Chapter 3

Question 1

Does name of file must match name of class

Answer 1

Yes

Question 2

Is java case sensitive

Answer 2

Yes

Question 3

What is the purpose of static

Answer 3

So we can call a method without creating an object

Question 4

What is concatenate operator in java

Answer 4

+

Question 5

How we compare strings in java

Answer 5

string1.equals(string2)

Question 6

Is array a class in java

Answer 6

Yes

Question 7

What happens if we give value more than array size

Answer 7

Java sends exception

Question 8

What are primitives

Answer 8

The data types in java which are not objects. They are always in lower case.

Question 9

How much primitive data types in java

Answer 9

8

Question 10

What is stored at stack

Answer 10

Local variables, primitive data types

Question 11

What is stored at heap

Answer 11

Objects

Question 12

How primitive data types passes

Answer 12

By value

Question 13

How object passes

Answer 13

By reference

Question 14

What are wrapper classes

Answer 14

Through wrapper classes, we pass data types as reference (just like objects)

Question 15

What parseXxx do

Answer 15

It changes the datatype. e.g.
String value = “532”;
int d = Integer.parseInt(value);

Question 16

What is boxing/unboxing

Answer 16

In jdk 5.0 or above there is new feature called boxing/unboxing. It changes the primitive data type to object and vice verse with the help of iWrapper. e.g.
Integer iWrapper = 10;