Basic knowledge of Java ignored (II.)

14. The contents of the string cannot be changed, and the character value of a subscript cannot be modified. The "+" connection between strings is pointed to by the reference address in the stack that modifies the variable by "disconnect-reconnect."

15. When an object is instantiated as an argument to an array, class (which can have a string in a property of a class), the value of the original main method changes when the method changes it.

When the string class variable is a parameter, the value is modified in the method, and the original string value does not change, because the value of the string type is changed by referring to the heap address, and the original heap content exists.

16. This keyword: Represents a property in a class, invokes a method, or constructs a method (placed in the first row), representing the current object.

17. This accesses the properties in this class, the methods in this class, or the properties or methods in the parent class if none is present in this class.

18. Memory areas commonly used in Java:

A stack of memory space: the name of the object where it was saved (or the address where the heap memory was saved)

b Heap Memory Space: Save the actual contents of each object

C Global Data area: Save properties of static type

D Global Code: Save All Method definitions

19. A method other than a static declaration can invoke a property or method of a static declaration, but a method or property declared by a static can only be invoked by the methods or properties of the static declaration.

20, System.exit (1) means to exit the system, the exit () method adds a number other than 0 to exit the system.

21. Code BLOCK: You can access the properties (including private) or methods in this class by means of a section of code enclosed in {}.

Common code blocks:

Basic knowledge of Java ignored (II.)