ArrayDeque中addfirst和offerFirst方法之间的差异 [英] Differnce between addfirst and offerFirst methods in ArrayDeque

问题描述

尝试了一个示例程序，以了解 addFirst 和 offerFirst 方法之间的区别> ArrayDeque of Java 6.但它们似乎相同，有什么建议吗？

Have tried out a sample program to understand the difference between addFirst and offerFirst methods in ArrayDeque of Java 6. But they seem to be same, any suggestions?

public void interfaceDequetest()
{
        try{
        ArrayDeque<String> ad = new ArrayDeque<String>();
        ad.addFirst("a1");
        ad.offerFirst("o1");
        ad.addFirst("a2");
        ad.offerFirst("02");
        ad.addFirst("a3");

        System.out.println("in finally block");

        for (String number : ad){
            System.out.println("Number = " + number);
        }
}

推荐答案

差异是由于队列容量限制而在添加失败时发生的情况：

The difference is what happens when the addition fails, due to a queue capacity restriction:

• .addFirst（）抛出（未经检查的）异常，


• .offerFirst（）返回 false 。

• .addFirst() throws an (unchecked) exception,
• .offerFirst() returns false.

这在 Deque ，其中 ArrayDeque implements。

This is documented in Deque, which ArrayDeque implements.

值得注意的是 ArrayDeque 没有容量限制，所以基本上 .addFirst（）永远不会抛出异常（ .offerFirst（）将始终返回 true ）;例如，这与 LinkedBlockingQueue 以初始容量构建。

Of note is that ArrayDeque has no capacity restrictions, so basically .addFirst() will never throw an exception (and .offerFirst() will always return true); this is unlike, for instance, a LinkedBlockingQueue built with an initial capacity.

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