java built-in data types

Constant is a quantity that will not be modified while the program is running.

　Using the final keyword in Java to modify constant declarations is similar to variables

　finaldouble PI =3.1415927;

　Although constant names can also be in lowercase, capital letters are usually used to represent constants for ease of identification.

　Literals can be assigned to variables of any built-in type. For example

　byte a =68; char a ='A'

　Byte, int, long, and short can all be represented in decimal, hexadecimal and octal.

When using constants, the prefix 0 represents octal and the prefix 0x represents hexadecimal. For example

　intdecimal=100; int octal =0144; int hexa =0x64;

　Like other languages, Java's string constants are also character sequences contained between two quotation marks. The following is an example of a string literal

　　"Hello World" "twonlines" ""This is in quotes""

　 Both string constants and character constants can contain any Unicode characters. For example

　char a ='u0001'; String a ="u0001";

　Java language supports some special escape character sequences.