重学JAVA基础(五):面向对象

1.封装

import java.util.Date;

public class Human {

    protected String name;
    
    protected BirthDay birthDay;
    
    protected String sex;

    public String getName() {
        return name;
    }

    public void setName(String name) {
        this.name = name;
    }

    public String getSex() {
        return sex;
    }

    public void setSex(String sex) {
        this.sex = sex;
    }

    public BirthDay getBirthDay() {
        return birthDay;
    }

    public void setBirthDay(BirthDay birthDay) {
        this.birthDay = birthDay;
    }
    
    public int getAge(){//封装方法
        if(birthDay!=null){
            Date nowDate = new Date(System.currentTimeMillis());
            int year = nowDate.getYear()+1900;
            int month = nowDate.getMonth()+1;
            int day = nowDate.getDate();
            int age = year - this.birthDay.getYear();
            if(this.birthDay.getMonth()>month){
                return age-1;
            }else if(this.birthDay.getMonth()==month){
                if(this.birthDay.getDay()>=day){
                    return age-1;
                }
            }
            return age;
        }
        return 0;
    }
    
    public String toString(){
        return "name:"+name+" sex:"+sex+" age:"+getAge();
    }
    
    public String toString(Human human){
        return this+"";
    }

    public Human(){
        
    }
    public Human(String name,String sex) {
        super();
        this.name = name;
        this.sex = sex;
    }
    
    public Human(String sex) {
        super();
        this.sex = sex;
    }
    public Human(String name,String sex,int year,int month,int day) {
        super();
        this.name = name;
        this.birthDay = new BirthDay(year, month, day);
        this.sex = sex;
    }
    
}

public class BirthDay {

    private int year;
    
    private int month;
    
    private int day;

    public int getYear() {
        return year;
    }

    public void setYear(int year) {
        this.year = year;
    }

    public int getMonth() {
        return month;
    }

    public void setMonth(int month) {
        this.month = month;
    }

    public int getDay() {
        return day;
    }

    public void setDay(int day) {
        this.day = day;
    }
    
    public BirthDay(){
        
    }

    public BirthDay(int year, int month, int day) {
        super();
        this.year = year;
        this.month = month;
        this.day = day;
    }
    
}

2.继承

public class Woman extends Human{

    public Woman(){
        super("Woman");
    }
    
    public Woman(String name){
        super(name,"Woman");
    }
    
    public String toString(){
        return " I am Woman,"+super.toString();
    }
    
    public String toString(Woman woman){
        return woman+"";
    }
}

public class Man extends Human{

    public Man(){
        super("Man");
    }
    
    public Man(String name){
        super(name,"Man");
    }
    
    public String toString(){
        return " I am Man,"+super.toString();
    }
    
    public String toString(Man man){
        return man+"";
    }
    
}

3.多态

public class TestOO {

    public static void main(String[] args) {
        Human man = new Man("man");
        Human woman = new Woman("woman");
        System.out.println(woman.toString(man));
        System.out.println(man.toString(woman));
    }
}

运行结果：

 I am Woman,name:woman sex:Woman age:0
 I am Man,name:man sex:Man age:0