A frequently asked question in a Java interview is: How to implement a Java HashMap? Java job seekers must fully grok this important concept if they want to ace the interview. The HashMap tutorial ...

Java中，数组是一种常用的数据结构，它允许我们在内存中存储多个相同类型的元素。然而，在一些情况下，我们需要对数组中的元素进行去重操作，以避免重复计算或数据混乱的问题。本文将介绍几种简单高效的方法来实现Java数组去重，并提供相关的代码示例。

There are various instances of this issue that we get such as JAVAC’, JRE, ‘MVN’, JAR’ is not recognized as an internal or external command, operable program or batch file, ‘Java’ is not recognized as ...

I found a bug using mockito on JDK 17 (Temurin) and Linux Ubuntu 22.10. If we spy the HashSet and after add some value, it should throw NullPointerException. On JDK 11 it works fine.

While the Hashtable was part of the initial Java release over two decades ago, the HashMap is the correct key-value store to use today. One key HashMap vs. Hashtable difference is the fact that the ...

之所以把HashSet和HashMap放在一起讲解，是因为二者在Java里有着相同的实现，前者仅仅是对后者做了一层包装，也就是说HashSet*里面有一个*HashMap（适配器模式）。因此本文将重点分析HashMap。 HashMap实现了Map接口，即允许放入key为null的元素，也允许插入value为null的 ...

ArrayList就是传说中的动态数组，用MSDN中的说法，就是Array的复杂版本。ArrayList 是以数组实现的，遍历时很快，但是插入、删除时都需要移动后面的元素，效率略差些。它提供了如下一些好处： boolean add（Object obj） 将指定元素obj追加到集合的末尾 Object get（int ...