Java basic type and wrapper class detailed parsing _mssql2008

The Java language provides eight basic types. Six numeric types (four integers, two floating-point types), one character type, and one Boolean type.

1, Integer: Including Int,short,byte,long, the initial value of 0

2, floating-point type: float,double, the initial value is 0.0

3, Character: Char, the initial value is a space, that is, "", if the output, in the console is not see the effect.

4, Boolean: Boolean, initial value is False

Basic type	Size	Minimum value	Maximum Value
Boolean	-----	-----	------
Char	16-bit	Unicode 0	Unicode 2^16-1
Byte	8-bit	-128	+127
Short	16-bit	-2^15	+2^15-1
Int	32-bit	-2^31	+2^31-1
Long	64-bit	-2^63	+2^63-1
Float	32-bit	IEEE754	IEEE754
Double	64-bit	IEEE754	IEEE754
void

Note:

In the form, ^ represents the second party;

Java uses a unicode,2 byte to represent a character.

Basic type of wrapper class

Integer, Long, short, Byte, Character, Double, Float, Boolean, BigInteger, Bigdecmail

BigInteger, BigDecimal have no corresponding basic types, mainly applied to high-precision operations, BigInteger support arbitrary precision integers,

BigDecimal supports arbitrary precision operations with decimal points.

Similarities and differences between the basic type and the packing type:

1, in Java, everything is object, but the eight basic types are not objects.

2, the Declaration of different ways, the basic type does not need to be created by the new keyword, and the package type requires the New keyword.

3, storage mode and location of the different, the basic type is the direct storage of variables stored in the stack can be efficient access, encapsulation type needs to point to the instance by reference, the specific instance is saved in the heap.

4. The initial value of the package type is NULL, the initial value of the base type depends on the specific type, for example, the initial value of the int type is 0,boolean type false;

5, the use of different methods, such as with the collection of the use of cooperation can only use the packaging type.