Core Java - [Constants/DataTypes]

♠ Posted by Unknown in Core Java at 23:11

Java Constants and Datatypes

JAVA (CONSTANTS) :-

1.         Numeric Constants

a.         Integer Constants :- 123, -321, 0, 654321,  Octal, Hexadecimal

b.         Real Constants :- 0.0083, -0.75, 435.36, 0.65e4, 12e-2, 1.5e+5

2.         Character Constants

a.         Single Character Constants :- ‘5’, ‘X’, ‘;’, ‘ ‘

b.         String Constants :- “Hello Java”, “1997”, “?....!”, “5+3”, “X”

JAVA (DATATYPES) :-

1.         primitive (Intrinsic) :

a.         Numeric :

i.          Integer

1.         Byte (1 byte)  -128 to +127

2.         Short (2 bytes)  -32,768 to +32,767

3.         int (4 bytes) -2,147,483,648 to +2,147,483,647

4.         long (8 bytes) -9,223,372,036,854,775,808 to +9,223,372,036,854,775,807

ii.         Floating Point

1.         float (4 bytes) 3.4e-038 to 3.4e+038

2.         double (8 bytes) 1.7e-308 to 1.7e+308

b.         Non-Numeric :

i.          Character (2 bytes) Holds singles character only

ii.         Boolean (1 bit) Holds Only true or false

2.         Non-primitive :

a.         Classes

b.         Interface

c.         Arrays

Characters :-

In Java, the data type used to sore characters is char. However C/C++ programmers beware: char in Java is not the same as char in C/C++. In C/C++, char is an integer type that is 8 bits wide. This is not the case in Java. Instead, Java uses Unicode to represent characters. Unicode defines a fully international character set that can represent all of the characters found in all human languages. It is a unification of dozens of character set, such as Latin, Greek, Arabic, Cyrillic, Hebrew, Katakana, Hangul, and many more. For this purpose, it requires 16 bits. Thus, in Java char is a 16-bit type (2 bytes). The range of a char is 0 to 65,536. There are no negative chars. The standard set of characters known as ASCII still ranges from 0 to 127 as always, and the extended 8-bit character set, ISO-Latin-1, ranges from 0 to 255. Since Java is designed to allow applets to be written for worldwide use, it makes sense that it would use Unicode to represent characters. Of course, the use of Unicode is somewhat inefficient for languages such as English, German, Spanish, or French whose characters can easily be contained within 8 bits. But such is the price that must be pain for global portability.