AlgorithmParameters getInstance() method in Java with Examples

getInstance(String algorithm)

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

public static AlgorithmParameters
  getInstance(String algorithm)
  throws NoSuchAlgorithmException

Parameters: This method seeks the standard Algorithm as a parameter.
Return Value: This method provides a new algorithm parameters object.
Exception: This method throws following exception: 

• NoSuchAlgorithmException:– if no provider is available to support an algorithm parameter spi application for the particular algorithm.
• 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 {
            // creating the object of AlgorithmParameters
            // and getting instance
            // By using getInstance() method
            AlgorithmParameters sr
                = AlgorithmParameters
                      .getInstance("DES");

            // getting the status
            // of AlgorithmParameters 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 : null

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 AlgorithmParameters
            // and getting instance
            // By using getInstance() method
            AlgorithmParameters sr
                = AlgorithmParameters.getInstance("GFG");

            // getting the status
            // of AlgorithmParameters 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 AlgorithmParameters not available

getInstance(String algorithm, Provider provider)

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

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

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

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

Return Value: This method provides a new algorithm parameters object.
Exception: This method throws following exceptions: 

• NoSuchAlgorithmException: if no provider is available to support an algorithm parameter spi application for the particular algorithm.
• 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 {
            // creating AlgorithmParameterGenerator object
            // and getting instance
            // By using getInstance() method
            AlgorithmParameterGenerator sr
                = AlgorithmParameterGenerator
                      .getInstance("DiffieHellman");

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

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

            // creating AlgorithmParameterGenerator object
            // and getting instance
            // 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@63947c6b

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 AlgorithmParameterGenerator object
            // and getting instance
            // 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();

            // creating AlgorithmParameterGenerator object
            // and getting instance
            // By using getInstance() method
            AlgorithmParameterGenerator sr1
                = AlgorithmParameterGenerator
                      .getInstance("GFG", 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:
 no such algorithm: GFG for provider SUN

Reference: https://docs.oracle.com/javase/9/docs/api/java/security/AlgorithmParameters.html