Day-13: Data Types in Java - Class-Specific and Object-Specific Data Types

1). Primitive Data Types:
The Java programming language is statically-typed, which means that all variables must first be declared before they can be used.

example: int grear = 1;

A primitive type is predefined by the language and is named by a reserved keyword.
Like int, byte, char,...

Primitive values do not share state with other primitive values.
Example: int grear = 1;
boolean grear_bike = true;
int total_output = grear + grear_bike
This is not possible.

byte: The byte data type is an 8-bit signed two's complement integer.

• 128 to 127. The byte data type can be useful for saving memory in large arrays.

short: The short data type is a 16-bit signed two's complement integer. It has a minimum value of -32,768 and a maximum value of 32,767 (inclusive). As with byte, the same guidelines apply .

int: By default, the int data type is a 32-bit signed two's complement integer, which has a minimum value of -231 and a maximum value of 231-1. In Java SE 8 and later, you can use the int data type to represent an unsigned 32-bit integer.

long: The long data type is a 64-bit two's complement integer. The signed long has a minimum value of -263 and a maximum value of 263-1. In Java SE 8 and later, you can use the long data type to represent an unsigned 64-bit long, which has a minimum value of 0 and a maximum value of 264-1.

float: The float data type is a single-precision 32-bit IEEE 754 floating point. Its range of values is beyond the scope of this discussion, but is specified in the Floating-Point Types, Formats, and Values section of the Java Language Specification.

double: The double data type is a double-precision 64-bit IEEE 754 floating point.

boolean: The boolean data type has only two possible values: true and false. Use this data type for simple flags that track true/false conditions. This data type represents one bit of information, but its "size" isn't something that's precisely defined.

char: The char data type is a single 16-bit Unicode character. It has a minimum value of '\u0000' (or 0) and a maximum value of '\uffff' (or 65,535 inclusive).

2). Non-Primitive Data Types:
the Java programming language also provides special support for character strings via the java.lang.String class. Enclosing your character string within double quotes will automatically create a new String object; for example, String s = "this is a string";. String objects are immutable, which means that once created, their values cannot be changed. The String class is not technically a primitive data type, but considering the special support given to it by the language, you'll probably tend to think of it as such.

Default Values:
The following chart summarizes the default values for the above data types.
Data Type Default Value (for fields)
byte 0
short 0
int 0
long 0L
float 0.0f
double 0.0d
char '\u0000'
String (or any object) null
boolean false

Datatypes also classified Class and Object Specific:

static String headquarters; - class specific
String bike_colour; - Object specific

public class Honda {

    static String headquarters;  // static variable shared by all instances / class level
    String bike_colour;         // object-specific variable / object level 

    public static void main(String[] args){
        Honda activa = new Honda(); 

        Honda.headquarters = "Japan";  // setting the static variable 
        activa.bike_colour = "Blue";   // setting the instance variable 

        System.out.println("Honda headquarters located at: " + Honda.headquarters);
        System.out.println("Honda bike colour is: " + activa.bike_colour);
    }
}

Output Like this.

Ref Doc : https://docs.oracle.com/javase/tutorial/java/nutsandbolts/datatypes.html

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