Java starts from scratch four (data type)

One, Java data Type Division

ii. Basic data Types

No.	Data type	size / bit	Range of data that can be represented
1	Long (length integer)	64	-9223372036854775808 ~ 9223372036854775807
2	Int (integer)	32	-2147483648 ~ 2147483647
3	Short (shorter integer)	16	-32768~32767
4	BYTE (bit)	8	-128 ~ 127
5	char (character)	2	0 ~ 255
6	Float (single precision)	32	-3.4E38 ( -3.4´1038) ~ 3.4E38 (3.4´1038)
7	Double (dual precision)	64	-1.7E308 ( -1.7´10308) ~ 1.7E308 (1.7´10308)

Default value

No.	Data type	Default value
1	Byte	(byte) 0
2	Short	(short) 0
3	Int	0
4	Long	0L
5	Float	0.0f
6	Double	0.0d
7	Char	\u0000 (Empty, ")
8	Boolean	False

2.1. Integral typewhen the data does not have decimals or fractions, it can be declared as an integer variablesuch as: 3,-147the integral type can be divided into long,int,short and byte4 species .

         byte b=8;          short s=100;         int i=2;         long v=1000;    

2.2. Character Typethe character type occupies 2 bytes in memory and can be used to hold characters such as English letters, which are enclosed in a pair of single quotation marks (") .

         Char ch1= ' a ';         Char ch2=97;        System.out.println ("ch1=" +ch1);        System.out.println ("ch2=" +CH2);

results: Ch1=a,ch2=aA character type is also considered an integer type. commonly used escape characters:

No.	Escape character	Describe	No.	Escape character	Describe
1	\f	Page change	2	\\	Reverse Slash
3	\b	One step backwards.	4	\‘	Single quotation marks
5	\ r	Return to position	6	\"	Double quotes
7	\ t	TAB tab	8	\ n	Line break

        char ch1= ' \ ';         char ch2= ' \ \ ';        System.out.println ("ch1=" +ch1);        System.out.println ("ch2=" +CH2);        System.out.println ("\" Hello world\ "");

Results:

Ch1= "
ch2= \
"Hello World"

2.3.Floating-point type (float,double) in mathematics, these numbers with decimal points are called real numbers, and in Java, the data type is called the floating-point type, which defaults to the double type in Java.

        double num1=3.14;         float num2=7.3f;        System.out.println ("num1=" +num1);        System.out.println ("num2=" +num2);

2.4, Boolean Type (Boolean) Boolean (Boolean) type of variable, only true (true) and False (false) two. That is, when a variable is defined as a Boolean type, its value can only be true or false, except that no other value can be assigned to the variable

         booleantrue;        SYSTEM.OUT.PRINTLN ("flag =" +flag);

Results: Flag =true;

Java starts from scratch four (data type)