Java 只有 returns 0 当方程不可因式分解时

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

我有这段代码，我正在尝试获取方程式的因式。如果解不是整数，那么它 returns "No real solution"。如果因素相同，那么它 return 是唯一的因素。如果有两个因素，那么它应该 return 两个因素。它在只有 1 个因子时起作用（例如，当 a=1、b=2 和 c=1 时），但当方程不可因式分解时不起作用，并且当有两个解时，它只有 returns 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：

多亏了 bcsb1001，我修改了我的代码，它可以工作了。

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

顺便说一句，我被迫做某些事情，例如创建 "findDiscriminant"，因为工作表迫使我这样做。它给了我主要的方法，我应该从那里弄清楚一切。

Answer 1

你的基本代码逻辑有问题。

equalRoots() 应该叫做 hasOnlyOneSolution 并且应该正好是
return this.d == 0.

noSolution() 应该只是 return this.d < 0.

请注意，您从不调用findDiscriminant，这会导致d保持为0。

这是您在纸上解决此问题时所做的基本数学区分。并且必须在代码中完成完全相同的逻辑。

最后说明：您疯狂地混淆了字段和局部变量。为什么 findDiscriminant return 和设置 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
}

Java 只有 returns 0 当方程不可因式分解时

Java only returns 0 when equation is unfactorable

java

equation

formula

quadratic