Java Datatypes — some Quality stuff

Broadly divided as primitive and non primitive data types

Primitive types

These datatypes come out of the box in Java

(datatype-default-memory/size)

boolean— false — 1bit
int — 0–-4 bytes range 2-³¹ to 2³¹-1
byte — 0–-1 byte
short — 0–-2 bytes
long — 0L — 8 bytes
float — 0.0f — single precision- 4bytes
double — 0.0d-double precision — 8 bytes
char — ‘\u0000’ — Unicode character defaults to NUL or value of 0

Points to be noted:

please refer Unicode system- why preferred for Java.
We cannot assign null values to a primitive datatype

when we try to assign byte p = 130, which is greater than its range it will throw

Type mismatch: cannot convert from int to byte

We can use hexadecimal, Octal, decimal declarations for int datatype

int i =0X65 returns 101
based on 5*16⁰+6*16¹

Wrapper Class

Wrapper classes are used to map the primitive types in an object format.,As we all know that Collections don’t accept the primitives. Wrapper will be useful in that case

Example for a wrapper class

Integer i = new Integer(1);
or Integer i=1;

In our latest version of Java we don’t need to manually convert a primitive to Wrapper and vice-versa.

The concept of Autoboxing and Unboxing does it for us

int i=0;
Integer x= i;
will work for sure in Java 8 since Autoboxing is there

Unboxing works in the reverse

We can also convert from one datatype to another in a wrapper class using the parse functions

String x =”100";
Integer i = Integer.parseInt(x);
will convert it to Integer datatype

The wrapper classes are available for all the primitives..,

So that’s a quick refresh on the datatypes in Java.,

Have fun and Happy coding!!!!!