将arraylist中的每个数字相乘

Question

编写一个允许用户输入多个值的程序，然后该程序应该将以磅（GBP）输入的值转换为多种不同的货币。菜单应该是这个样子：

1. 输入值和类型-1停止
2. 欧元
3. 美元
4. 日元
5. 卢比
6. 退出

2时，3，4或5被选中时，程序应该显示在原磅和公司中输入的每个值兑换货币，以及所有数字和兑换总数。

public class Money { 
    public static void main(String[] args) { 
     System.out.println("Enter values and type -1 to stop"); 
     System.out.println("'1' = Euros"); 
     System.out.println("'2' = Dollars"); 
     System.out.println("'3' = Yen"); 
     System.out.println("'4' = Rupees"); 
     System.out.println("'5' = Exit"); 

     int count=0; 
     String exit = "-1", euro="E"; 

     Scanner scan = new Scanner(System.in); 

     System.out.println(); 
     System.out.print("Convert to: "); 

     while (!scan.hasNext("[E, D, Y, R, X]+")) { 
      System.out.print("Invalid value, enter Surname again: "); 
      scan.next(); 
     } 

     String exTo = scan.next(); 

     ArrayList<String> num = new ArrayList<String>(); 

     while (true) { 
      count++; 
      System.out.print("|| Enter values "+count+" in (P)Pounds : "); 

      while (!scan.hasNextDouble()) { 
       System.out.print("Invalid value, try again: "); 
       scan.next(); 
      } 
      num.add(scan.next()); 

      if(num.contains(exit)){ 
       String ar[]=num.toArray(new String[num.size()]); 
       ar=num.toArray(ar); 

       System.out.println("Result: "+ num); 

       scan.close(); 
       break; 
      } 
     } 
    } 
} 

Answer 1

试试这个：

import java.util.*; 
class Money { 
    public static void main(String[] args) { 
     System.out.println("Enter values and type -1 to stop"); 
     System.out.println("'1' = Euros"); 
     System.out.println("'2' = Dollars"); 
     System.out.println("'3' = Yen"); 
     System.out.println("'4' = Rupees"); 
     System.out.println("'5' = Exit"); 
    int count=0; 
    String exit = "-1", euro="E"; 

    Scanner scan = new Scanner(System.in); 

    System.out.println(); 
    System.out.print("Convert to: "); 

    while (!scan.hasNext("[E, D, Y, R, X]+")) { 
     System.out.print("Invalid value, enter Surname again: "); 
     scan.next(); 
    } 

    String exTo = scan.next(); 

    ArrayList<String> num = new ArrayList<String>(); 

    while (true) { 
     count++; 
     System.out.print("|| Enter values "+count+" in (P)Pounds : "); 

     while (!scan.hasNextDouble()) { 
      System.out.print("Invalid value, try again: "); 
      scan.next(); 
     } 
     num.add(scan.next()); 

     if(num.contains(exit)){ 
      for(int i=0;i<num.size();i++){ 
      num.set(i,Integer.toString((Integer.parseInt(num.get(i))*2))); 
      } 
      System.out.println("Result: "+ num); 

      scan.close(); 
      break; 
     } 
    } 
} 
} 

删除最后输入（-1）

打印前加入这一行num.remove("-1");

Answer 2

如何繁殖内部数组列表中的每个号码像用户输入 阵列中的数字列表数组看起来像这样：[20，30，40]和 后我需要像每个数字结果显示通过乘以用于 实施例2 [40，60，80]

如何围绕通过该列表循环，并执行计算？

for (Integer i : yourList) 
    i *= 2; 

或者你可以尝试番石榴，Lists.transform(list, func)如果你想做更复杂的计算。

http://docs.guava-libraries.googlecode.com/git/javadoc/com/google/common/collect/Lists.html#transform(java.util.List，com.google.common.base.Function）