Java object-oriented basis ------- (II) Package

Packaging: The class of variable privatization, does not allow direct access to external programs, use get \ set method for viewing modify operation.

Benefits: hides the implementation details of a class can only be accessed through a specific method of operating restrictions unreasonable, safer

          Reflects the relative independence of things, to avoid the influence of external operations this object,

Loosely coupled: to minimize the correlation between the objects, in order to reduce complexity and dependencies between them

step:

The main steps: 
a class attribute privatization 
added getters () of private property / the setter () method of 
setting the necessary read restriction

Visibility 1, modified properties

　　Use private variables modified so that it can only be used in this class

2, set the attribute getter () / setter () method

 

 Check required

 

 3, set the attribute storage limit

　　Attribute value validity check process to be limiting in the setter

For example: only two kinds of sex, age can not live nor too big

   public String getGender() {
        return gender;
    }

    public void setGender(String gender) {
        if(gender.equals("男")|| gender.equals("女")) {
            this.gender = gender;
        }else {
            System.out.println("冷静，性别只有男女！！！");
        }
        
    }