Java

Question 1

what is Encapsulation? How to define a well-encapsulated class?

Answer 1

• private variables

- access to these variables using public method

Question 2

what is overloaded method?

Answer 2

same class - same name - different parameter list

Question 3

• what is polymorphic / overridden method?

- relationship among access modifiers of overriding method & overridden method

Answer 3

• classes, that share inheritance

- same name - same number of method arguments - same return type

Question 4

what is checked exception?

Answer 4

java.lang.Exception

Question 5

• what is unchecked exception?

- type of unchecked exception? (7)

Answer 5

java.lang.Exception & java.lang.RuntimeException

Question 6

• what are error?

- type of error? (4)

Answer 6

-

Question 7

String is immutable –> what does this mean?

Answer 7

• once created, content not modified
• Methods that return a modified String value –> return a new String object
• original String value remains the same

Question 8

difference method - constructor

Answer 8

-

Question 9

what happens when a class implements an interface?

Answer 9

-

Question 10

derived class constructor - base class constructor

Answer 10

a derived class constructor must always call a base class constructor

Question 11

what values can be passed to case statement in switch?

Answer 11

• compile-time
• null is not accepted
• duplicate values are not accepted

Question 12

can switch work with Array? What can it work with?

Answer 12

• no
• byte, short, char, and int
• enumerated types
• String
• WrapUp