Introduction to java data types

Data type

Basic data type

• Numeric type

• Integer type (byte, short, int, long )

• Character type (char)

• Boolean type (boolean)

Reference data type

• Class

• Interface

• Array

Note: For example, the String type is also a class type.

Features

1. Conceptually
Basic type: variable name points to a specific value
Reference type: variable name points to the memory address of the data object
2. From the perspective of memory construction
Basic type: Java will allocate memory space to the variable immediately after it is declared
Reference type: No memory is allocated when the variable is declared, but a memory address is stored
3. From the aspect of use
Basic type: When using, you need to assign a specific value, and when judging, use the "==" sign
Reference type: When using, you can assign null. When judging, use the equals method

Basic data type byte length

##short2byte(bit)1char2boolean1float4double8

Data type	byte
long	8
int	4

NoteThe char type in java is stored in Unicode encoding. Can store Chinese characters.

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