Java Data Types
Understanding different types of data in Java programming
📊 What are Java Data Types?
Java data types specify the different sizes and values that can be stored in variables. They define what kind of data a variable can hold, like numbers, characters, or true/false values.
// Different data types in Java
int age = 25; // Integer number
double price = 19.99; // Decimal number
char grade = 'A'; // Single character
boolean isActive = true; // True or false
Output:
age: 25
price: 19.99
grade: A
isActive: true
Types of Java Data Types
Integer Types
Store whole numbers
int count = 100;
long population = 7800000000L;Decimal Types
Store numbers with decimal points
float temperature = 36.5f;
double distance = 384400.0;Character Type
Store single characters
char letter = 'J';
char symbol = '@';Boolean Type
Store true or false values
boolean isReady = true;
boolean isComplete = false;🔹 Primitive Data Types
Java has 8 primitive data types with specific sizes and ranges:
// Integer types
byte smallNumber = 127; // -128 to 127
short mediumNumber = 32000; // -32,768 to 32,767
int regularNumber = 2000000; // -2 billion to 2 billion
long bigNumber = 9000000000L; // Very large numbers
// Decimal types
float decimal1 = 3.14f; // 7 decimal digits
double decimal2 = 3.14159265; // 15 decimal digits
// Other types
char character = 'A'; // Single character
boolean flag = true; // true or falseOutput:
smallNumber: 127
mediumNumber: 32000
regularNumber: 2000000
bigNumber: 9000000000
decimal1: 3.14
decimal2: 3.14159265
character: A
flag: true
🔹 String Data Type
String is a reference type that stores text:
// String examples
String name = "John Doe";
String message = "Welcome to Java!";
String empty = "";
// String methods
System.out.println(name.length()); // Get length
System.out.println(name.toUpperCase()); // Convert to uppercase
System.out.println(message.contains("Java")); // Check if contains textOutput:
8
JOHN DOE
true
🔹 Choosing the Right Data Type
Select data types based on your needs:
// Age of a person (0-150)
byte age = 25;
// Price of a product
double price = 29.99;
// Student grade
char grade = 'A';
// Is user logged in?
boolean isLoggedIn = true;
// Person's full name
String fullName = "Alice Johnson";Tips for choosing data types:
- int - Most common for whole numbers
- double - Best for decimal numbers
- String - For any text data
- boolean - For yes/no, true/false values