KeyFactory getInstance() method in Java with Examples

Last Updated : 09 Jun, 2020

getInstance(String algorithm)

The getInstance() method of java.security.KeyFactory class returns a object of KeyFactory type that applys 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 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 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 applys 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 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 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-

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