Java Data Types

Data types in Java are divided into two types

• Primitive Data Types – includes byte, short, int, float, double, boolean and char
• Non-primitive Data Types – such as string, Arrays and Classes
  
  

Primitive Data Types

A primitive data type specifies the size and type of variable values. There are eight primitive data types in Java:

Numbers

The primitive data types for numbers are divided into

• Integer types – Stores whole numbers which could be positive or negative, without decimals. Valid types are int, short, long and byte
• Floating types – Stores number with a fractional part, containing one or more decimals. Valid types are float and double.
  

Note: Though there are many numeric data types in Java, the most commonly used are int ( for whole numbers ) and double ( for floating numbers )

Primitive Data type  Examples

byte numByte = 100;
short numShort = 5000;
int numInt = 100000;
long numLong = 15000000000000L;
float numFloat = 6.85F;
double numDouble = 1.9999999999d;
boolean isTrue = true;
boolean isFalse = false;
char a = 65, b = 66; //ASCII values
String value = "SparkDatabox";
             
System.out.println("byte:" +numByte);
System.out.println("short:" +numShort);
System.out.println("int:" +numInt);
System.out.println("long:" +numLong);
System.out.println("float:" +numFloat);
System.out.println("double:" +numDouble);
System.out.println("boolean:" +isTrue);
System.out.println("boolean:" +isFalse);
System.out.println("ASCII value of'65':" +a);
System.out.println("ASCII value of'66':" +b);
System.out.println("String:" +value)

Output

byte:100
short:5000
int:100000
long:15000000000000
float:6.85
double:1.9999999999
boolean:true
boolean:false
ASCII value of'65':A
ASCII value of'66':B
String:SparkDatabox

Non-Primitive Data Types

These are called reference types because they refer to objects. The main difference between primitive and non-primitive data types are:

• Primitive types are pre-defined in Java, whereas the non-primitive types are created by the programmer and it is not defined by the Java.
• Non-primitive methods are used to call methods to perform certain operations, while primitive types cannot.
• A primitive data type should have a value always whereas a non-primitive type can be null.
• The primitive type should always starts with lower case and the non-primitive type should always starts with upper case.

Non-Primitive Data types examples – Strings, Arrays, Classes, Interfaces, etc.