package Rational; public class RationalNum {
 private int molecule;
 private int denominator;  public RationalNum(int molecule,int denominator) {
  this.molecule = molecule;
  this.denominator = denominator;
  if(this.denominator==0) { //分母为0时需要强制退出；
   throw new IllegalArgumentException("分母不可为0！");
  }
 }
 public int getNumerator() {
  return molecule;
 }
 public void setNumerator(int molecule) {
  this.molecule = molecule;
 }
 public int getDenominator() {
  return denominator;
 }
 public void setDenominator(int denominator) {
  this.denominator = denominator;
 }
 public int gcd() { // 约分
  int t, m, n;
  m = this.denominator;
  n = this.molecule;
  if (n == 0) {
   return 0;
  }
  while (m % n != 0) {
   t = n;
   n = m % n;
   m = t;
  }
  this.denominator /= n;
  this.molecule /= n;
  return n;
 }  public RationalNum add(RationalNum num) { // 加法
  int numerator, denominator;
  denominator = num.denominator * this.denominator;
  numerator = num.denominator * this.molecule + num.molecule * this.denominator;
  RationalNum result = new RationalNum(numerator, denominator);
  result.gcd();
  return result;
 }
 public RationalNum subtraction(RationalNum num) { // 减法
  int numerator, denominator;   denominator = num.denominator * this.denominator;
  numerator = this.molecule * num.denominator - num.molecule * this.denominator;
  RationalNum result = new RationalNum(numerator, denominator);
  result.gcd();
  return result;
 }
 public RationalNum multiply(RationalNum num) { // 乘法   int numerator = this.molecule * num.molecule;
  int denominator = this.denominator * num.denominator;
  RationalNum result = new RationalNum(numerator, denominator);
  result.gcd();
  return result;
 }
 public RationalNum division(RationalNum num) { // 除法
  if (num.molecule != 0) {
   int denominator = this.denominator * num.molecule;
   int numerator = this.molecule * num.denominator;
   RationalNum result = new RationalNum(numerator, denominator);
   result.gcd();
   return result;
  } else
   throw new IllegalArgumentException("除数不可为0！");
 }
 public RationalNum abs() { // 绝对值
  int d,m;
  if (this.denominator < 0) d = -this.denominator;
  else d = this.denominator;
  
  if (this.molecule < 0) m = -this.molecule;
  else m = this.molecule;
  RationalNum result = new RationalNum(m, d);
  return result;
 }
 public boolean equals(RationalNum num) { //是否相等；
  RationalNum temp1 = new RationalNum(this.molecule, this.denominator);
  RationalNum temp2 = new RationalNum(num.molecule, num.denominator);
  temp1.gcd();
  temp2.gcd();
  if (temp1.denominator == temp2.denominator && temp1.molecule == temp2.molecule) return true;
  else return false;
 }
 public double doubleValue() {
  return (double) this.molecule / this.denominator;
 }
 public int intValue() {
  return this.molecule / this.denominator;
 }
 public String toString() {
  if(this.molecule==0)return 0+"";
  else if(this.denominator==1)return this.molecule+"";
  else if(this.denominator==-1)return "-"+this.molecule;
  else return this.molecule + "/" + this.denominator;
 }
}

1.与c语言的有理数代码相比较,为什么你设计的类更加面向对象?
c语言更偏于面向过程，着重强调运算过程，而Java则是面向对象，对于对象进行一系列操作，编写类，方便对象使用 2.尝试从代码复用的角度来描述你设计的有理数类 别人如何复用你的代码？直接把代码发给别人，或者打包成.jar供别人使用 3.别人的代码是否依赖你的有理数类的内部属性?当你的有理数类的属性修改时,是否会影响他人调用你有理数类的代码? 依赖于有理数内部属性，因为代码并不没有面向所有情况而写，有理数的输入是有一定条件的；
属性修改后，可能是另一种计算情况。 4.有理数类的public方法是否设置合适?为什么有的方法设置为private? 设置为public，就是为了方便其他包使用；
设置为private是为了实现数据封装，不让别人用或者修改你的数据,比较安全。