SCJP Sun Certified Java Programmer MCQ 4

Question 1

What is the output of the following code?
String s1 = "Java";
String s2 = "Java";
System.out.println(s1 == s2);

Accepted Answer

true

Answer

String literals are stored in the string pool, so s1 and s2 reference the same object, making == return true.

Question 2

Which collection class allows duplicate elements and maintains insertion order?

Accepted Answer

ArrayList

Answer

ArrayList allows duplicate elements and preserves the order in which elements were inserted.

Question 3

What does the 'super' keyword refer to when used inside a constructor?

Accepted Answer

The parent class constructor

Answer

super() in a constructor explicitly calls the parent class's constructor.

Question 4

Which of the following correctly describes method overloading in Java?

Accepted Answer

Same method name, different parameter list, in the same class

Answer

Overloading occurs when methods share the same name but differ in number or type of parameters within the same class.

Question 5

Which statement about abstract classes in Java is TRUE?

Accepted Answer

A class with at least one abstract method must be declared abstract

Answer

If a class contains any abstract method, the class itself must also be declared abstract.

SCJP - Sun Certified Java Programmer Practice Test