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1. Constants
Constants in Java are fixed values that do not change during program execution. They are declared using the final keyword. Once a value is assigned to a final variable, it cannot be reassigned.
2. Variables
Variables are named memory locations used to store data that can change during the execution of a program. They must be declared with a specific data type before use.
3. Data Types
Data types classify the type of data a variable can hold, determining the range of values and the operations that can be performed on it. Java has two main categories of data types:
Primitive Data Types: These are fundamental data types that store simple values. Examples include byte, short, int, long, float, double, boolean, and char.
Non-Primitive (Reference) Data Types: These are more complex data types that refer to objects. Examples include String, Arrays, and custom classes.
4. Java Type Casting
Type casting is the process of converting a value from one data type to another. This is necessary when performing operations involving different data types or when assigning values between incompatible types. There are two types of casting: