阻塞队列BlockingQueue的add offer put，
2021-05-16 本文已影响0人
一叶知秋yi
根据个人经验，做Android开发的，可能阻塞队列使用会相对较少，但是有时候看框架源码经常会碰到，所以有必要学习一下。阻塞队列里面的几个添加和删除的方法太容易记混了，所以这里专门总结记录一下，一个是可以加深自己的记忆，另一个也可以把我的理解分享给大家。
先直接放结论，有兴趣的可以再继续往后看具体的分析
| 添加方法 | add() | offer() | put() |
|---|---|---|---|
| 添加成功 | return true | return true | 无返回 |
| 添加失败 | 抛异常 | return false | 阻塞等待直到可以插入 |
| 对应删除方法 | remove() | poll() | take() |
先讲一讲添加的几个方法，删除方案都是跟添加方法一一对应的。我们先看一下BlockingQueue中的添加方法说明
/**
* Inserts the specified element into this queue if it is possible to do
* so immediately without violating capacity restrictions, returning
* {@code true} upon success and throwing an
* {@code IllegalStateException} if no space is currently available.
* When using a capacity-restricted queue, it is generally preferable to
* use {@link #offer(Object) offer}.
*
* @param e the element to add
* @return {@code true} (as specified by {@link Collection#add})
* @throws IllegalStateException if the element cannot be added at this
* time due to capacity restrictions
* @throws ClassCastException if the class of the specified element
* prevents it from being added to this queue
* @throws NullPointerException if the specified element is null
* @throws IllegalArgumentException if some property of the specified
* element prevents it from being added to this queue
*/
boolean add(E e);
往队列中插入一个元素，插入成功则返回true，插入失败则抛出异常。
/**
* Inserts the specified element into this queue if it is possible to do
* so immediately without violating capacity restrictions, returning
* {@code true} upon success and {@code false} if no space is currently
* available. When using a capacity-restricted queue, this method is
* generally preferable to {@link #add}, which can fail to insert an
* element only by throwing an exception.
*
* @param e the element to add
* @return {@code true} if the element was added to this queue, else
* {@code false}
* @throws ClassCastException if the class of the specified element
* prevents it from being added to this queue
* @throws NullPointerException if the specified element is null
* @throws IllegalArgumentException if some property of the specified
* element prevents it from being added to this queue
*/
boolean offer(E e);
往队列中插入一个元素，插入成功则返回true，插入失败则返回false。
/**
* Inserts the specified element into this queue, waiting if necessary
* for space to become available.
*
* @param e the element to add
* @throws InterruptedException if interrupted while waiting
* @throws ClassCastException if the class of the specified element
* prevents it from being added to this queue
* @throws NullPointerException if the specified element is null
* @throws IllegalArgumentException if some property of the specified
* element prevents it from being added to this queue
*/
void put(E e) throws InterruptedException;
往队列中插入一个元素，如果队列已满会阻塞，直到队列有空余空间。
