JAVA basics-differences between final and static and class loading sequence

 

I. Summary of final and static in JAVA
	Final	Static
Modifier	This class cannot be inherited	Only internal classes can be modified. This class does not require new and is statically loaded (nested top-level classes)
Modifier Interface	×	×
Modifier Constructor	×	×
Modify statement Block	×	The Virtual Machine initializes the static member field and the static statement block in the declared order.
Modify Field attributes	Attribute cannot be modified after initialization (instance constant)	Is a class variable. All instances share the variable value (class variable)
	Assign values in definitions or Constructors (each instance has a copy)
Modifier	This method cannot be overwritten (only inherited)	Yesclass method. All instances share this method (class method)
Modify function parameters	Parameter values cannot be modified by functions	×
Modifier local variable	Local variables cannot be modified after initialization (local constants)	×
Purpose	1). To prevent methods from being overwritten or rewritten;	1) define global variables or constants;
	2). Improve the running efficiency. JAVA uses an embedded mechanism for final method calls;	2). Define class methods;
Ii. JAVA class loading sequence
JAVAClass loading sequence:	1) recursively Load Static members/code blocks in the order of code, first parent class and then this class;
	2) recursively load non-static members/code blocks in the order of code, first parent class and then this class;
	3) The constructor is called recursively in the order of code, and the parent class is added to the class;
JAVAClass addition time:	1) when a static member is called, the class and parent class of the static member are loaded;
	2). Load the new object for the first time (the new object will not be loaded for the second time)
	3). The parent class will be loaded before the subclass is loaded. Members with static and final modifiers will not be loaded and used as constants;

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