java基础5

• make mathods
• 主main函数，通常有5-10行代码，当代码过多时应重构，将部分内容放入不同的方法中
  重构：找概念，找重复的内容
  import java.util.Scanner;

public class Main {

public static void main(String[] args) {
    final byte percent = 100;

   int principal = (int) read("Principal: ", 1000,100000);
    float annual_rate = (float) read("Annual_rate: ",1,30);
    byte period = (byte) read("Period (Year): ",1,30);
    double res = calculateMorgage(principal,annual_rate,period);
    System.out.println("morgage: " + res);

}
public static double calculateMorgage(
        int principal,
        float annual_rate,
        byte period) {
    final byte month = 12;
    final byte percent = 100;
    float rate_month = annual_rate / month / percent;
    double res = principal * (rate_month * (Math.pow(1 + rate_month, period * month)) / (Math.pow(1 + rate_month, period * month) - 1));
    return res;
}
public static double read(String prompt,double min, double max){
    Scanner scanner = new Scanner(System.in);
    double value;
    while (true) {
        System.out.print(prompt);
        value = scanner.nextFloat();
        if (value >= min && value <= max)
            break;
        System.out.println("enter a number between"+ min + "and" + max);
    }
    return value;
}

package com.company;

import org.w3c.dom.ls.LSInput;

import java.awt.*;
import java.text.ChoiceFormat;
import java.text.NumberFormat;
import java.util.Arrays;
import java.util.Date;
import java.util.Locale;
import java.util.Scanner;

public class Main {
final static byte month = 12;
final static byte percent = 100;

public static void main(String[] args) {
    final byte percent = 100;

   int principal = (int) read("Principal: ", 1000,100000);
    float annual_rate = (float) read("Annual_rate: ",1,30);
    byte period = (byte) read("Period (Year): ",1,30);
    double res = calculateMorgage(principal,annual_rate,period);
    String mortgageFormatted = NumberFormat.getCurrencyInstance().format(res);
    System.out.println("mortgage: " + res);
    for (short m =1;m= min && value <= max)
            break;
        System.out.println("enter a number between"+ min + "and" + max);
    }
    return value;
}

}