java 面向对象实例——近似求π

代码如下： 

import java.util.Scanner;

public class Js {

	double num = 0;

	public void pai() {
		Scanner input = new Scanner(System.in);
		int n = input.nextInt();
		for (int i = 1; i <= n; i++) {
			if (i % 2 == 1)
				num += 4 * (1.0 / (2 * i - 1));
			else
				num -= 4 * (1.0 / (2 * i - 1));

		}
		System.out.print(num);
	}

	public static void main(String[] args) {
		Js H = new Js();
		H.pai();
	}
}

运行结果：

输入：1000

输出：3.140592653839794