多态性的使用练习

package eightdemo;
//多态的练习5

public class TestInstance {
	public static void main(String[] args) {
		TestInstance t = new TestInstance();
		t.method1(new Student());
		
		System.out.println();
		
		t.method1(new Graduate());
	}

	public void method1(Person p) {// Person p = new Student();
		System.out.println(p.getInfo());
		
		
		if (p instanceof Graduate) {
			System.out.println("a graduate");
		}

		if (p instanceof Student) {
			System.out.println("a student");
		}
		if (p instanceof Person) {
			System.out.println("a person");
		}
		
	}
}

class Person {
	protected String name = "person";
	protected int age = 50;

	public String getInfo() {
		return "Name: " + name + "\n" + "age: " + age;
	}
}

class Student extends Person {
	protected String school = "pku";

	public String getInfo() {
		return super.getInfo() + "\nschool: " + school;
	}
}

class Graduate extends Student {
	public String major = "IT";

	public String getInfo() {
		return super.getInfo() + "\nmajor:" + major;
	}
}

package eightdemo1;

public class GeometricObject {
	protected String color;
	protected double weight;
	
	protected GeometricObject(String color, double weight){
		this.color = color;
		this.weight = weight;
	}

	public String getColor() {
		return color;
	}

	public void setColor(String color) {
		this.color = color;
	}

	public double getWeight() {
		return weight;
	}

	public void setWeight(double weight) {
		this.weight = weight;
	}
	
	public double findArea(){
		return 0.0;
	}
}

package eightdemo1;

public class Circle extends GeometricObject{
	private double radius;
	
	public double getRadius() {
		return radius;
	}

	public void setRadius(double radius) {
		this.radius = radius;
	}

	public Circle(double radius,String color,double weight){
		super(color,weight);
		this.radius =radius;
	}
	
	public double findArea(){
		return Math.PI * radius * radius;
	}
	
}

package eightdemo1;

public class MyRectangle extends GeometricObject{
	private double width;
	private double height;
	
	public MyRectangle(double width,double height,String color,double weight){
		super(color,weight);
		this.width = width;
		this.height = height;
	}

	public double getWidth() {
		return width;
	}

	public void setWidth(double width) {
		this.width = width;
	}

	public double getHeight() {
		return height;
	}

	public void setHeight(double height) {
		this.height = height;
	}
	
	public double findArea(){
		return width * height;
	}
}

package eightdemo1;

public class TestGeometric {
	public static void main(String[] args) {
		TestGeometric t = new TestGeometric();
		
		Circle c1 = new Circle(2.3, "Green", 1.0);
		Circle c2 = new Circle(2.3, "Red", 1.0);
		
		MyRectangle m1 = new MyRectangle(2.3, 3.0, "blue", 2.0);
		t.displayGeometricObject(c2);
		
		
		boolean b = t.equalsArea(m1, c2);
		System.out.println(b);
	}
	
	//判断两个对象的面积是否相等
	public boolean equalsArea(GeometricObject o1,GeometricObject o2){
//		if(o1.findArea() == o2.findArea())
//			return true;
//		else 
//			return false;
		return o1.findArea() == o2.findArea();
	}
	public void displayGeometricObject(GeometricObject o){//GeometricObject o = new Circle(2.3, "Red", 1.0);
		System.out.println(o.findArea());
	}
}