#javaThere are only 8 basic data types, just remember them. Except these are all reference types.
javaFour categories and eight basic data types
The first category: integer typebyte short int long
Second Class: Floating point typefloat double
Category 3: Logical typeboolean(It has only two possible valuestrue false)
Category 4: Character typechar
The data that can directly allocate memory on the stack is a basic data type.
Reference data type: The reference to the data is on the stack, but its object is on the heap.
If you want to learn Java well, you must know where various data are stored in memory. Having a good understanding of memory can help you analyze programs.
Bytes:
booleanBoolean type 1/8
byteByte type 1
charCharacter type 2 One character can store one Chinese character
shortShort integer type 2
intInteger type 4
floatFloating point type (single precision) 4
longLong integer 8
double Double precision type (double precision ) 8
The default integer type in javais int type. If you want to define it asfloattype, you must add l or L after the value;
The default floating-point type is also a double-precision floating point. If you want to define it as afloattype, you must add f or F after the value.
One byte is equal to 8 bits, and one byte is equal to 256 numbers, which is -128 to 127, a total of 256.
kB means kBytes Bytes means "bytes"!
K means thousands, because the computer calculates through binary, 10 1's are exactly 1024
1111111111 (binary) = 1024 (decimal)
1Bytes (word Section) = 8bit (bit)
An English letter or an Arabic numeral is one character, occupying one byte
One Chinese character is two characters, occupying two bytes.
Generally, when talking about size, Bytes is used with a capital "B". When talking about network speed, bits are used. Note that it is a lowercase "b".
Example: A file has 8MBytes
Example: The rate at which I download files is 256KB/s, which is 2Mbit. This is usually the rate at which we use broadband Internet access.
Automatic conversion of basic data types
byte->short,char -> int -> long
float -> ; double
int -> float
long -> double
Remember: Xiao Ke If you turn large or small, you will lose accuracy! ! !
Recommended tutorial: "java tutorial"
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