java - 在 Java 中循环后，跟踪文件中字符串出现的时间将不起作用

Question

我正在介绍 CS 课程，我必须从文件中提取字符串并打印该字符串在文件中的次数。它的那部分工作正常。问题是我们必须循环它以让它通过相同的过程处理尽可能多的字符串。当我将计算字符串在文件中的次数的变量计数器重置为 0 时，输出显示该变量为 0。它被初始化为 0，所以我看不到循环后发生了什么变化。

while (answer) {
    int timesUsed = 0;  for (int i = 0; i < monAr.length; ++i) {
        while (monFile.hasNext()) {
            monAr[i] = monFile.next();

            if (monAr[i].equalsIgnoreCase(desiredTag)) {
                timesUsed = timesUsed + 1;
            }
        }
    }
    System.out.println("On Monday, #" + desiredTag + " appeared " + timesUsed + " times "+ "and was " + (((float) timesUsed / monAr.length) * 100) + "% of all hashtags used for the day."); 
    System.out.print("Do you want to search another hashtag (y/n)? ");
    choice = scnr.nextLine();

    if (choice.equals("n")) {
     answer = false;
   }
}

Answer 1

问题是您正在使用 aScanner来读取文件，但是如果您需要重新扫描，则指针已经在文件的末尾。

您需要在while循环开始的正下方实例化您的扫描仪：

Scanner monFile;
While(answer) {
    monFile = new Scanner(new File(“test/Monday”));
    ...
}

Answer 2

您可以有另一个变量，例如totalUses将存储每次迭代的结果：

int totalUses = 0;
while (answer) {
    int timesUsed = 0;  
    for (int i = 0; i < monAr.length; ++i) {
        while (monFile.hasNext()) {
            monAr[i] = monFile.next();

            if (monAr[i].equalsIgnoreCase(desiredTag)) {
                timesUsed = timesUsed + 1;
            }
        }
    }
    System.out.println("On Monday, #" + desiredTag + " appeared " + timesUsed + " times "+ "and was " + (((float) timesUsed / monAr.length) * 100) + "% of all hashtags used for the day."); 
    System.out.print("Do you want to search another hashtag (y/n)? ");
    choice = scnr.nextLine();

    if (choice.equals("n")) {
     answer = false;
   }
   totalUses += timesUsed;
}
System.out.println("Total uses : "+ totalUses);