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.
//
@Override
protected boolean removeEldestEntry(Map.Entry<K, V> eldest) {
return size() > maxSize;
}
}