java - 如何打印这个类的toString？

Question

我编写了一个多项式类和一个测试器类。当提供了次数、系数和 x 的值时，多项式类可以计算并返回多项式的和。基本上我需要编辑我的 toString 方法，以便它实际上打印出多项式

          import java.util.Arrays;
import java.util.Scanner;
public class Polynomial {

private int degree;
private int [] coefficient;
private double evaluation; 
private double sum;
private double value;
Scanner key = new Scanner(System.in);



public Polynomial(int degree)
{
    this.degree = degree;
    coefficient = new int [degree+1];

}


public void setCoefficient(int coefficient) 
{
    this.coefficient[this.degree] = coefficient;
}


public int getCoefficient(int degree)
{
    return coefficient[degree];
}



public double Evaluate(double value)
{
    this.value =value;
    for (int i=0; i<=degree; i++)
    {
        System.out.println("Enter coefficent for position " + i);
        this.coefficient[i] = key.nextInt();
        evaluation = Math.pow(value, i)*this.coefficient[0] ;
        this.sum += evaluation;

    }
        return sum;

}   






/** Standard toString method */
//needed something better than this below...needed an actual polynomial printed out 
public String toString()
{
     return "The degree of the polynomial is " + degree + " and the value for which it has been evaluated is" + value;

}
}

Answer 1

这应该符合您应该继续进行的路线。为了简单起见，我将 main 函数包含在您的 Polynomial 类中，因此如果您想将其保留在测试器类中，则必须对其进行修改。请注意，level 已被制作成大小为 level +1 的整数数组(在构造函数中分配):

import java.util.Scanner;
public class Polynomial {

private int degree;
private int [] coefficient;
private double evaluation; 
private double sum;
Scanner key = new Scanner(System.in);
public Polynomial(int degree)
{
    this.degree = degree;
    coefficient = new int [degree+1];

}

public void setCoefficient(int coefficient, int degree) 
{
    this.coefficient[degree] = coefficient;
}

public int getCoefficient(int degree)
{
    return coefficient[degree];
}

public void Evaluate(double value)
{
    for (int i=0; i<=degree; i++)
    {
        System.out.println("Enter coefficent for position " + i);
        this.coefficient[i] = key.nextInt();
        evaluation = Math.pow(value, i)*this.coefficient[0] ;
        this.sum += evaluation;

    }
}   
public double getSum(){
    return sum;
}

public String toString()
{
    String s = "";
    for (int i=0; i <= degree; i++)
    {
        s += coefficient[i];
        switch (i) {
            case 0:
                s += " + ";
                break;
            case 1:
                s += "x + ";
                break;
            default:
                s += "x^" + i + ((i==degree)?"":" + ");
        }
    }
    return s; 

}

public static void main(String[] args) {

    int degree;
    double sum;
    int coefficient;

    Scanner key = new Scanner(System.in);
    System.out.println("Enter the degree of the polynomial");
    degree=key.nextInt();

    Polynomial fun = new Polynomial(degree);



    fun.Evaluate(3.0);

    System.out.println(" The sum of the polynomial is " + fun.getSum());

    System.out.println(fun);

}

}