简单了解Java多态向上转型相关原理

package com.my.pac14;

/**
 * @auther Summerday
 */
public class DynamicBinding {
  //Object是所有类的超类，根据向上转型，该方法可以接受任何类型的对象
  public static void test(Object x) {
    System.out.println(x.toString());
  }

  public static void main(String[] args) {
    test(new PrimaryStudent());//Student
    test(new Student());//Student
    test(new Person());//Person
    test(new Object());//java.lang.Object@1b6d3586
  }
}

class Person extends Object {
  @Override
  public String toString() {
    return "Person";
  }
}

class Student extends Person {
  @Override
  public String toString() {
    return "Student";
  }
}

class PrimaryStudent extends Student {
}

 public static void test(Object x) {
    System.out.println(x.toString());
  }

public static void main(String[] args) {
  test(new PrimaryStudent());//Student
  test(new Student());//Student
  test(new Person());//Person
  test(new Object());//java.lang.Object@1b6d3586
}

Object x = new Student();

// 原来的情况：需要创建很多很多的测试方法。
  public static void test(Object x) {
    System.out.println(x.toString());
  }
  public static void test(Person x) {
    System.out.println(x.toString());
  }
  public static void test(Student x) {
    System.out.println(x.toString());
  }
  public static void test(PrimaryStudent x) {
    System.out.println(x.toString());
  }