Java supports several built-in data types that are used to store and manipulate data in a program. Here are the common data types in Java:
Primitive Data Types:
byte: 8-bit integer value (-128 to 127)
short: 16-bit integer value (-32,768 to 32,767)
int: 32-bit integer value (-2^31 to 2^31-1)
long: 64-bit integer value (-2^63 to 2^63-1)
float: 32-bit floating point value
double: 64-bit floating point value
boolean: true/false value
char: single 16-bit Unicode character
Reference Data Types:
String: a sequence of characters
Arrays: a number of elements of the same type
Classes: a user-defined data type
Primitive data types are simple data types that are used to represent basic values, while reference data types are more complex data types that are used to represent objects and collections.
In Java, variables with datatype must be declared before the use. For example, to declare a variable of type int named "myNumber", you would use the following syntax:
int myNumber;
You can also initialize the variable at the same time as you declare it, like this:
int myNumber = 10;
Java also provides wrapper classes for the primitive data types, such as Integer, Double, and Boolean, which allow them to be used as objects.