# Package org.apache.tomcat.util.collections

package org.apache.tomcat.util.collections

- Related Packages
  Package
  Description
  org.apache.tomcat.util
- Classes
  Class
  Description
  CaseInsensitiveKeyMap<V>
  A Map implementation that uses case-insensitive (using `Locale.ENGLISH`) strings as keys.
  ConcurrentCache<K,V>
  A thread-safe cache that uses an eden space backed by a `ConcurrentHashMap` and a long-term space backed by a `WeakHashMap`.
  ConcurrentLruCache<T>
  A thread-safe LRU (Least Recently Used) cache with a configurable size limit.
  ManagedConcurrentWeakHashMap<K,V>
  Concurrent hash map that holds its keys via weak references.
  SynchronizedQueue<T>
  This is intended as a (mostly) GC-free alternative to `ConcurrentLinkedQueue` when the requirement is to create an unbounded queue with no requirement to shrink the queue.
  SynchronizedStack<T>
  This is intended as a (mostly) GC-free alternative to `Stack` when the requirement is to create a pool of re-usable objects with no requirement to shrink the pool.