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java - 在 Java 中查找和编辑 ArrayList

问题描述

我编写了一个代码来将用户提供的每个约会日历存储到一个 ArrayList 中。每个 ArrayList 包含标题、描述、日期和时间。

现在我想为用户提供一个选项来编辑他们选择的约会日历的数据。

我使用约会日历的标题进行比较。这是代码：

// Asks user to enter the Appointment title that they wish to edit
System.out.println("Please enter the appointment that you wish to edit: ");
String choicetitle = scan.next();

for (Appointment value : aplist)
{
    // if the title of the Appointment matches with one of the data, then..
    if (choicetitle.equalsIgnoreCase(value.title))
    {

        // ..the output occurs on the console and asks the user to enter the new data
        input = new Scanner(System.in);

        System.out.println("Please give the new data: \n");
        System.out.println("Please give the date of the appointment! \n" +
                "Year (format YYYY): ");
        year = input.nextInt();
        System.out.println("Month (format MM): ");
        month = input.nextInt();
        System.out.println("Day (format DD): ");
        day = input.nextInt();
        value.date = LocalDate.of(year, month, day);

        System.out.println("Please give the time of the appointment! \n" +
                "Hour (format hh): ");
        hour = input.nextInt();
        System.out.println("Minute (format mm): ");
        min = input.nextInt();
        value.time = LocalTime.of(hour, min);

        System.out.println("Please give the title of the appointment: ");
        value.title = input.next();

        System.out.println("Please give the description of the appointment: ");
        value.desc = input.next();
    }
    // if the user enters a title that doesn't exist
    else
    {
        System.out.println("There's no appointment with this title!");
    }
}

但是如果 ArrayList 中已经有 3 个元素（3 个约会日历）并且假设我要编辑第三个元素，它会给出以下输出：

  There's no appointment with this title!
  There's no appointment with this title!
  Please give the new data:
  Please give the date of the appointment!
  Year (format YYYY):

有什么办法可以输出：

  1. 仅当用户给出的标题与 ArrayList 中的标题之一匹配时才给出扫描仪方法，
  2. 当用户输入的标题与 ArrayList 中的任何标题都不匹配时，只给出一个“此标题没有约会”？

提前致谢！

标签： javafor-loopif-statementarraylist

解决方案

看来您对调试代码的过程并不熟悉。所有计算机程序员都需要知道如何做到这一点。如果您使用的是IDE，那么它可能有一个调试器。你应该学习如何使用它。

您正在for循环中进行所有处理。for您应该首先通过循环找到请求的约会。循环终止后for，只有当您找到了请求的约会时，您才应该处理它。这是一些帮助您入门的代码。

System.out.println("Please enter the appointment that you wish to edit: ");
String choicetitle = scan.next();
Appointment found = null;
for (Appointment value : aplist)
{
    // if the title of the Appointment matches with one of the data, then..
    if (choicetitle.equalsIgnoreCase(value.title))
    {
        found = value;
        break;
    }
}
if (value == null) {
    System.out.println("There's no appointment with this title!");
}
else {
    System.out.println("Please give the new data: \n");
    System.out.println("Please give the date of the appointment! \n" +
                "Year (format YYYY): ");
    year = scan.nextInt(); // no need to create a separate `Scanner`
    // rest of your processing code
}

或者，您可以使用流 API，尽管我认为您还没有了解这一点。下面的代码显示了如何使用流 API搜索特定约会。

aplist.stream()
      .filter(value -> choicetitle.equalsIgnoreCase(value.title))
      .findFirst();

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