Question

import java.util.Scanner;

public class QuadraticEquation
{
   private int a, b, c, d, s1, s2;

   public QuadraticEquation()
   {
      a = 1;
      b = 2;
      c = 1;
      d = 0;
      s1 = -1;
      s1 = -1;
   }

   public QuadraticEquation(int a, int b, int c)
   {
      this.a = a;
      this.b = b;
      this.c = c;
   }

   public int findDiscriminant(int a, int b, int c)
   {
      this.d = (int)Math.pow(b,2) - (4*a*c);
      return this.d;
   }

   public boolean equalRoots()
   {
      if (getSolution1() == getSolution2())
      {
         return true;
      } else {
         return false;
      }
   }

   public boolean noSolution()
   {
      if (Math.sqrt(this.d) == 0)
      {
         return false;
      } else {
         return true;
      }
   }

   public int getSolution1()
   {
      this.s1 = (int)(-b + Math.sqrt(this.d))/(2*a);
      return this.s1;
   }

   public int getSolution2()
   {
      this.s2 = (int)(-b - Math.sqrt(this.d))/(2*a);
      return this.s2;
   }

   public static void main (String args[])
   {
      Scanner input = new Scanner (System.in);
      for (int k = 1; k <= 3; k++)
      {
         System.out.print("Enter a, b, and c: ");
         int a = input.nextInt();
         int b = input.nextInt();
         int c = input.nextInt();

         QuadraticEquation q = new QuadraticEquation(a,b,c);

         if (q.noSolution() == true)
         {
            System.out.println("No real solution");
         } else if (q.equalRoots() == true) {
            System.out.println("The only solution is: " + q.getSolution1());
         } else {
            System.out.println("The two real solutions are: ");
            System.out.println(q.getSolution1());
            System.out.println(q.getSolution2());
         } //Else
      } //For
   } //Main
} //QuadraticEquations

我有这个代码，我试图得到一个等式的因子。如果解决方案不是整数，那么它将返回＆＃34;没有真正的解决方案＆＃34;。如果因子相同，则返回唯一因子。如果有两个因素，那么它应该返回两个因素。当只有1个因子时（例如当a = 1，b = 2和c = 1时），它起作用，但当方程不可行时，它不起作用，并且当它出现时，它就不起作用。两个解决方案，它只返回1.

这是当前不正确的输出：

 ----jGRASP exec: java QuadraticEquation
Enter a, b, and c: 1 1 1
The only solution is: 0
Enter a, b, and c: 
 ----jGRASP: process ended by user.

 ----jGRASP exec: java QuadraticEquation
Enter a, b, and c: 1 -5 6
The only solution is: 2
Enter a, b, and c: 
 ----jGRASP: process ended by user.

 ----jGRASP exec: java QuadraticEquation
Enter a, b, and c: 1 2 1
The only solution is: -1
Enter a, b, and c: 
 ----jGRASP: process ended by user.

 ----jGRASP exec: java QuadraticEquation
Enter a, b, and c: 1 -4 4
The only solution is: 2
Enter a, b, and c:

编辑：

感谢bcsb1001，我修改了我的代码，它确实有效。

import java.util.Scanner;

public class QuadraticEquation
{
   private int a, b, c, d;

   public QuadraticEquation(int a, int b, int c)
   {
      this.a = a;
      this.b = b;
      this.c = c;
      this.d = findDiscriminant(a, b, c);
   }

   public int findDiscriminant(int a, int b, int c)
   {
      return (int)Math.pow(b,2) - (4*a*c);
   }

   public boolean equalRoots()
   {
      return this.d == 0;
   }

   public boolean noSolution()
   {
      return this.d < 0;
   }

   public int getSolution1()
   {
      return (int)(-b + Math.sqrt(this.d))/(2*a);
   }

   public int getSolution2()
   {
      return (int)(-b - Math.sqrt(this.d))/(2*a);
   }

   public static void main (String args[])
   {
      Scanner input = new Scanner (System.in);
      for (int k = 1; k <= 3; k++)
      {
         System.out.print("Enter a, b, and c: ");
         int a = input.nextInt();
         int b = input.nextInt();
         int c = input.nextInt();

         QuadraticEquation q = new QuadraticEquation(a,b,c);

         if (q.noSolution() == true)
         {
            System.out.println("No real solution");
         } else if (q.equalRoots() == true) {
            System.out.println("The only solution is: " + q.getSolution1());
         } else {
            System.out.println("The two real solutions are: ");
            System.out.println(q.getSolution1());
            System.out.println(q.getSolution2());
         } //Else
      } //For
   } //Main
} //QuadraticEquations

是的，我被迫做了某些事情，比如创造＆＃34; findDiscriminant＆＃34;因为工作表强迫我。它给了我主要的方法，我应该从那里弄清楚一切。

Answer 1

您的基本代码逻辑有问题。

equalRoots()应该被称为hasOnlyOneSolution，而且应该是正确的 return this.d == 0。

noSolution()应该只是return this.d < 0。

请注意，您从不致电findDiscriminant，导致d保持为0。

这是在纸上解决此问题时所做的基本数学区别。并且必须在代码中完成相同的逻辑。

最后注意：你正在混淆字段和局部变量，比如疯狂。为什么findDiscriminant会返回一些内容并设置d。为什么它会通过a，b和c，而不是简单地访问具有相同内容的同名字段？

public class QuadraticEquation {
    private int a, b, d;

    public QuadraticEquation(int a, int b, int c) {
        this.a = a;
        this.b = b;
        this.d = b * b - (4 * a * c);
    }

    public boolean hasOnlyOneSolution() {
        return d == 0;
    }

    public boolean noSolution() {
        return d < 0;
    }

    public int getSolution1() {
        return (int) (-b + Math.sqrt(this.d)) / (2 * a);
    }

    public int getSolution2() {
        return (int) (-b - Math.sqrt(this.d)) / (2 * a);
    }

    // + your main method
}

当方程式不可用时，Java仅返回0

1 个答案: