a33b33C33的专栏

Q: In Java, under what circumstances would you use abstractclasses instead of interfaces? When you declare a method asabstract, can other nonabstract methods access it? In general,could you explain

遇到的问题：在/..../list/DList.javacompile已过。DList.java 属于 package list报错：javaDListException in thread "main" java.lang.NoClassDefFoundError: DList(wrong name: list/DList)at java.lang.ClassLoader.def

public class LFUCache {    HashMap hashtable = new HashMap();    int column;    PriorityQueue priorityQueue;        public LFUCache(int capacity) {        column = capacity;        KeyVa