Java applications have a notoriously slow startup and a long warmup time. TheCRaC (Coordinated Restore at Checkpoint)project from OpenJDK can help improve these issues bycreating a checkpoint with an application's peak performanceand restoring an instance of the JVM to that point. To take full ...
userCityMapping.put(userName, "加利福尼亚"); System.out.println(userName + " 搬到了新城市 " + userCityMapping.get(userName) + ", New userCityMapping : " + userCityMapping); // The get() method returns `null` if the specified key was not found in the HashMap System.out.println("Li...
The difference withHashMaplies in what entails a structural modification.In access-ordered linked hash maps, merely calling thegetAPI results in a structural modification. Alongside this, are operations likeputandremove. 7. Conclusion In this article, we have explored JavaLinkedHashMapclass as one ...
}if(e !=null) {//existing mapping for key//此时e节点中记录的是hashMap中与我们要插入的节点相同的节点,在这里统一进行处理V oldValue =e.value;//记录旧的value值if(!onlyIfAbsent || oldValue ==null)//通过onlyIfAbsent与oldValue的值判断是否要进行覆盖e.value=value;//覆盖旧的值afterNodeAccess(...
/*** Associates the specified value with the specified key in this map. * If the map previously contained a mapping for the key, the old * value is replaced. * *@paramkey key with which the specified value is to be associated
=null){// existing mapping for key//不为空的话证明是修改操作，取出老值VoldValue=e.value;//...
= null) { // existing mapping for key V oldValue = e.value; if (!onlyIfAbsent || oldValue == null) e.value = value; afterNodeAccess(e); return oldValue; } } ++modCount; //如果元素个数大于临界值则扩容 if (++size > threshold) resize(); afte...
if(e.hash==hash&&//判断在循环节点过程中如果有键值相等就结束循环-此时e存的是((k=e.key)==key||(key!=null&&key.equals(k)))break;p=e;//此时p或许是新节点并且被当前链表尾节点指向了 或许是p的节点的key与新节点的key相等了}}if(e!=null){// existing mapping for keyVoldValue=e.value;/...
一、糟糕的面试面试官：小王，你说说HashMap的是线程安全的吗？小王：HashMap不安全，在多线程下，会出现线程安全问题。他兄弟HashTable线程是安全的，但是出于性能考虑，我们往往会选择ConcurrentHashMap。面试官：HashMap线程不安全的原因是什么？小王：这个...暂时忘记了面试官：为什么HashTable线程安全，为什么性能低...
equals(e); } public boolean remove(Object o) { return removeMapping(o) != null; } public int size() { return size; } public void clear() { HashMap.this.clear(); } } // java.io.Serializable的写入函数 // 将HashMap的“总的容量,实际容量,所有的Entry”都写入到输出流中 private void...