java格式，大小数，请按百分比计息

Question

有人能解释一下它的用法吗？我真的很想知道怎么做。这是我使用Java的第二个月，请解释Java格式的用法。非常感谢你。我真的很感激。请随意问关于C++或Python的其他问题。我在格式，大小数的使用和如何设置需要帮助

import java.util.*;

import java.math.BigDecimal;

import java.text.NumberFormat;

import java.math.*;


public class Main{
    public static void main(String[] args)
    {

        Scanner myCalculation = new Scanner(System.in);

        System.out.print("Welcome to the Interest Calculator \n\n");
        String option = "y";
        while (option.equalsIgnoreCase("y"))
        {

            System.out.print("Enter Loan Amount: ");
            //double loanAmount = 520000;
            double loanAmount = myCalculation.nextDouble();
            //Get Interest rate from user
            System.out.print("Enter Interest Rate: ");
            // double interRate = .05375;
            double interRate = myCalculation.nextDouble();


            double interest = loanAmount * interRate;

            System.out.printf("%.3f", interest);
            System.out.println();


            //prompt user to continue? if he enter y then it will Continue
            //else it will stop
            //System.out.println("Continue? (y:n): ");
            Scanner scan = new Scanner(System.in);
            boolean stop = false;    
            while(!stop) {
            //do whatever
                System.out.println("Would you like to continue? (yes or no)");
                String s = scan.nextLine();
                if(s.equals("no")) {
                    stop = true;
                }
            }

        }
    }
}

Answer 1

Scanner in = new Scanner(System.in);
System.out.print("enter double");
double d = in.nextDouble(); //doubles
System.out.print("enter int");
int i = in.nextInt(); //ints

System.out.print("enter text");
String text = in.next(); //gets a string up to the first space
in.nextLine();
System.out.print("enter text w/ spaces");
String line = in.nextLine(); //gets a string up to the first space

System.out.println(d);
System.out.println(i);
System.out.println(text);
System.out.println(line);
in.close();

System.out.println(new DecimalFormat("#.###").format(4.567346344634));