类不是抽象的并且不会覆盖抽象方法错误[重复]

Question

我一直在开发一个程序，它可以为学校找到多项式的根，并执行各种其他多项式相关的事情，例如将它们加在一起或找到具有给定 x 的多项式的值。虽然我制作的其他两个类工作正常（它们找到了 sin 和 cos 函数的根），但我的 FuncPoly 类似乎与我的评估方法发生了某种冲突，并且不想继承它。这是我的确切错误信息：

.\FuncPoly.java:1: 错误：FuncPoly 不是抽象的，并且不会覆盖 Function 中的抽象方法 evaluate(double) 公共类 FuncPoly 扩展 Function{

我曾尝试稍微摆弄一下评估方法并尝试添加一些覆盖，但它对我的帮助并不大。我需要帮助找出导致此错误的原因；也许它与我的构造函数有关？感谢您的阅读和帮助！代码如下；里面有很多，但我认为大部分都与问题无关。

    public abstract double evaluate(double x); //Basically just a filler for SinFunc and CosFunc

    public double findRoot(double a, double b, double epsilon){

        double x = ( a + b ) / 2;

        if (Math.abs( a - x) <= epsilon){

            return x;

        }else if (evaluate(x)*evaluate(a) >= 0){

            return findRoot(x, b, epsilon);

        }else{

            return findRoot(a, x, epsilon);
        }
    }

    public static void main(String[] args){
        //Tests SinFunc and CosFunc
        SinFunc q = new SinFunc();
        CosFunc w = new CosFunc();
        System.out.println("The root of sin(x) with the numbers entered with the given epsilon is: " + q.findRoot(3,4,.00000001));
        System.out.println("The root of cos(x) with the numbers entered with the given epsilon is: " + w.findRoot(1,3,.00000001));

        //Tests the FuncPoly stuff
        int[] test1 = {1,0,-3};
        int[] test2 = {1,-1,-2};
        FuncPoly poly1 = new FuncPoly(test1);
        FuncPoly poly2 = new FuncPoly(test2);
        System.out.println("The root of x^2 + (-3) is" + poly1.findRoot(0,10,.00000001));

    }
}

____________________________

public class FuncPoly extends Function{

    public int coefficients[];

    public FuncPoly(int[] coefficients){
        //Constructor
        this.coefficients = coefficients;
    }

    public int degree(){
        //Finds the highest power by finding the location of the last number in the array.
        return this.coefficients.length - 1;

    }

    public String toString(){
        //Converts a polynomial to a string
        StringBuilder poly = new StringBuilder();
        for(int i = degree(); i >= 0; i--){
            if (i == degree()){
                poly.append(this.coefficients[i] + "x^" + degree());
            }else{
                if (this.coefficients[i] == 0){
                    System.out.println(i);
                }else if (i == 0){
                    poly.append(" + " + this.coefficients[0]);
                } else if ( i == 1){
                    poly.append(" + " + this.coefficients[1] + "x");
                } else{
                    poly.append(" + " + this.coefficients[i] + "x^" + i);
                }
            }
        }

        return poly.toString();
    }

    public FuncPoly add(FuncPoly a){
        //Adds the selected polynomial and the last called polynomial together and returns the array.
        if (this.degree() > a.degree()){
            int[] polyAdd = new int[this.degree() + 1];
            for (int i = 0; i <= a.degree(); i++){
                polyAdd[i] = a.coefficients[i] + this.coefficients[i];
            }
            for (int i = a.degree() + 1; i < this.degree() + 1; i++){
                polyAdd[i] = this.coefficients[i];
            }
            FuncPoly polyResult = new FuncPoly(polyAdd);
            return polyResult;
        } else if (this.degree() < a.degree()){
            int[] polyAdd = new int[a.degree() + 1];
            for (int i = 0; i <= this.degree(); i++){
                polyAdd[i] = a.coefficients[i] + this.coefficients[i];
            }
            for (int i = this.degree() + 1; i < degree() + 1; i++){
                polyAdd[i] = a.coefficients[i];
            }
            FuncPoly polyResult = new FuncPoly(polyAdd);
            return polyResult;
        } else {
            int[] polyAdd = new int[a.degree() + 1];
            for (int i = 0; i < a.degree() + 1; i++){
                polyAdd[i] = a.coefficients[i] + this.coefficients[i];
            }
            FuncPoly polyResult = new FuncPoly(polyAdd);
            return polyResult;
        }
    }

    public double value(double x){
        //Finds the value of polynomial with a given x.
        double sum = 0;
        for(int i = 0; i < this.degree() + 1; i++){
            sum += this.coefficients[i] * Math.pow(x,i);
        }
        return sum;
    }

}

Answer 1

据我所知，FuncPoly 中的 value() 方法需要重命名为 evaluate() 才能成功实现来自 Function 类的抽象 evaluate() 方法。