java - 在获得所需值后尝试使用break退出for循环 - 总是抛出异常

Question

我有一个 for 循环，用于遍历数组列表，一旦找到我需要的对象，我想在该对象的 set 方法中设置先前获得的对象，为“未找到”设置一个标志为 false，然后跳出循环。之后，如果未找到标志仍然为真，我想抛出异常，否则只是到达方法的末尾。

我认为我要么滥用了break，要么滥用了for循环。我不断地抛出异常。

注意，“items”是 LibraryItems 的数组列表。

        for(LibraryItem l : items) {
        if(l.equals(item)) {
            l.setCheckedOut(patronToRetrieve);
            itemNotFound = false;
            break;
        } else {
            itemNotFound = true;
        }
    }
        if (itemNotFound = true) {
            throw new CheckInOutException("The item " + item.getTitle() + " does not exist in the catalogue. Sorry, " + patronToRetrieve.getName() + ", you will not be able to check this out at this time.");
        } else {

        }

Answer 1

我看到的一个问题是:

if (itemNotFound = true) {
            throw new CheckInOutException("The item " + item.getTitle() + " does not exist in the catalogue. Sorry, " + patronToRetrieve.getName() + ", you will not be able to check this out at this time.");
        } 

以上语句的结果始终为 true，因为您在 if 子句中将 true 分配给 itemNotFound。

应该是:

if (itemNotFound) {
            throw new CheckInOutException("The item " + item.getTitle() + " does not exist in the catalogue. Sorry, " + patronToRetrieve.getName() + ", you will not be able to check this out at this time.");
        } 

(或)

 if (itemNotFound == true) {
                throw new CheckInOutException("The item " + item.getTitle() + " does not exist in the catalogue. Sorry, " + patronToRetrieve.getName() + ", you will not be able to check this out at this time.");
            } 

== 是相等性检查，= 是赋值。