The difference between object-oriented _ member variables and local variables

Scope of Action:

A local variable acts in a function or statement (defined in a function or statement (such as a for statement) and must be initialized)

Member variables are scoped to the entire class (defined in the class, with default initialization values, you can define display initialization values)

In-memory location:

The member variable is in heap memory. Because the object exists, it exists in memory.

Local variables are in the stack memory.

If the member variable does not have a defined display initialization, then the system is initialized by default (the variables in the heap memory will have default initialization values)
BYTE 0
Short 0
int 0
Long 0L
Double 0.0D
Float 0.0f
Boolean false
Reference data type default initialization value is NULL

1  Public classVariabledemo {2      Public Static voidMain (string[] args) {3Car c=NewCar ();4C.color= "Blue";5 C.run ();6     }7 }8 classcar{9     //member variables, defined in the class, acting on the entire class, have default initialization values. (can define display initialization)TenString color= "Red"; One     intNum=4; A     //member functions -     voidrun () { -System.out.println (color+ "...." +num); the     } -}

 1  class   car{ 2  String color= "Red" ; 3   4  void   run () { 6  int  num = 9; //  in the member is accessed. 7  System.out.println (color+ ".... +num");  8   9  }

One class accesses a non-static member in another class, the class object must be created

1 classperson{2     intAge ;3      Public voidShurt () {4         intAge = 89;//Local variables must be initialized5System.out.println (age);//because there is an age variable in the function, access is accessed at the time of the Shurt function, and the external member variable is hidden.6     }7 }8 //method of Java recycling mechanism: Finalize ();9 //the method of waking up the Java recycle mechanism is System.GC (); (Calling the method Java virtual machine does not necessarily perform garbage collection immediately)

1  Public classVariableTest2 {2      Public Static voidMain (string[] args) {3         intx = 5;4 Change (x);5 System.out.println (x);6     }7      Public Static intChangeintx) {8         returnx = 4;9     }Ten } One //The result is still 5, because X is a local variable, and when the change method is executed, the X in the Change method is released, which is not the same as the X in the main method.

The difference between object-oriented _ member variables and local variables