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java如何实现分数

2026-03-25 18:03:12Java

Java实现分数类的方法

在Java中实现分数（Fraction）类需要处理分数的基本运算（加减乘除）、约分、比较等操作。以下是实现分数类的核心步骤：

定义分数类的基本结构

public class Fraction {
    private int numerator;   // 分子
    private int denominator; // 分母

    public Fraction(int numerator, int denominator) {
        if (denominator == 0) {
            throw new IllegalArgumentException("分母不能为零");
        }
        this.numerator = numerator;
        this.denominator = denominator;
        simplify(); // 构造时自动约分
    }
}

实现约分方法

约分需要使用最大公约数（GCD）算法：

java如何实现分数

private void simplify() {
    int gcd = gcd(Math.abs(numerator), Math.abs(denominator));
    numerator /= gcd;
    denominator /= gcd;

    // 确保分母始终为正
    if (denominator < 0) {
        numerator *= -1;
        denominator *= -1;
    }
}

// 计算最大公约数的欧几里得算法
private int gcd(int a, int b) {
    return b == 0 ? a : gcd(b, a % b);
}

实现基本运算方法

// 加法
public Fraction add(Fraction other) {
    int newNumerator = numerator * other.denominator + other.numerator * denominator;
    int newDenominator = denominator * other.denominator;
    return new Fraction(newNumerator, newDenominator);
}

// 减法
public Fraction subtract(Fraction other) {
    int newNumerator = numerator * other.denominator - other.numerator * denominator;
    int newDenominator = denominator * other.denominator;
    return new Fraction(newNumerator, newDenominator);
}

// 乘法
public Fraction multiply(Fraction other) {
    return new Fraction(numerator * other.numerator, denominator * other.denominator);
}

// 除法
public Fraction divide(Fraction other) {
    return new Fraction(numerator * other.denominator, denominator * other.numerator);
}

重写toString方法

@Override
public String toString() {
    if (denominator == 1) {
        return Integer.toString(numerator);
    }
    return numerator + "/" + denominator;
}

实现比较方法

@Override
public boolean equals(Object obj) {
    if (!(obj instanceof Fraction)) return false;
    Fraction other = (Fraction) obj;
    return numerator == other.numerator && denominator == other.denominator;
}

// 可以进一步实现Comparable接口
public int compareTo(Fraction other) {
    int left = numerator * other.denominator;
    int right = other.numerator * denominator;
    return Integer.compare(left, right);
}

使用示例

public class Main {
    public static void main(String[] args) {
        Fraction f1 = new Fraction(3, 4);
        Fraction f2 = new Fraction(2, 5);

        System.out.println(f1.add(f2));      // 输出: 23/20
        System.out.println(f1.subtract(f2)); // 输出: 7/20
        System.out.println(f1.multiply(f2)); // 输出: 3/10
        System.out.println(f1.divide(f2));   // 输出: 15/8
    }
}