java - Java中的随机类

Question

我正在使用 Java 制作一个预订系统，我想创建随机 ID 号。 (我要展示的代码并不是我的类中的所有代码，它只是相关的内容。)

我命名了一个字段 randomGenerator，它是一个 Random 对象，并在我的构造函数中声明了它:

public class ReservationSystem {
     private Random randomGenerator;

     public ReservationSystem() {
           randomGenerator = new Random();
     }

然后这是我遇到困难的方法:

     public void generateCustomerID(String id, int numbersInID) {
     //incNumber stands for incremented number
     int incNumber = 1;
     //create a new array of numbers as big as the user has defined
     int[] numbers = new int[numbersInID];
     while(numbersInID < (incNumber +1)) {
         //add a new number to the array between 0 and 10
         numbers[incNumber] = randomGenerator.nextInt(10);
         incNumber++;
     }
     System.out.print(id);
     for(int number: numbers)
         System.out.print(number);
 }

在我的应用程序中，我给出了这些值:

  public class Application { 
       public static void main(String[] args) {
               reserve.generateCustomerID("AB-", 3);
        }
  }

我已经收到输出AB-000。

Answer 1

• 在 Java 中，数组的索引从 0 开始，而不是 1。
• 条件numbersInID < (incNumber +1)是错误的，当numbersInID时循环体不会被执行是 3。

试试这个:

public void generateCustomerID(String id, int numbersInID) {
    //incNumber stands for incremented number
    int incNumber = 0;
    //create a new array of numbers as big as the user has defined
    int[] numbers = new int[numbersInID];
    while(incNumber < numbersInID) {
        //add a new number to the array between 0 and 10
        numbers[incNumber] = randomGenerator.nextInt(10);
        incNumber++;
    }
    System.out.print(id);
    for(int number: numbers)
        System.out.print(number);
}