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如何在JAVA中实现一个固定最大size的hashMap

利用LinkedHashMap的removeEldestEntry方法，重载此方法使得这个map可以增长到最大size，之后每插入一条新的记录就会删除一条最老的记录。

import java.util.LinkedHashMap;
import java.util.Map;public class MaxSizeHashMap<K, V> extends LinkedHashMap<K, V> {private final int maxSize;public MaxSizeHashMap(int maxSize) {this.maxSize = maxSize;}////Returns true if this map should remove its eldest entry. //This method is invoked by put and putAll after inserting a new entry into the map. //It provides the implementor with the opportunity to remove the eldest entry each time a new //one is added. This is useful if the map represents a cache: //    it allows the map to reduce memory consumption by deleting stale entries. //
    @Overrideprotected boolean removeEldestEntry(Map.Entry<K, V> eldest) {return size() > maxSize;}
}