Different levels by access control: public - protected - default - privateProtected and default differences are accessible to subclasses outside the same package, protected is accessible, default is not. Inheritance remembers a general rule: unloading methods in Java and more stringent methods more stringent than initial methods, but it can make it more publicized. Such as: Declaration in the superclass as a method of public, in all subclasses must be public (Most methods in the applet) declared that private methods cannot be inherited. For the above, if you have to access a private variable, you can use SetXX, getxx to access it. The value of the final variable cannot be changed, and it is often known as a constant Final method.
