Java 水题系列（2）Pi的近似值

/** 

 * @Title: b.java

 * @Description: TODO

 * @author 菱形继承

 * @date 2020-03-31 03:19:34

 */



/** 

 * @ClassName: b

 * @Description: TODO

 * @author 菱形继承

 * @date 2020-03-31 03:19:34

*/



import javax.swing.*;

public class b {

    public static void main(String[] args) {

    String user_input=JOptionPane.showInputDialog("please in put an Integer n:");

    int check=Integer.parseInt(user_input);

        double pi=0;

        for(int j = 1;j <= check;j++){

            pi +=4* Math.pow(-1,j+1) / (2*j-1);

        }

        JOptionPane.showMessageDialog(null, "PI is approximately equal to: "+pi);

}

}