Function overloading and static keyword

* 1. Function overloading
 * Same scope (same class), same function name, different parameter list
 * this keyword:
 * ·Local variables and instance variables have a naming conflict: this.name = name;
 * ·this this( ) Call the constructor
 * Note: a. Must be located in the first line of the current valid code
 * b. This() is not allowed between constructors to call each other between constructors
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 * 2. The static keyword analysis
 * is related to the class, One class, one static member
 * Static variable Storage: Method area
 * 1)
 * ·Modified variable
 * What is the difference between static variable and instance variable?
 * Static variable One class, one static variable
 * Instance variable, one object, one instance variable
 * ·Modified method
 * The difference between static method and instance method:
 * Can this be provided
 * ·Modified class (internal class)
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 * 2) Class of Initialization sequence
 * 3) Singleton mode