9.7 Summary

1, the process of thinking: to achieve the function of every detail.

2, the structure of thought: divided into responsibilities, plate.

3. object: Object is a concrete entity, with clearly defined characteristics and behavior "Everything is object, object because of my concern",

4, Object-oriented: a way of understanding things, pay attention to the overall understanding of things, the most consistent with the natural thinking of human logic habits.

5. Class:

6. A class is a set of objects that have the same properties and behaviors, and a class is an abstraction of an object that is an instance of a class.

7, attributes are the characteristics of the object, each object has its own independent property values, the property of an object changes, does not affect the properties of another object, the property is a variable encapsulated in the object, is a member of the object, the property is also called the member variable

8. Null indicates that a variable does not point to any object, that is, a call to null for a property and method that does not hold any object address of R , throws a null pointer exception.

9, if an object is not pointed to by the variable, then the object is eligible for garbage collection.

10. Static variables are variables shared by all objects, so you can pass the class name . access, static variables are also called class variables.

11 . The difference between a static variable and a member variable.

12, member variables are part of an object, each object has a different member variable, and when an object member variable is changed, no other objects are affected.

13, static variables independent of the object, many objects share a static variable, when the static variable changes, will affect all objects.

14, static variables load the machine before the object, and the member variables with the production of the object.

15. member variable access can only be accessed through the object . Access , while static variables can be accessed through the (object . ) and (class name . ) in a way.

9.7 Summary