Variables and Primitive Data types

Lecture 3:- Variables and Primitive Data types

Variables and primitive data types are fundamental concepts in programming languages, including Java. They are used to store and manipulate data in a program. Let's delve into each of them:

1. Variables: A variable is a named memory location that holds a value. It allows you to store and retrieve data during program execution. In Java, you need to declare a variable before using it. The declaration includes the variable's data type and name.

Syntax for variable declaration:

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data_type variableName;

Example:

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int age; double salary; String name;

1. Primitive Data Types: Java has several primitive data types, which are the most basic data types built into the language. They are not objects and don't have methods. There are eight primitive data types in Java:

• Numeric Types:
  • byte: 8-bit signed integer. Range: -128 to 127.
  • short: 16-bit signed integer. Range: -32,768 to 32,767.
  • int: 32-bit signed integer. Range: -2^31 to 2^31 - 1.
  • long: 64-bit signed integer. Range: -2^63 to 2^63 - 1.
  • float: 32-bit floating-point. Can store fractional numbers.
  • double: 64-bit floating-point. Can store fractional numbers with higher precision.
• Other Primitive Types:
  • char: 16-bit Unicode character. Represents a single character, like 'A' or '5'.
  • boolean: Represents true or false values.

Example of using primitive data types with variables:

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int age = 25; double salary = 50000.50; char grade = 'A'; boolean isEmployed = true;

It's important to choose the appropriate data type for your variables based on the data you want to store to optimize memory usage and ensure the correct behavior of your program.

Java also has non-primitive data types, known as reference types, which include objects, arrays, and interfaces. Unlike primitive types, these are more complex and store references to the actual data, which reside in the heap memory.

Keep in mind that Java is a statically-typed language, meaning you need to declare the data type of a variable explicitly. Other languages, like Python, are dynamically-typed, where the data type is inferred at runtime.