多态

多态是父类的引用指向了自己的子类对象。

当调用方法时，会根据实际的对象去调用方法

总结：变量在编译阶段绑定，方法在运行阶段绑定。属性不能重写，方法可以重写。 

public class Father { 
    
    public void method() { 
       System.out.println("父类方法，对象类型：" + this.getClass()); 
    } 
    
} 

public class Son extends Father { 
    
    public void method() {   
           System.out.println("子类方法，对象类型：" + this.getClass());   
    }   
    
    public static void main(String[] args) { 
       Father sample = new Son();//向上转型 
       sample.method(); 
    } 
} 

 

父类和子类有相同的属性时

public class Person {

    public String name;

    public String getName() {
        return name;
    }

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

public class Student  extends Person {

    public String name;

    public String getName() {
        return name;
    }
    
    public Student(String name) {
        this.name = name;
        super.name = "wangwu";
    }
    
    public static void main(String[] args) {
       
        Person person =  new Student("zhangsan");
        System.out.println(person.name);   //wangwu
        
        System.out.println("****************");
        Student student_1 = new Student("zhangsan");
        Person person_1  = student_1;
        System.out.println("person_1.getName() :" + person_1.getName()); //zhangsan
        System.out.println("person_1.name :"+ person_1.name); //wangwu
        System.out.println("student_1.getName() :" + student_1.getName());//zhangsan
        System.out.println("student_1.name :" + student_1.name);//zhangsan
       
    }
    
}