Java语言实现分数的加减乘除

Java语言实现分数的加减乘除

Java：

import java.util.Scanner;

class Fraction{    // 分数类
	public int molecule, denominator;   // 分子, 分母
	public Fraction() {
		molecule = 1;
		denominator = 1;
	}
}

public class TestFive {
	private static Fraction a, b;   // 两个分数
	static Scanner sc = new Scanner(System.in);
	
	// 最大公约数方法
	public static int greatestCommonDivisor(int a, int b) {     
		return (a % b == 0) ? b : greatestCommonDivisor(b, a%b); 
	}
	// 最小公倍数
	public static int leastCommonMultiple(int a, int b) {
		return a*b/greatestCommonDivisor(a, b);
	}
	
	// 加法
	public static Fraction add(Fraction a, Fraction b) {
		Fraction result = new Fraction();               // 计算结果
		// 通分并计算
		int denleacommul = leastCommonMultiple(a.denominator, b.denominator);   // 两个分数的分母的最小公倍数
		int temp1 = denleacommul/a.denominator;         
		int temp2 = denleacommul/b.denominator;
		result.molecule = a.molecule*temp1 + b.molecule*temp2;        // 分子相加
		result.denominator = denleacommul;                            // 分母不变
		// 约分
		int moldengrecomdiv = greatestCommonDivisor(Math.abs(result.molecule), Math.abs(result.denominator));// 不考虑符号
		result.denominator /= moldengrecomdiv;
		result.molecule /= moldengrecomdiv;
		// 返回结果
		return result;
	}
	// 减法
	public static Fraction subtraction(Fraction a, Fraction b) {
		Fraction result = new Fraction();               // 计算结果
		// 通分并计算
		int denleacommul = leastCommonMultiple(a.denominator, b.denominator);   // 两个分数的分母的最小公倍数
		int temp1 = denleacommul/a.denominator;         
		int temp2 = denleacommul/b.denominator;
		result.molecule = a.molecule*temp1 - b.molecule*temp2;        // 分子相减
		result.denominator = denleacommul;                            // 分母不变
		// 约分
		int moldengrecomdiv = greatestCommonDivisor(Math.abs(result.molecule), Math.abs(result.denominator));// 不考虑符号
		result.denominator /= moldengrecomdiv;
		result.molecule /= moldengrecomdiv;
		// 返回结果
		return result;
	}
	// 乘法
	public static Fraction multiplication(Fraction a, Fraction b) {
		Fraction result = new Fraction();               // 计算结果
		// 计算
		result.molecule = a.molecule*b.molecule;
		result.denominator = a.denominator*b.denominator;
		// 约分
		int moldengrecomdiv = greatestCommonDivisor(Math.abs(result.molecule), Math.abs(result.denominator));// 不考虑符号
		result.denominator /= moldengrecomdiv;
		result.molecule /= moldengrecomdiv;
		// 返回结果
		return result;
	}
	// 除法
	public static Fraction division(Fraction a, Fraction b) {
		Fraction result = new Fraction();               // 计算结果
		// 计算
		result.molecule = a.molecule*b.denominator;
		result.denominator = a.denominator*b.molecule;
		if(result.denominator < 0) {                    // 分母不为负的
			result.molecule = -result.molecule;
			result.denominator = -result.denominator;
		}
		// 约分
		int moldengrecomdiv = greatestCommonDivisor(Math.abs(result.molecule), Math.abs(result.denominator));// 不考虑符号
		result.denominator /= moldengrecomdiv;
		result.molecule /= moldengrecomdiv;
		// 返回结果
		return result;
	}
	
	// 读取分子和分母
	public static void inputMolDen(Fraction a) {
		a.molecule = 0;
		a.denominator = 0;
		String inputfraction = sc.next();
		
/*      	
 * 		boolean flag = true;          // 标记符号
 *		int count = -1;               // count为负是读分子，count为正时读分母
 *		for(int i = 0;i < inputfraction.length();i++) {
 *			if(inputfraction.charAt(i) == '-')        // 如果分数是负的, flag 标记为 false
 *				flag = false;
 *			else if(Character.isDigit(inputfraction.charAt(i)) && count < 0){
 *				if(count != -1) 
 *					a.molecule *= 10;
 *				count--;
 *				a.molecule += Integer.valueOf(String.valueOf(inputfraction.charAt(i)));
 *			}else if(inputfraction.charAt(i) == '/') {    // 分子读完, 变 count 为正, 读分母
 *				count = 1;                               
 *			}else if(count > 0){
 *				if(count != 1) 
 *					a.denominator *= 10;
 *				count++;
 *				a.denominator += Integer.valueOf(String.valueOf(inputfraction.charAt(i)));
 *			}
 *		}
 *      // 处理符号
 *		if(flag == false) 
 *			a.molecule = -a.molecule;
 *	
 *	    以上注释代码也可以实现下面功能	
 */
		
		boolean flag = true;          // 标记符号
		int molstart = 0, molend = 0, i = 0;
		while(i < inputfraction.length()) {        // 找分子的开头
			if(Character.isDigit(inputfraction.charAt(i))){
				molstart = i;
				break;
			}
			i++;
		}
		for(i =0;i < inputfraction.length();i++) {
			if(inputfraction.charAt(i) == '-')        // 如果分数是负的, flag 标记为 false
				flag = false;
			if(inputfraction.charAt(i) == '/') {
				molend = i;        // 分子的末尾 + 1
				break;
			}
		}
		a.molecule = Integer.parseInt(inputfraction.substring(molstart, molend));
		a.denominator = Integer.parseInt(inputfraction.substring(molend+1, inputfraction.length()));
		
		// 处理符号
		if(flag == false) 
			a.molecule = -a.molecule;
	}
	
	// 分数字符串
	public static String stringFraction(Fraction a) {
		if(a.denominator == 1)     // 分母为 1
			return String.valueOf((a.molecule));
		else
			return (a.molecule + "/" + a.denominator);
	}
	
	public static void main(String[] args){
		try {
			a = new Fraction();
			System.out.print("a = ");
			inputMolDen(a);     // 输入 a
			
			b = new Fraction();
			System.out.print("b = ");
			inputMolDen(b);     // 输入 b
			
			System.out.println("a+b = " + stringFraction(add(a, b)));
			
			System.out.println("a-b = " + stringFraction(subtraction(a, b)));
			
			System.out.println("a*b = " + stringFraction(multiplication(a, b)));
			
			System.out.println("a/b = " + stringFraction(division(a, b)));
			
		}catch(ArithmeticException e) {
			System.out.println("分母出现零");
		}
	}

}
/* Code Running Results
a = 1/3
b = -1/2
a+b = -1/6
a-b = 5/6
a*b = -1/6
a/b = -2/3
*/