尝试使用列表迭代器删除对象 [英] Trying to remove an object with list iterator

问题描述

我正在尝试使用列表迭代器从列表中删除对象.我浏览了网站上的其他解决方案，但都没有缓解错误线程"main"中的异常" java.util.ConcurrentModificationException"

I'm trying to remove an object from a list using the list iterator. I've gone through the other solutions on the website and none have alleviated the error "Exception in thread "main" java.util.ConcurrentModificationException"

这是我未执行的代码:

void PatronReturn(String bookName) {
//       get to beginning
    while(listIterator.hasPrevious()) {
        listIterator.previous();
    }
    while(listIterator.hasNext()){
        Book b = listIterator.next();
    if (listIterator.next().getBookTitle().equals(bookName)) { 
        //listIterator.next();
        //listIterator.remove();
        books.remove(b);
        //listIterator.next(); //moves to next so iterator can remove previous ?
        //books.remove(listIterator.next());; // TODO see if this is correct

    }
    }

推荐答案

1. 请勿直接从列表中删除项目.在迭代器中使用remove()方法.

您的代码也有缺陷，因为它假设还有其他列表项:

Your code is also flawed in that it assumes there are additional list items:

while(listIterator.hasNext()){
    Book b = listIterator.next();
    if (listIterator.next().getBookTitle().equals(bookName)) { 
      // eek

在这里您两次呼叫next()，但是您只呼叫了一次hasNext.也许你是说:

Here you call next() twice, yet you've only called hasNext once. Perhaps you meant:

while(listIterator.hasNext()){
    Book b = listIterator.next();
    if (b.getBookTitle().equals(bookName)) { 
      // ...

最后，您可以替换:

Finally, you can replace:

while(listIterator.hasPrevious()) {
    listIterator.previous();
}

使用

listIterator = books.listIterator();

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