从 List<Integer> 中正确删除整数 [英] Properly removing an Integer from a List&lt;Integer&gt;

问题描述

这是我刚刚遇到的一个不错的陷阱.考虑一个整数列表:

Here's a nice pitfall I just encountered. Consider a list of integers:

List<Integer> list = new ArrayList<Integer>();
list.add(5);
list.add(6);
list.add(7);
list.add(1);

对执行 list.remove(1) 时会发生什么的任何有根据的猜测?list.remove(new Integer(1)) 怎么样?这可能会导致一些令人讨厌的错误.

Any educated guess on what happens when you execute list.remove(1)? What about list.remove(new Integer(1))? This can cause some nasty bugs.

区分 remove(int index)，从给定的索引和 remove(Object o)，通过参考，在处理整数列表时?

What is the proper way to differentiate between remove(int index), which removes an element from given index and remove(Object o), which removes an element by reference, when dealing with lists of integers?

这里要考虑的要点是@Nikita提到 - 精确参数匹配优先于自动装箱.

The main point to consider here is the one @Nikita mentioned - exact parameter matching takes precedence over auto-boxing.

推荐答案

Java 总是调用最适合您的论点的方法.自动装箱和隐式向上转换仅在没有可以在没有转换/自动装箱的情况下调用的方法时执行.

Java always calls the method that best suits your argument. Auto boxing and implicit upcasting is only performed if there's no method which can be called without casting / auto boxing.

List 接口指定了两个 remove 方法(请注意参数的命名):

The List interface specifies two remove methods (please note the naming of the arguments):

• remove(Object o)
• remove(int index)

这意味着 list.remove(1) 删除位置 1 处的对象，remove(new Integer(1)) 从这份清单.

That means that list.remove(1) removes the object at position 1 and remove(new Integer(1)) removes the first occurrence of the specified element from this list.

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