KeyStore containsAlias() method in Java with Examples

The containsAlias() method of java.security.KeyStore class is used to check the presence of the requested alies.

Syntax:

public final boolean containsAlias(String alias)
  throws KeyStoreException

Parameter: This method seeks the name of the alias as a parameter of String type of which the entry is to be checked.



Return Value: This method returns a Boolean value stating the result.

Exception: This method throws KeyStoreException if you don’t initialize this keystore.

Note: All the programs in this article won’t run on online IDE as no ‘privatekey’ Keystore exists. You can check this code on Java compiler on your system. To check this code, create a Keystore ‘privatekey’ on your system and set your own keystore password to access that keystore.

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

Example 1:

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// Java program to demonstrate
// getInstance() method
  
import java.security.*;
import java.security.cert.*;
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 usng getInstance() method
            KeyStore sr = KeyStore.getInstance("JKS");
  
            // Keystore password is require
            // to access Keystore
            char[] pass = ("123456").toCharArray();
  
            // creating and intializing
            // object of InputStream
            InputStream is
                = new FileInputStream(
                    "f:/java/private key.store");
  
            // intializing keystore object
            sr.load(is, pass);
  
            // checking the presence of the aliases
            // using containsAlias() method
            boolean status
                = sr.containsAlias("ftpkey");
  
            // display the result
            if (status)
                System.out.println("This aliases is present");
            else
                System.out.println("This aliases is absent");
        }
  
        catch (NoSuchAlgorithmException e) {
  
            System.out.println("Exception thrown : " + e);
        }
        catch (NullPointerException e) {
  
            System.out.println("Exception thrown : " + e);
        }
        catch (KeyStoreException e) {
  
            System.out.println("Exception thrown : " + e);
        }
        catch (FileNotFoundException e) {
  
            System.out.println("Exception thrown : " + e);
        }
        catch (IOException e) {
  
            System.out.println("Exception thrown : " + e);
        }
        catch (CertificateException e) {
  
            System.out.println("Exception thrown : " + e);
        }
    }
}

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Output:

This aliases is present

Example 2: For KeyStoreException

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// Java program to demonstrate
// getInstance() method
  
import java.security.*;
import java.security.cert.*;
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 usng getInstance() method
            KeyStore sr = KeyStore.getInstance("JKS");
  
            // intializing keystore object
            // sr.load(is, pass);
  
            // checking the presence of the aliases
            // using containsAlias() method
            boolean status = sr.containsAlias("gfg");
  
            // display the result
            if (status)
                System.out.println("This aliases is present");
            else
                System.out.println("This aliases is absent");
        }
        catch (NullPointerException e) {
  
            System.out.println("Exception thrown : " + e);
        }
        catch (KeyStoreException e) {
  
            System.out.println("Exception thrown : " + e);
        }
    }
}

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Output:

Exception thrown :
 java.security.KeyStoreException:
 Uninitialized keystore

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

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