Java Core Technology Note five OOP

The core of Java is Object-oriented (fully object-oriented)

Object-Oriented Programming

You have to be clear about the three main features of the object

1. Behavior of the object

2. The state of the object

3. Object identification

In addition, it is necessary to understand the relationship between objects more common relationships have

Dependency Inheritance Aggregation

In Java programs, programmers should minimize the number of interdependent classes to reduce the coupling between classes.

Not all classes in Java are object-oriented features such as the Math class date class

There is an important difference between an object and an object variable

Date deadline;

This defines an object variable deadline It can refer to an object of date type But the variable deadline is not an object that is not used by the constructor to apply any date method to this variable

Java Core Technology Note five OOP