import javax.management.RuntimeErrorException;
interface CompareObject {
//返回0，代表相等；正数，代表当前对象大；负数代表当前对象小
public int compareTo(Object o);
}
class Circle {
//radius私有成员变量，定义了变量的get和set方法，以及空参和radius变量的两个构造器
private Double radius;
public Double getRadius() {
return radius;
}
public void setRadius(double radius) {
this.radius = radius;
}
public Circle() {
super();
}
public Circle(Double radius) {
super();
this.radius = radius;
}
}
class ComparableCircle extends Circle implements CompareObject {
public ComparableCircle(double radius) {
super(radius);
}
@Override
public int compareTo(Object o) {
if(this == o ) {
return 0;
}
else if(o instanceof ComparableCircle){
ComparableCircle c = (ComparableCircle)o;
// return (int)(this.getRadius()-c.getRadius());精度损失
// //方法2，用if比较double类型的radius的大小
// if(this.getRadius()>c.getRadius()){
// return 1;
// }
// else if(this.getRadius()<c.getRadius()) {
// return -1;
// }
// else {
// return 0;
// }
//方法3:radius声明为包装类Double类型，可以使用包装类的方法
return this.getRadius().compareTo(c.getRadius());
}
else {
// return 0;
throw new RuntimeException("传入数据类型不匹配");
}
}
}
public class ComparableCircleTest {
public static void main(String[] args) {
ComparableCircle c1= new ComparableCircle(3.4);
ComparableCircle c2 = new ComparableCircle(3.6);
int comparevalue = c1.compareTo(c2);
if(comparevalue > 0) {
System.out.println("c1大");
}
else if(comparevalue <0) {
System.out.println("c2大");
}
else if (comparevalue == 0) {
System.out.println("一样大");
}
int comparevalue2 = c1.compareTo("as");
System.out.println(comparevalue2);
}
}
