有理数类

 1 public class Rational {

 2

 3     private int numerator;

 4     private int denominator;

 5

 6     public Rational(int aNumerator, int aDenominator){

 7         int r = gcd(aDenominator, aNumerator);

 8         numerator = aNumerator / r;

 9         denominator = aDenominator / r;

10         sign();

11     }

12

13     private static int gcd(int a, int b){

14         if(b == 0){

15             return a;

16         }

17         else{

18             return gcd(b, a % b);

19         }

20     }

21

22     private void sign(){

23         if(denominator < 0){

24             numerator = -numerator;

25             denominator = -denominator;

26         }

27     }

28

29     public Rational plus(Rational b){

30         int d = this.denominator * b.denominator;

31         int n = this.numerator * b.denominator + b.numerator * this.denominator;

32         return new Rational(n, d);

33     }

34

35     public Rational minus(Rational b){

36         int d = this.denominator * b.denominator;

37         int n = this.numerator * b.denominator - b.numerator * this.denominator;

38         return new Rational(n, d);

39     }

40

41     public Rational times(Rational b){

42         int d = this.denominator * b.denominator;

43         int n = this.numerator * b.numerator;

44         return new Rational(n, d);

45     }

46

47     public Rational divides(Rational b){

48         return times(new Rational(b.denominator, b.numerator));

49     }

50

51     public boolean equals(Object b){

52         if(this == b)return true;

53         if(b == null)return false;

54         if(this.getClass() != b.getClass())return false;

55

56         Rational that = (Rational)b;

57         if(this.numerator == that.numerator && this.denominator == that.denominator)return true;

58         return false;

59     }

60

61     public String toString(){

62         return this.numerator + "/" + this.denominator;

63     }

64

65     public static void main(String[] args) {

66         Rational a = new Rational(8, 30);

67         Rational b = new Rational(32, 40);

68         System.out.println("a = " + a);

69         System.out.println("b = " + b);

70         System.out.println("a + b = " + a.plus(b));

71         System.out.println("a - b = " + a.minus(b));

72         System.out.println("b - a = " + b.minus(a));

73         System.out.println("a * b = " + a.times(b));

74         System.out.println("a / b = " + a.divides(b));

75         System.out.println("b / a = " + b.divides(a));

76         System.out.println("a == b? " + (a.equals(b) == true? "true":"false"));

77     }

78

79 }

有理数类