Free Online 5 Minute Java Test

Question: A user thread of a GUI application needs to perform certain security sensitve operations upon receiving system events. For this purpose, a call back handler has been registered with the system by the user thread based upon inputs from the GUI. The operations should be executed only if the user has appropriate permissions as per the security policy.

The following code shows the call back handler:

public class ProtectedCallbackHandler implements Runnable{

    final String action;

    public ProtectedCallbackHandler(String action){

        this.action = action;

    }

    public void run(){

    AccessController.doPrivileged(

        new PrivilegedAction() {

            public Void run() {

                //Do sensitive operations based upon action value

                return null;

            }

        });           

    }

}

Identify correct statements.

Select 1 option(s)

Question: You have been given an array of objects and you need to process this array as follows -

1. Call a method on each object from first to last one by one.
2. Call a method on each object from last to first one by one.
3. Call a method on only those objects at even index (0, 2, 4, 6, etc.)

Which of the following are correct?

Select 1 option(s)

Question: Given:

class Person{

  private String name;

  private java.util.Date dob;

  public Person(String name, java.util.Date dob){

     this.name = name;

     this.dob = (java.util.Date) dob.clone();

     if(!validateDob(this.dob))

                 throw new IllegalArgumentException("dob cannot be in future");

  }

  protected boolean validateDob(java.util.Date dob){

      return !dob.after(new java.util.Date());

  }

  //getter methods for fields not shown

}

What changes should be made to make this class immutable?

Select 2 option(s)

Question: Checked exceptions are meant for...

Select 1 option(s)

Question: Identify correct statements about the following code-

interface Drink{

  default double getAlcoholPercent(){

     return 0.0;

  }

  static double computeAlcoholPercent(){

      return 0.0;

  }

}

interface ColdDrink extends Drink{

  String getName();

}

class CrazyDrink implements ColdDrink{

   // INSERT CODE HERE

}

Select 1 option(s)

Question: Given the following code:

Locale.setDefault(Locale.ITALY);

Locale loc = new Locale.Builder().setLanguage("en").build();

ResourceBundle rb = ResourceBundle.getBundle("mymsgs", loc);

System.out.println(rb.getString("helloMsg"));

and the following properties files:

mymsgs.properties

mymsgs_en_IT.properties

mymsgs_en.properties

mymsgs_IT.properties

Which of the following statements are correct?

Select 2 option(s)