithmParameterGenerator sr
                = AlgorithmParameterGenerator
                      .getInstance("GFG");

            // getting the status of
            // AlgorithmParameterGenerator object
            String str = sr.toString();

            // printing the status
            System.out.println("Status: " + 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:
 GFG AlgorithmParameterGenerator not available

Signature getInstance(String algorithm, Provider provider)

The getInstance() method of java.security.AlgorithmParameterGenerator class is used to return a AlgorithmParameterGenerator object that implements the specified signature algorithm and specified provider object.
Syntax:

public static AlgorithmParameterGenerator
  getInstance(String algorithm, Provider provider)
    throws NoSuchAlgorithmException

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

• algorithm: which is the name of the algorithm requested.
• provider: which is the provider specified

Return Value: This method returns the new AlgorithmParameterGenerator object.
Exception: This method throws following exceptions: 

• NoSuchAlgorithmException: if a AlgorithmParameterGeneratorSpi implementation for the specified algorithm is not available from the specified Provider object.
• IllegalArgumentException: if the provider is null.
• NullPointerException: if the 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 {
            // Getting instance of
            // AlgorithmParameterGenerator
            // By using getInstance() method
            AlgorithmParameterGenerator sr
                = AlgorithmParameterGenerator
                      .getInstance("DSA");

            // creating Provider object
            Provider pd = sr.getProvider();

            // getting algorithm name
            // by using getAlgorithm() method
            String algo = sr.getAlgorithm();

            // Getting instance of
            // AlgorithmParameterGenerator
            // By using getInstance() method
            AlgorithmParameterGenerator sr1
                = AlgorithmParameterGenerator
                      .getInstance(algo, pd);

            // getting the status of
            // AlgorithmParameterGenerator object
            String str = sr1.toString();

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

        catch (NoSuchAlgorithmException e) {

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

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

Output:

Status: java.security.AlgorithmParameterGenerator@232204a1

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 {
            // Getting instance of
            // AlgorithmParameterGenerator
            // By using getInstance() method
            AlgorithmParameterGenerator sr
                = AlgorithmParameterGenerator
                      .getInstance("GFG");

            // creating Provider object
            Provider pd = sr.getProvider();

            // getting algorithm name
            // by using getAlgorithm() method
            String algo = sr.getAlgorithm();

            // Getting instance of
            // AlgorithmParameterGenerator
            // By using getInstance() method
            AlgorithmParameterGenerator sr1
                = AlgorithmParameterGenerator
                      .getInstance(algo, pd);

            // getting the status of
            // AlgorithmParameterGenerator object
            String str = sr1.toString();

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

        catch (NoSuchAlgorithmException e) {

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

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

Output:

Exception thrown:
 java.security.NoSuchAlgorithmException:
 GFG AlgorithmParameterGenerator not available

Reference:

• https://docs.oracle.com/javase/9/docs/api/java/security/AlgorithmParameterGenerator.html#getInstance-java.lang.String-
• https://docs.oracle.com/javase/9/docs/api/java/security/AlgorithmParameterGenerator.html#getInstance-java.lang.String-java.security.Provider-