The difference between static variables and member variables:
A: Different ownership
Static variables: belong to classes, class variables
Member variables: belong to objects, object variables, Instance variables
B: Different memory locations
Static variables: Static area of method area
Member variables: Heap memory
C: Different life cycles
Static variables: Static variables are loaded as the class is loaded, and disappear as the class disappears
Member variables: Member variables exist with the creation of the object, and disappear as the object Disappear and disappear
D: Call different
Static variables: can be called through the object name, or can be called through the class name
Member variables: can only be called through the object name
The difference between member variables and local variables:
A: Different locations in the class
Member variables: outside the methods in the class
Local variables: In the method definition or method declaration
B: Different locations in memory
Member variables: in heap memory
Local variables: in stack memory
C: Different life cycles
Member variables: exist with the creation of the object, and disappear with the disappearance of the object
Local variables: exist with the call of the method, and disappear with the invocation of the method The method disappears after the call is completed
D: Different initialization values
Member variables: have default initialization values
Local variables: no default initialization values, must be defined, assigned, and then can be used.
Note:
The local variable name can be the same as the member variable name. When used in a method, the proximity principle is adopted.
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