System.out.print 仅限中奖线

Question

我有一个 java 彩票游戏作业，我在运行一个 while 循环以防止结果中的数字重复。我得到一个没有重复的数字列表，但是 System.out.print 返回所有行，直到我得到最后一个没有重复的行。有没有办法只打印最后的“获胜”行？

下面的代码

while (numCount<=9) {
  int randNumber = rand.nextInt(99)+1;
  if (results[0] == randNumber || results[1] == randNumber || results[2] == randNumber || results[3] == randNumber ||
        results[4] == randNumber || results[5] == randNumber || results[6] == randNumber || results[7] == randNumber 
        || results[8] == randNumber || results[9] == randNumber) {
    
  } else {
    Array.setInt(results, numCount, randNumber);
    numCount++;
  }
    
  System.out.print("The Lottery Numbers are: ");
    
  for (int i=0; i<10; i++)
      //add a 0 in front of the number is it's less that 10
    if (results[i] <10) {
      System.out.print("0"+results[i]+" ");
    }
}

Answer 1

你可以更简单地做到这一点，因为 Set 中没有重复的对象。

public static void main(String[] args) {
    Random rand = new Random();
    Set<Integer> winningNumbers = new HashSet<>();

    while (winningNumbers.size() < 9) {
        int randNumber = rand.nextInt(99) + 1;
        winningNumbers.add(randNumber);
    }

    System.out.print("The Lottery Numbers are: ");
    for (Integer number : winningNumbers) {
        //add a 0 in front of the number is it's less that 10
        if (number < 10) {
            System.out.print("0" + number + " ");
        } else {
            System.out.print(number + " ");
        }
    }
}

您甚至可以简化打印数字的方式，依靠 printf() 和 %02d，这意味着使用 0 填充作为打印数字的最大宽度 2:

public static void main(String[] args) {
    Random rand = new Random();
    Set<Integer> winningNumbers = new HashSet<>();

    while (winningNumbers.size() < 9) {
        int randNumber = rand.nextInt(99) + 1;
        winningNumbers.add(randNumber);
    }

    System.out.print("The Lottery Numbers are: ");
    System.out.printf("%02d %02d %02d %02d %02d %02d %02d %02d %02d", winningNumbers.toArray());
}

在您的代码中，只需将 System.out.print("The Lottery Numbers are: "); 行移动到 while 循环之前，将循环 for (int i=0; i<10; i++) 移动到 while 循环之后，如下所示：

System.out.print("The Lottery Numbers are: ");
while (numCount<=9) {
    int randNumber = rand.nextInt(99)+1;
    if (results[0] == randNumber || results[1] == randNumber || results[2] == randNumber || results[3] == randNumber ||
            results[4] == randNumber || results[5] == randNumber || results[6] == randNumber || results[7] == randNumber
            || results[8] == randNumber || results[9] == randNumber) {
        
    } else {
        Array.setInt(results, numCount, randNumber);
        numCount++;
    }
}

for (int i=0; i<10; i++)
    //add a 0 in front of the number is it's less that 10
    if (results[i] <10) {
        System.out.print("0"+results[i]+" ");
    }

System.out.print 仅限中奖线

System.out.print the winning line only

java

while-loop

duplicates

system.out