java - 单击时如何更改 jButton 值

Question

我在编译时不断收到错误。

我不知道如何使用列表生成的整数并在单击后将其显示到 jButtons 中。

 public static void Random ()
{
    int Rand [] = new int [49];
    for (int b = 0; b < 49; b++)
        Rand [b] = b;

    List<Integer> alist = Arrays.stream(Rand)
                                        .boxed()
                                        .map (x -> x + 1)
                                        .collect (Collectors.toList());                                 

    Collections.shuffle(alist);
}

private class HandleTextField implements ActionListener
{   
   @Override
   public void actionPerformed(ActionEvent event)
   {
       for (int a = 0; a < 49; a++)
       {
        if (event.getSource() == jbArray[a]) 
        {
            //error on this line "alist cannot be resolved to a variable"
            jbArray[a].setText(alist);
        }   
     }
   }
} 

Answer 1

所以，你有两个问题:

1. alist 只能在 Random 方法中访问，因为它是一个局部变量并且是在那里声明的。为了解决这个问题，你需要使用更大的范围声明 alist here是局部变量的解释。

2. setText 需要 String 类型输入，而 alist 不是字符串而是列表。如果你想访问 alist 的元素，那么你可以使用 alist.get(yourIndex);

   static List<Integer> alist; //is not in random method so it can be accessed by other methods
   public static void Random ()
   {
   int Rand [] = new int [49];
   for (int b = 0; b < 49; b++)
       Rand [b] = b;
   
   alist = Arrays.stream(Rand)
                                       .boxed()
                                       .map (x -> x + 1)
                                       .collect (Collectors.toList());                                 
   
   Collections.shuffle(alist);
   }
   
   
   private class HandleTextField implements ActionListener
   {   
      @Override
      public void actionPerformed(ActionEvent event)
      {
          for (int a = 0; a < 49; a++)
          {
           if (event.getSource() == jbArray[a]) 
           {
               jbArray[a].setText(alist.get(a)+"");//uses only the element you want rather than all of the list
           }   
        }
      }
   }
   

希望这对您有帮助!