Java Data types

1. JavaThe basic data type is only8Species arebyte， Short，int，Long，float，Double，Char，BooleanNoteStringNoJavaThe basic data type)

Data type	Size/bit	can represent a range of data
Byte (bytes)	8	-128~127
Short (shorter integer type)	16	-32768~32767
int (integral type)	32	-More than 2.1 billion ~ 2.1 billion
Long (integer)	64	-2^63~ (2^63)-1
Float (single precision)	32	-3.4e38~3.4e38
Double (dual precision)	64	-1.7e308~1.7e308
char (character)	16	0~65535
Boolean (Boolean)	-	True or False

(Attached: long and double are all 64 bits.) Why is a double representing so much scope? ）

1.1. Data type Conversion

　　1.1.1, automatic type conversion: Small type to large type

1.1.2, coercion type conversions: large types to small types

Strong turns are likely to overflow or loss of precision

1.1.3, data types from small to large in the order of: Byte + short (char) = int = Long = = Float = Double

1.2. Assignment and operation

1.2.1, integer direct value can be directly assigned to Byte,short,char, but not out of range

char c =; // Char type is a character, essentially a code int, which holds an integral type.  // based on Unicode character set encoding, each character has a corresponding code

1.2.2 and Byte,short,char data participate in the operation, the first is converted to int re-operation

 Short B1 = 5;  Short b2 = 6;  Short B3 = (short) (b1+B2); // the B1 and B2 operations here are automatically converted to int, so you must be strong to short to assign a value to B3

　　

1.2.3, assign Value

The direct volume range is a compile error and the overrun is overflow when the operation is over

long a = 1000000000*2*10l//20 billion Llong b = 1000000000*3*10l/ / overflow long c = 1000000000l*3*10//30 billion L//  When using a long type for large numeric operations, it is best to write the L// after the first number to indicate that the number is long, avoiding the default integer operation
Note: The direct amount of the long integer, the number must be added L or l

1.2.4, common data unit conversions

1g=1024m ( MB )

1m=1024kb ( kbytes )

1kb=1024b ( bytes )

1b=8bit ( bit )

1.2.5, the base type "=" is the variable assignment, and the reference type "=" is the reference variable that points to an address value

Java Data types