三角形1是抽象；无法实例化“驱动程序错误

Question

遇到无法被实例化的问题，甚至扩展和尝试重写它，都无法修复它。尝试使用一个驱动程序文件和两个其他文件打印结果回来。卡住了一段时间，任何事情都很感激。

公共抽象类Triangle extends Lot实现可比较的 {

public abstract double calculateArea();

public abstract String getID();

public int compareTo(LotType1 o) {
    if (calculateArea() > o.calculateArea()) {
        return 1;
    } else if (calculateArea() < o.calculateArea()) {
        return -1;
    } else {
        return 0;
    }
}

@Override 
public String toString() {
    return "Lot ID: " + getID()
            + " Area: " + calculateArea();
}

}

驱动程序文件=====

公共类测试批{

public static void main（String args[]){

Lot[] lots = {new Triangle1("L1",350, 200) {},
              new Triangle2("L2",100,270),
              new Triangle1("L3",100, 270),
              new Triangle2("L4",350,200)
             };


java.util.Arrays.sort(lots);

// print out sorted results
for (Lot lot: lots) {
  System.out.print(lot + " "); 
  System.out.println();
}

Answer 1

无法启动抽象类。根据需要，首先从类实现中删除abstract关键字。然后，创建一个构造函数来获取您的3个参数，实现CalculateArea和GetID这两个方法。请尝试从下面的代码开始

import java.util.Comparator;

public class Triangle implements Comparator<Triangle> {
    private String id;

    public Triangle(String id) {
        this.id = id;
    }


    public double calculateArea() {
        int area = 0;
        //calculate your area
        return area;
    }

    public String getID() {
        return id;

    }

    @Override
    public String toString() {
        return "Triangle ID: " + getID()
                + " Area: " + calculateArea();
    }

    @Override
    public int compare(Triangle t1, Triangle t2) {
        if (t1.calculateArea() > t2.calculateArea()) {
            return 1;
        } else if (t1.calculateArea() < t2.calculateArea()) {
            return -1;
        } else {
            return 0;
        }
    }
}