【Java学习笔记】多态数组

多态数组

使用场景：数组的定义类型为父类类型，里面保存的实际元素类型为子类类型

举例应用

建立父类 person，子类 student，teacher，boss，设置共有方法say()，用for 循环遍历数组，使用instance of判断并调用独有的方法

代码示例

//父类
package polyarry;public class person {int age;String name;public person(){}public person(int age, String name) {this.age = age;this.name = name;}public void say(){System.out.println("我是person类");}
}//子类
package polyarry;public class student extends person{double score;public student(int age, String name, double score) {super(age, name);this.score = score;}public void say(){System.out.println("student类\nage:" + age +"\nname:" + name + "\nscore:" + score+ "\n===============");}public void learn(){System.out.println("调用student类的learn()方法~~我的分数是：" + score);}
}package polyarry;public class teacher extends person{public teacher(int age, String name) {super(age, name);}public void say(){System.out.println("teacher类\nage:" + age +"\nname:" + name + "\n===============");}public void teach(){System.out.println("调用teacher类的teach()方法~~");}}package polyarry;public class boss extends person{public boss(int age, String name) {super(age, name);}public void say(){System.out.println("boss类\nage:" + age +"\nname:" + name+ "\n===============");}public void conference(){System.out.println("调用boss类的conference()方法~~");}
}// 主类
package polyarry;public class main {public static void main(String[] args) {person[] p = new person[4];p[0] = new student(18, "jackson", 95.5);p[1] = new teacher(35, "smith");p[2] = new boss(26, "天霸");p[3] = new student(18, "tom", 65);//由于是父类指向子类，需要向下转型System.out.println("首先调用所有类的say方法" + "\n===============");for (int i = 0; i < p.length; i++) {p[i].say();}System.out.println("遍历每一个子类对象，调用独有的方法\n");for (int i = 0; i < p.length; i++) {if (p[i] instanceof student) {student stu = (student) p[i];stu.learn();}else if(p[i] instanceof teacher){teacher tech = (teacher) p[i];tech.teach();}else if(p[i] instanceof boss){boss bos = (boss) p[i];bos.conference();}else{System.out.println("你的类型不正确");}}}
}//运行结果
首先调用所有类的say方法
===============
student类
age:18
name:jackson
score:95.5
===============
teacher类
age:35
name:smith
===============
boss类
age:26
name:天霸
===============
student类
age:18
name:tom
score:65.0
===============
遍历每一个子类对象，调用独有的方法调用student类的learn()方法~~我的分数是：95.5
调用teacher类的teach()方法~~
调用boss类的conference()方法~~
调用student类的learn()方法~~我的分数是：65.0