JAVA程序设计-有理数类的设计

JAVA程序设计-有理数类的设计

1.有理数类代码

package rationalNumber;

public class Rational {// 类中含有方法
	private int numerator; // 分子
	private int denominator; // 分母

	public int getNumerator() { // 获取分子
		return numerator;
	}

	public int getDenominator() { // 获取分母
		return denominator;
	}

	public Rational() { // 构造方法
		this.numerator = 0;
		this.denominator = 1;
	}

	public Rational(int x) { // 传入参数为整数时，构造有理数
		if (x < 0) {
			this.numerator = -x; // 分子为正数
			this.denominator = -1;
		} else {
			this.numerator = x;
			this.denominator = 1;
		}
	}

	public Rational(int numerator, int denominator) { // 参数为两整数，以分数形式构造有理数
		if (denominator == 0) {
			System.out.println("错误，分母不能为零！");
			System.exit(0);
		} else if (numerator == 0) {
			this.numerator = 0;
			this.denominator = denominator;
			return;
		}
		int numMax = getNumMax(numerator, denominator);// numMax为分子分母的最大公约数

		this.numerator = numerator / numMax;
		this.denominator = denominator / numMax;
	}

	public Rational(Double x) { // 参数含有小数点时构造有理数
		int flag = 0;
		if (x < 0) {
			flag = 1;
			x = -x;
		}
		String str = x.toString(); // 把小数分割成两部分
		String[] st = new String[2];
		st = str.split("\.");

		int numOne = (int) (Integer.parseInt(st[0]) * Math.pow(10, st[1].length()) + Integer.parseInt(st[1])); // 小数化为分数时的分子
		int numTwo = (int) Math.pow(10, st[1].length()); // 小数化为分数时的分母
		int numMax = getNumMax(numOne, numTwo);

		this.numerator = numOne / numMax;
		if (flag == 1) { // 小数为负数
			this.denominator = (-1) * numTwo / numMax;
		} else {
			this.denominator = numTwo / numMax;
		}
	}

	private int getNumMax(int a, int b) { // 获取最大公约数
		int temp;
		temp = a % b;
		while (temp != 0) {
			a = b;
			b = temp;
			temp = a % b;
		}
		return b;
	}

	public Rational add(Rational anOther) { // 相加运算
		int numOne = anOther.numerator * this.denominator + anOther.denominator * this.numerator; // 相加所得分数的分子
		int numTwo = anOther.denominator * this.denominator; // 相加所得分数的分母

		Rational result = new Rational(numOne, numTwo);
		return result;
	}

	public Rational minus(Rational anOther) { // 相减运算
		int numOne = this.numerator * anOther.denominator - this.denominator * anOther.numerator; // 相减所得分数的分子
		int numTwo = anOther.denominator * this.denominator; // 相减所得分数的分母

		Rational result = new Rational(numOne, numTwo);
		return result;
	}

	public Rational multiply(Rational anOther) { // 相乘运算
		int numOne = anOther.numerator * this.numerator; // 相乘所得分数的分子
		int numTwo = anOther.denominator * this.denominator; // 相乘所得分数的分母

		Rational result = new Rational(numOne, numTwo);
		return result;
	}

	public Rational divide(Rational anOther) { // 相除运算
		int numOne = this.numerator * anOther.denominator; // 相除所得分数的分子
		int numTwo = this.denominator * anOther.numerator; // 相除所得分数的分母

		Rational result = new Rational(numOne, numTwo);
		return result;
	}

	public Rational abs() { // 取绝对值
		int numOne, numTwo;
		if (this.numerator < 0) {
			numOne = -this.numerator;
		} else {
			numOne = this.numerator;
		}
		if (this.denominator < 0) {
			numTwo = -this.denominator;
		} else {
			numTwo = this.denominator;
		}

		Rational result = new Rational(numOne, numTwo);
		return result;
	}

	public Rational getPow(Rational number, int n) { // 获取有理数number的n次方
		int numOne = number.numerator;
		int numTwo = number.denominator;
		for (int i = 1; i < n; i++) {
			numOne = numOne * number.numerator;
			numTwo = numTwo * number.denominator;
		}

		Rational result = new Rational(numOne, numTwo);
		return result;
	}

	public Rational remain(Rational number) { // 取余
		if (this.divide(number).denominator == 1) { // 能够整除
			Rational result = new Rational(0, 1);
			return result;
		}

		Rational result;
		if (this.divide(number).denominator == this.denominator * number.numerator) {
			result = new Rational(this.numerator * number.denominator, 1);
		} else {
			result = new Rational(this.numerator, 1);
		}
		return result;
	}

	public void compare(Rational number) { // 比较大小
		if (number.judgeSign().equals("此有理数是正数") && this.judgeSign().equals("此有理数是负数")) {
			System.out.println(number.toString() + "更大");
		} else if (number.judgeSign().equals("此有理数是负数") && this.judgeSign().equals("此有理数是正数")) {
			System.out.println(this.toString() + "更大");
		} else { // 两个有理数同号
			if (number.toDouble() == this.toDouble()) {
				System.out.println("两个有理数大小相等");
			} else if (number.toDouble() > this.toDouble()) {
				System.out.println(number.toString() + "更大");
			} else if (number.toDouble() < this.toDouble()) {
				System.out.println(this.toString() + "更大");
			}
		}
	}

	public String judgeSign() { // 判断有理数的正负性
		String str = "";
		if (this.numerator == 0) {
			str = "此有理数为0";
		}
		if ((this.numerator < 0 && this.denominator < 0) || (this.numerator > 0 && this.denominator > 0)) {
			str = "此有理数是正数";
		} else if (this.denominator < 0 || this.numerator < 0) {
			str = "此有理数是负数";
		}
		return str;
	}

	public int toInt() { // 有理数转化为int类型
		return (int) this.numerator / this.denominator;
	}

	public double toDouble() { // 有理数转化为double类型
		return (double) this.numerator / this.denominator;
	}

	public String toString() // 转化为字符串
	{
		Rational num = new Rational(0, 1);
		String str = new String();
		num.numerator = this.numerator;
		num.denominator = this.denominator;
		if (num.numerator * num.denominator < 0) {  // 有理数为负数
			str = str + "-";
		}
		num = abs();
		if (num.denominator == 1) {
			str = str + num.numerator;
		} else {
			str = str + num.numerator + "/" + num.denominator;
		}

		return str;

	}

}

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2.实现及测试代码

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2.1 结果如下：

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3. 尝试描述怎么与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?

• 新建一个对象（类的实例）时，此对象具有相应的属性，可以调用设计的类中的方法。而C语言中的有理数代码会更注重于函数的设计，更注重于编译过程中对于每个函数模块的调用，而不是面向对象的属性和方法进行相应的处理。

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4. 尝试从代码复用的角度来描述你设计的有理数类。从几个方面讨论。

4.1 别人如何复用你的代码?

• 只需要在程序开头加上语句"import rationalNumber.Rational;"，通过import关键字导入包rationalNumber中的类Rational。

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4.2 别人的代码是否依赖你的有理数类的属性?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?

• 会依赖有理数类的属性；会影响他人调用有理数类的代码，比如类中构造时，参数若改变，那么就要输入不同的参数。

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4.3 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?

• 合适，这样不同包中的其他类也可以调用有理数类；因为他人无需访问此方法，比如求最大公约数的方法getNumMax，他人调用有理数类时，创建对象时，无需访问此方法，只需要了解构造方法就行。