Storing and Manipulating Data

Computers need to store information and perform calculations. In Java, we use variables to store data, data types to define the kind of data, and operators to manipulate it.

Common Data Types

• int: Whole numbers (e.g., 10, -3)
• double: Decimal numbers (e.g., 3.14, -0.001)
• boolean: True or false
• char: Single characters, like 'A' or 'z'
• String: Text, like "Hello!"

Operators

• Arithmetic: +, -, *, /, %
• Assignment: =, +=, -=
• Comparison: ==, !=, <, >, <=, >=
• Logical: &&, ||, !

Example Code

int age = 16;
double price = 4.99;
boolean isStudent = true;
String name = "Taylor";

if (isStudent && age < 18) {
  System.out.println(name + " gets a discount!");
}

Real-World Applications

Variables and operators are everywhere: from banking systems tracking balances to video games calculating health points.

Tips

• Choose meaningful variable names.
• Match the data type to the information you want to store.