多次更改索引值

Posted 2023-02-14

【中文标题】多次更改索引值

【英文标题】：Changing the index value multiple times

【发布时间】：2022-01-20 15:15:19

【问题描述】：

好的，所以对于学校作业，我必须制作数组并打印出数组国家/地区的索引 3 次或更多次不同的时间，我不知道该怎么做。顺便说一句，如果这有帮助，这是一个符石任务

错误：需要获取 3 个或更多不同的数字来打印所述国家/地区的索引

public class Countries

  public static void main(String[] args)
  
       // 1. Declare 4 arrays and initialize them to the given values.
       // Countries: China, Egypt, France, Germany, India, Japan, Kenya, Mexico, United Kingdom, United States
       // Capitals: Beijing, Cairo, Paris, Berlin, New Delhi, Tokyo, Nairobi, Mexico City, London, Washington D.C.
       // Languages: Chinese, Arabic, French, German, Hindi, Japanese, Swahili, Spanish, English, English
       // Filenames for map images: China.jpg, Egypt.jpg, France.jpg, Germany.jpg, India.jpg, Japan.jpg, Kenya.jpg, Mexico.jpg, UK.jpg, US.jpg
      String[] Countries = "China", "Egypt", "France", "Germany", "India", "Japan", "Kenya", "Mexico", "United Kingdom", "United States";
      String[] Capitals = "Beijing", "Cairo", "Paris", "Berlin", "New Delhi", "Tokyo", "Nairobi", "Mexico City", "London", "Washington D.C.";
      String[] Languages = "Chinese", "Arabic", "French", "German", "Hindi", "Japanese", "Swahili", "Spanish", "English", "English";
      String[] Filenames = "China.jpg", "Egypt.jpg", "France.jpg", "Germany.jpg", "India.jpg", "Japan.jpg", "Kenya.jpg", "Mexico.jpg", "UK.jpg", "US.jpg";
       // 2. Pick a random number up to the length of one of the arrays and save in the variable index
      int index = ((int)Math.random() * Capitals.length);

       // 3. Print out the info in each array using the random index
      System.out.println(Countries[index]);
      System.out.println(Capitals[index]);
      System.out.println(Languages[index]);

       // Example of showing image files using an array called images (your array name above may be different)
       // (this will only work in Active Code)
      Countries obj = new Countries();
      obj.printhtmlimage(Filenames[index]);
      

   

   // This method will just work in Active Code which interprets html
   public void printHTMLimage(String filename)
   
     String baseURL = "https://raw.githubusercontent.com/bhoffman0/CSAwesome/master/_sources/Unit6-Arrays/6-1-images/";
     System.out.print("<img src=" + baseURL + filename + ">");
   
  
  

【问题讨论】：

把代码放在一个循环中迭代3次？预期的输出是什么？

那么预期的输出应该是这个imgur.com/a/nGfdvG1

【参考方案1】：

看起来您编写的代码可以顺利通过这些步骤。如果你能够让某件事工作 1 次，但需要它发生不止一次，你将需要一个 循环。这样您就可以根据需要多次执行同一组操作。

public class Countries

  public static void main(String[] args)
  
       // 1. Declare 4 arrays and initialize them to the given values.
       // Countries: China, Egypt, France, Germany, India, Japan, Kenya, Mexico, United Kingdom, United States
       // Capitals: Beijing, Cairo, Paris, Berlin, New Delhi, Tokyo, Nairobi, Mexico City, London, Washington D.C.
       // Languages: Chinese, Arabic, French, German, Hindi, Japanese, Swahili, Spanish, English, English
       // Filenames for map images: China.jpg, Egypt.jpg, France.jpg, Germany.jpg, India.jpg, Japan.jpg, Kenya.jpg, Mexico.jpg, UK.jpg, US.jpg
      String[] Countries = "China", "Egypt", "France", "Germany", "India", "Japan", "Kenya", "Mexico", "United Kingdom", "United States";
      String[] Capitals = "Beijing", "Cairo", "Paris", "Berlin", "New Delhi", "Tokyo", "Nairobi", "Mexico City", "London", "Washington D.C.";
      String[] Languages = "Chinese", "Arabic", "French", "German", "Hindi", "Japanese", "Swahili", "Spanish", "English", "English";
      String[] Filenames = "China.jpg", "Egypt.jpg", "France.jpg", "Germany.jpg", "India.jpg", "Japan.jpg", "Kenya.jpg", "Mexico.jpg", "UK.jpg", "US.jpg";

       // Loop through this logic 3 times
       for(int i=1; i<= 3; i++)

        // 2. Pick a random number up to the length of one of the arrays and save in the variable index
        int index = ((int)Math.random() * Capitals.length);

         // 3. Print out the info in each array using the random index
        System.out.println(Countries[index]);
        System.out.println(Capitals[index]);
        System.out.println(Languages[index]);

         // Example of showing image files using an array called images (your array name above may be different)
         // (this will only work in Active Code)
        Countries obj = new Countries();
        obj.printHTMLimage(Filenames[index]);
      

   

   // This method will just work in Active Code which interprets html
   public void printHTMLimage(String filename)
   
     String baseURL = "https://raw.githubusercontent.com/bhoffman0/CSAwesome/master/_sources/Unit6-Arrays/6-1-images/";
     System.out.print("<img src=" + baseURL + filename + ">");
   
  

通过在循环中包含int index = ((int)Math.random() * Capitals.length); 行，这允许我们运行同一组指令 3 次，但每次都使用一个新的索引值。

【讨论】：

我试过你说的例子，但每次这样做，它只是一遍又一遍地具有相同的索引值。

编辑：没关系你的方式确实解决了我的问题我只需要添加一个额外的（或两个到 math.random

@ChristopherAcosta 记得接受他的回答，因为它解决了你的问题。