Topic 2: Variables, Data Types and Operators

Q: What is a variable in Java?

A variable is a container that holds data that can be changed during program execution.

Q: What are the types of variables in Java?

Local variables, instance variables (non-static fields), and class variables (static fields).

Q: What is a data type?

A data type defines the kind of value a variable can hold, such as int, double, char, or boolean.

Q: What are the 8 primitive data types in Java?

byte, short, int, long, float, double, char, boolean

Q: What is the default value of an int, boolean, and reference type in Java?

int: 0, boolean: false, reference type: null

Q: What is the difference between primitive and reference data types?

Primitive types store actual values; reference types store memory addresses of objects.

Q: What is a literal in Java?

A literal is a fixed value assigned to a variable, like 5, 'A', or "Hello".

Q: What are arithmetic operators in Java?

+, -, *, /, %

Q: What are relational (comparison) operators in Java?

==, !=, >,

Q: What are logical operators in Java?

&& (AND), || (OR), ! (NOT)

Q: What is the difference between = and == in Java?

= is the assignment operator, == compares values (or references for objects).

Q: What is type casting in Java?

Converting one data type into another. Example: (int) 5.5 gives 5.

Q: What is the difference between implicit and explicit casting?

Implicit casting is automatic (e.g., int to double), explicit casting is manual using (type) syntax (e.g., double to int).