HashMap返回未找到密钥的默认值？ [英] HashMap to return default value for non-found keys?

问题描述

可以有一个 HashMap 返回在集合中找不到的所有键的默认值

Is it possible to have a HashMap return a default value for all keys that are not found in the set?

推荐答案

没有地图实现完全是这样做的，但是通过扩展HashMap来实现自己是不重要的：

There's no Map implementation that does this exactly but it would be trivial to implement your own by extending HashMap:

public class DefaultHashMap<K,V> extends HashMap<K,V> {
  protected V defaultValue;
  public DefaultHashMap(V defaultValue) {
    this.defaultValue = defaultValue;
  }
  @Override
  public V get(Object k) {
    return containsKey(k) ? super.get(k) : defaultValue;
  }
}

这篇关于HashMap返回未找到密钥的默认值？的文章就介绍到这了，希望我们推荐的答案对大家有所帮助，也希望大家多多支持IT屋！