Test Preparation on JAVA- Test Prep.- Classes and Methods-1

1.

What is the stored in the object obj in following lines of Java code?

   box obj;

1Memory address of allocated memory of object
2NULL
3Any arbitrary pointer
4Garbage

Explanation: Memory is allocated to an object using new operator. box obj; just declares a reference to object, no memory is allocated to it hence it points to NULL.

2.

Which of these keywords is used to make a class?

1class
2struct
3int
4none of the mentioned

3.

Which of the following is a valid declaration of an object of class Box?

1Box obj = new Box();
2Box obj = new Box;
3obj = new Box();
4new Box obj;

4.

Which of these operators is used to allocate memory for an object?

1malloc
2alloc
3new
4give

Explanation: Operator new dynamically allocates memory for an object and returns a reference to it. This reference is address in memory of the object allocated by new.

5.

Which of these statement is incorrect?

1very class must contain a main() method
2Applets do not require a main() method at all
3There can be only one main() method in a program
4main() method must be made public

Explanation: Every class does not need to have a main() method, there can be only one main() method which is made public.

Test Preparation on JAVA- Test Prep.- Classes and Methods-1

What is the stored in the object obj in following lines of Java code?

box obj;

Which of these keywords is used to make a class?

Which of the following is a valid declaration of an object of class Box?

Which of these operators is used to allocate memory for an object?

Which of these statement is incorrect?

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