Java 从抽象类扩展并实现可比较接口时出错
尽管GeometricObject没有错误,但GeoCircle显示一个错误,表示GeoCircle不是抽象的,并且不会覆盖抽象方法compareTo(GeometricObject),尽管compareTo方法不是作为抽象类编写的 //实现可比较接口的抽象类GeometricObjectJava 从抽象类扩展并实现可比较接口时出错,java,Java,尽管GeometricObject没有错误,但GeoCircle显示一个错误,表示GeoCircle不是抽象的,并且不会覆盖抽象方法compareTo(GeometricObject),尽管compareTo方法不是作为抽象类编写的 //实现可比较接口的抽象类GeometricObject public abstract class GeometricObject implements Comparable<GeometricObject> { public String
public abstract class GeometricObject implements Comparable<GeometricObject>
{
public String name;
//sample abstract class of getting area of various shapes
public abstract double getArea();
//sample abstract class for getting perimeter/circumference of various shapes
public abstract double getPerimeter();
//pass in and return name of the object selected in a system out line
public void name(String n)
{
System.out.println("This is a " + n);
}
/** A method for comparing the areas of two geometric objects and returning a boolean for their equals */
public static boolean equalArea(GeometricObject object1,GeometricObject object2)
{
//comparing double to another double
return object1.getArea()==object2.getArea();
}
// a method to find the bigger between two GeometricObjects and returning a String statement
public static void max(GeometricObject g1, GeometricObject g2)
{
if(g1.compareTo(g2)>0)
System.out.println("Object 1 is larger ");
else if (g1.compareTo(g2)<0)
System.out.println("Object 2 is larger ");
else
System.out.println("Objects are the same ");
}
// an override of the compareTo method from the implemented comparable interface
public int compareTo(GeometricObject g1, GeometricObject g2)
{
if(g1.getArea()>g2.getArea())
return 1;
else if (g1.getArea()<g2.getArea())
return -1;
else
return 0;
}
}
//a class for calculating circumference and area of a circle extended from GeometricObject
public class GeoCircle extends GeometricObject implements Comparable<GeoCircle>
{
public String name;
public double radius;
//constructor for only inputting radius of the circle
public GeoCircle(double r)
{
radius = r;
}
// 2ndconstructor taking a name for the shape and radius of the circle
public GeoCircle(String n, double r)
{
name = n;
radius = r;
}
//method to get area of the shape with previously passed in radius
public double getArea()
{
return Math.PI*Math.pow(radius,2);
}
//method to get circumference of the circle with radius previously given
public double getPerimeter()
{
return 2*Math.PI*radius;
}
//a compareTo method
public int compareTo(GeoCircle obj)
{
if (this.getArea() > obj.getArea())
return 1;
else if (this.getArea() < obj.getArea())
return -1;
else
return 0;
}
}
公共抽象类GeometricObject实现了
{
公共字符串名称;
//获取各种形状区域的示例抽象类
公共抽象双getArea();
//用于获取各种形状的周长/周长的示例抽象类
公共抽象双GetPermiture();
//传入并返回在系统输出行中选择的对象的名称
公共无效名称(字符串n)
{
System.out.println(“这是一个”+n);
}
/**一种比较两个几何对象面积并为其相等值返回布尔值的方法*/
公共静态布尔equalArea(GeometricObject对象1、GeometricObject对象2)
{
//把双倍与另一个双倍进行比较
返回object1.getArea()==object2.getArea();
}
//查找两个GeometricObject之间的较大值并返回String语句的方法
公共静态最大无效空间(几何对象g1、几何对象g2)
{
如果(g1.与(g2)>0相比)
System.out.println(“对象1较大”);
else if(g1.compareTo(g2)g2.getArea())
返回1;
else if(g1.getArea()obj.getArea())
返回1;
else if(this.getArea()
作为参考,添加@Override注释可验证一个方法是否正确重写了一个超类方法,该超类方法可能已被捕获
作为参考,添加@Override注释可验证一个方法是否正确重写了一个超类方法,该超类方法可能已被捕获。您应该在基类中使用泛型:
public abstract class GeometricObject<T extends GeometricObject> implements Comparable<T> {
...
// an override of the compareTo method from the implemented comparable interface
public int compareTo(T that) {
if(this.getArea()>that.getArea())
return 1;
else if (this.getArea()<that.getArea())
return -1;
else
return 0;
}
}
//a class for calculating circumference and area of a circle extended from GeometricObject
public class GeoCircle extends GeometricObject<GeoCircle> {
...
@Override // Remove this method if it doesn't differ from parent implementation
public int compareTo(GeoCircle that) {
...
}
}
class GeometricObjectAreaComparator implements Comparator<GeometricObject> {
@Override
public int compare(GeometricObject o1, GeometricObject o2) {
...
}
}
公共抽象类GeometricObject实现了{
...
//从实现的可比较接口重写compareTo方法
公共整数比较(T){
如果(this.getArea()>that.getArea())
返回1;
else如果(this.getArea()您应该在基类中使用泛型:
public abstract class GeometricObject<T extends GeometricObject> implements Comparable<T> {
...
// an override of the compareTo method from the implemented comparable interface
public int compareTo(T that) {
if(this.getArea()>that.getArea())
return 1;
else if (this.getArea()<that.getArea())
return -1;
else
return 0;
}
}
//a class for calculating circumference and area of a circle extended from GeometricObject
public class GeoCircle extends GeometricObject<GeoCircle> {
...
@Override // Remove this method if it doesn't differ from parent implementation
public int compareTo(GeoCircle that) {
...
}
}
class GeometricObjectAreaComparator implements Comparator<GeometricObject> {
@Override
public int compare(GeometricObject o1, GeometricObject o2) {
...
}
}
公共抽象类GeometricObject实现了{
...
//从实现的可比较接口重写compareTo方法
公共整数比较(T){
如果(this.getArea()>that.getArea())
返回1;
else if(this.getArea())它看起来像任何两个GeometricObjects
都可以通过面积进行比较,而不仅仅是圆对圆。它看起来像任何两个GeometricObjects
都可以通过面积进行比较,而不仅仅是圆对圆。这是一个非常糟糕的主意-可比较的接口需要'e1.compareTo(e2)'==0 e1。等于(e2)“。你的解决方案打破了这一合同-圆圈和正方形可以有相等的面积,但它们不相等。我同意@ursa在这一点上的观点。最好有一个单独的比较器来进行面积比较。另一方面,如果这是一个课堂作业,并且讲师告诉他们这样做,你就不会有太多问题了。”可以。除了可能重写equals
作为区域比较。这是一个非常糟糕的主意-可比较接口需要'e1.compareTo(e2)==0 e1.equals(e2)“。你的解决方案打破了这一合同-圆圈和正方形可以有相等的面积,但它们不相等。我同意@ursa在这一点上的观点。最好有一个单独的比较器来进行面积比较。另一方面,如果这是一个课堂作业,并且讲师告诉他们这样做,你就不会有太多问题了。”可以。除了可能覆盖equals
作为区域比较。