There are eight primitive data types supported by Java programming language :
byte
The byte data type is an 8-bit signed two's complement integer. It ranges from -128 to127 (inclusive). This type of data type is useful to save memory in large arrays.. We can also use byte instead of int to increase the limit of the code. The syntax of declaring a byte type variable is shown as:
byte b = 5;
short
The short data type is a 16-bit signed two's complement integer. It ranges from -32,768 to 32,767.short is used to save memory in large arrays. The syntax of declaring a short type variable is shown as:
short s = 2;
int
The int data type is used to store the integer values not the fraction values. It is a 32-bit signed two's complement integer data type. It ranges from -2,147,483,648 to 2,147,483,647 that is more enough to store large number in your program. However for wider range of values use long. The syntax of declaring a int type variable is shown as:
int num = 50;
long
The long data type is a 64-bit signed two's complement integer. It ranges from -9,223,372,036,854,775,808 to 9,223,372,036,854,775,807. Use this data type with larger range of values. The syntax of declaring a long type variable is shown as:
long ln = 746;
float
The float data type is a single-precision 32-bit IEEE 754 floating point. It ranges from 1.40129846432481707e-45 to 3.40282346638528860e+38 (positive or negative). Use a float (instead of double) to save memory in large arrays. We do not use this data type for the exact values such as currency. For that we have to use java.math.BigDecimal class. The syntax of declaring a float type variable is:
float f = 105.65;float f = -5000.12;
double
This data type is a double-precision 64-bit IEEE 754 floating point. It ranges from 4.94065645841246544e-324d to 1.79769313486231570e+308d (positive or negative). This data type is generally the default choice for decimal values. The syntax of declaring a double type variable is shown as:
double d = 6677.60;
char
The char data type is a single 16-bit, unsigned Unicode character. It ranges from 0 to 65,535. They are not integral data type like int, short etc. i.e. the char data type can't hold the numeric values. The syntax of declaring a char type variable is shown as:
char caps = 'c';
boolean
The boolean data type represents only two values: true and false and occupy is 1-bit in the memory. These values are keywords in Java and represents the two boolean states: on or off, yes orno. We use boolean data type for specifying conditional statements as if, while, do, for. In Java, trueand false are not the same as True and False. They are defined constants of the language. The syntax of declaring a boolean type variable is shown as:
boolean result = true;
The ranges of these data types can be described with default values using the following table:
Data Type Default Value (for fields) Size (in bits) Minimum Range Maximum Range byte 0 Occupy 8 bits in memory -128 +127 short 0 Occupy 16 bits in memory -32768 +32767 int 0 Occupy 32 bits in memory -2147483648 +2147483647 long 0L Occupy 64 bits in memory -9223372036854775808 +9223372036854775807 float 0.0f Occupy 32-bit IEEE 754 floating point 1.40129846432481707e-45 3.40282346638528860e+38 double 0.0d Occupy 64-bit IEEE 754 floating point 4.94065645841246544e-324d 1.79769313486231570e+308d char '\u0000' Occupy 16-bit, unsigned Unicode character 0 to 65,535 boolean false Occupy 1- bit in memory NA NA
Integer numbers
An integer data type can hold a whole number, but no fraction. Integers may be either signed (allowing negative values) or unsigned (nonnegative values only). Typical sizes of integers are:
| Size | Names | Signed Range | Unsigned Range |
|---|---|---|---|
8 bits
|
Byte
|
−128 to +127
|
0 to 255
|
16 bits
|
Word, short int
|
−32,768 to +32,767
|
0 to 65,535
|
32 bits
|
Double Word, long int (win32, win64, 32-bit Linux[1])
|
−2,147,483,648 to +2,147,483,647
|
0 to 4,294,967,295
|
64 bits
|
long int (C in 64-bit linux[1]), long long (C), long (Java, the signed integer variant only[2]))
|
−9,223,372,036,854,775,808 to +9,223,372,036,854,775,807
|
0 to 18,446,744,073,709,551,615
|
unlimited
|
Bignum
|