Class And Object In Java Quiz

1. Which of the following is true about private constructor?

Private constructor makes sure only one instance of a class exists at any time

Private constructor makes sure multiple instances of a class exist at any time

Private constructor ensures the instantiation of a class with ease

Private constructor facilitates creation of objects in other classes

2. What will be the behavior of Java script if this() and super() used in the same method?

Runtime error

Throws exception

Runs successfully

3. In Java, which of these operators is used to place memory to array variable?

Malloc

Alloc

New

New malloc

4. What is true about protected constructor?

It can be called directly

It can only be called using super()

It can be used outside package

It can be instantiated even if the child is in a completely different package

5. Abstract class cannot have a constructor.

True

False

6. If the constructor has a return type, what will be its behavior?

Compilation error

Runtime error

Compilation and runs successfully

Only String return type is allowed

7. Which one of the following is not a correct array declaration?

Int [] arr = new int[5]

Int arr[] = new int[5]

Int arr[] = int [5] new

8. Which of these class can be used to make an object whose character sequence is mutable?

String()

String() & StringBuffer()

StringBuffer()

None of the mentioned

9. If one has to extract a single character from a String object, which of these method of class String can be used?

CHARAT()

Chatat()

CharAt()

ChatAt()

Option 5

10. Which of these is an incorrect statement?

String objects are immutable, they can never be changed

String object usually point to another reference of a string variable

StringBuffer class can be used to store string in a buffer to be used later

None of the mentioned