Question

我的代码的目的是编写一个程序，使用Rational类计算以下求和系列：1/2 + 2/3 + 3/4 + ... + 99/100。

我的代码如下所示：

import java.math.BigInteger;
public class Exercise {
    public static void main(String[] args){

        final BigInteger N = new BigInteger("99");
        RationalV8 sum = new RationalV8();

        for (BigInteger i = BigInteger.ONE; i.compareTo(N) <= 0; i = i.add(BigInteger.ONE)){

            sum = sum.add(new RationalV8(i, i.add(BigInteger.ONE)));
        }

        System.out.println("The sum : " + sum + " = "
            + sum.doubleValue());

  }
}

class RationalV8 extends Number implements Comparable <RationalV8>{

    private BigInteger numerator = BigInteger.ZERO;
    private BigInteger denominator = BigInteger.ONE;

    public RationalV8(){
        this(BigInteger.ZERO, BigInteger.ONE);
    }

    public RationalV8( BigInteger numerator, BigInteger denominator){
        BigInteger gcd  = gcd(numerator, denominator);
        if (denominator.compareTo(BigInteger.ZERO) < 0 ){

            this.numerator = numerator.multiply(new BigInteger("-1")).divide(gcd);

        } else {
            this.numerator = numerator.divide(gcd);
        }

        this.denominator = denominator.abs().divide(gcd);
    }


    public static BigInteger gcd(BigInteger n, BigInteger d){
        BigInteger n1 = n.abs();
        BigInteger n2 = d.abs();

        BigInteger gcd = BigInteger.ONE;

        for (BigInteger i = BigInteger.ONE; i.compareTo(n1) <= 0 && i.compareTo(n2) <= 0;
                        i = i.add(BigInteger.ONE) ){

            if (n1.remainder(i).equals(BigInteger.ZERO) && n2.remainder(i).equals(BigInteger.ZERO)){
            gcd = i;
            }
        }
        return gcd; 
    }


    public BigInteger getNumerator(){
        return numerator;
    }

    public BigInteger getDenominator(){
        return denominator;
    }

    public RationalV8 add(RationalV8 secondRational){
        BigInteger n = numerator.multiply(secondRational.getDenominator()).add(
                denominator.multiply(secondRational.getNumerator()));
        BigInteger d = denominator.multiply(secondRational.getDenominator());
        return new RationalV8(n, d);
    }


    public RationalV8 subtract(RationalV8 secondRational){

        BigInteger n = numerator.multiply(secondRational.getDenominator()).subtract(
                       denominator.multiply(secondRational.getNumerator()));

        BigInteger d = denominator.multiply(secondRational.getDenominator());
        return new RationalV8(n, d);
    }

    public RationalV8 multiply(RationalV8 secondRational){

        BigInteger n = numerator.multiply(secondRational.getNumerator());

        BigInteger d = denominator.multiply(secondRational.getDenominator());
        return new RationalV8(n, d);
    }

    public RationalV8 divide(RationalV8 secondRational){
        BigInteger n = numerator.multiply(secondRational.getDenominator());

        BigInteger d = denominator.multiply(secondRational.getNumerator());
        return new RationalV8(n, d);
    }

    @Override
    public int compareTo(RationalV8 o){
        if ( (this.subtract((RationalV8) o)).getNumerator().compareTo(BigInteger.ZERO) > 0){
            return 1;
        } 
    else if ( (this.subtract((RationalV8) o)).getNumerator().compareTo(BigInteger.ZERO) < 0){
            return -1;
        } else {
            return 0;
        }
    }

    @Override
    public String toString(){

        if (denominator.equals(BigInteger.ONE)){
            return numerator + " ";
        } else {
            return numerator + "/" + denominator;
        }
    }

   @Override
   public boolean equals(Object param1){

       if ((this.subtract( (RationalV8) (param1) )).getNumerator().equals(BigInteger.ZERO) ){
           return true;
       } else {
           return false;
       }
   }

  @Override
  public int hashCode(){
      return new Double( this.doubleValue() ).hashCode();
  }

  //@Override
  public int intValue(){
      return (int)doubleValue();
  }

  //@Override
  public float floatValue(){
      return (float)doubleValue();
  }

  public double doubleValue(){
      return numerator.doubleValue() / denominator.doubleValue();
  }

  public long longValue(){
      return (long)doubleValue();
  } 
}

此代码的运行输出为：第一个系列的总和是1/0 =无穷大。

但由于整数溢出，输出不正确。

谁能告诉我问题出在哪里？

Answer 1

我认为BigInteger n2 = n.abs();行应该是BigInteger n2 = d.abs();。我不确定这是唯一的错误。

如何解决这个1/0（无穷大）？

1 个答案: