项目代码优化(四)

• 场景

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• 解释

• 英文

       Early classes of the Java API, such as Vector, Hashtable and StringBuffer, were synchronized  to make them thread-safe. Unfortunately, synchronization has a big negative impact on performance,  even when using these collections from a single thread.  It is better to use their new unsynchronized replacements:  ArrayList or LinkedList instead of Vector Deque instead of Stack HashMap instead of Hashtable StringBuilder instead of StringBuffer Noncompliant Code Example Vector cats = new Vector(); Compliant Solution ArrayList cats = new ArrayList(); Exceptions Use of those synchronized classes is ignored in the signatures of overriding methods.  @Override public Vector getCats() {...}

• 中文

  1.早期类的java API，如向量、哈希表和StringBuffer是同步的使它们线程安全。不幸的是，同步对性能有很大的 负面影响，甚至当从单个线程使用这些集合时。 2.考虑到多线程的问题,现在一般采用ArrayList、LinkedList代替Vector，使用Deque代替Stack，使用 StringBuilder代替StringBuffer等等(特殊场景下,可能需要用到线程安全类,java.util.concurrent)

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