Unlike other programming languages like Java, when implementing an interface in GoLang, there is no syntax like below to explicit tell the relationship:type I interface {}type A struct implements I {}When looking at the code or running the code in GoLang, it might lead to a case one doesn't know whether a struct implements interface before trying to use it as some interface.According to GoLang spec, as long as a struct implements all functions of an interface, it is considered as having implemented that interface and can be used wherever that interface is expected.To check whether a struct imp...

HashMap is one of the most frequently used collection types in Java, it stores key-value pairs. Ideally it expects to use hash table which expects the data access time complexity to be O(1), however, due to hash conflicts, in reality, it uses linked list or red-black tree to store data which makes the worst case time complexity to be O(logn). Although collections are using data structures like arrays and linked lists, unlike arrays, they will dynamically resize when there is not enough space to store data  It involves copying data from old array to the new array which is considered a...

Singleton is frequently used in applications where resource may be expensive to create and no instance specific state needs to be maintained. For example, when creating database connection, a singleton may be needed. Today we will share the famous Singleton design pattern in Java.1. DefinitionSingleton design pattern is a design pattern that restricts the instantiation of a class to one object. It is one of the most well-known design patterns.2. ApplicationSingleton can be used in many occasions, for example, one database can have only one connection or connection coun...

HashMap in Java is frequently used to handle key/value pairs. But it is not a good candidate to be used in concurrent environment where ConcurrentHashMap should be used instead. If used in concurrent environment, it may cause lots of unexpected behavior even including make the program getting into an infinite loop situation.To understand how this can happen, let's first discuss how HaspMap works internally. In this post we will use implementation of HashMap before Java 8 as example, Java 8 provides a different version of HashMap implementation which is more efficient but more complicated as we...

Before going to understand unsafe package in GoLang, the first thing needs to talk about is the pointer in GoLang. If you have a background of C language, you must know what pointer means and its usage. With pointer, you are free to operate any data at memory level which means you have great power, but this means that you have great responsibility as well. That's why it might be considered unsafe in lots of cases.Take a look at a simple example of doubling an integer.package mainimport "fmt"func double(x int) { x += x}func main() { var a = 3 double(a) fmt.Println(a) // 3}The above ...

GoLang provides two major ways to loop through elements of array, slice and map. They are for and for range. Many people find that for range is very convenient when don't care about the index of the element. In this post, some tricks and tips would be talked about regarding for range.1. Loop and get pointer of each elementAssume there is a code snippet like below which is to get the pointer of each element in an array and create a new array with the corresponding pointer.arr := [2]int{1, 2}res := []*int{}for _, v := range arr { res = append(res, &v)}//expect: 1 2fmt.Println(*res[0],*res...

Have you ever wondered how many bytes a boolean value takes in Java? One byte, this might be the answer comes out of your mind right away. But is it? Let's dig in more.Per Oracle documentation on boolean value definition, there is below statement:boolean: The boolean data type has only two possible values: true and false. Use this data type for simple flags that track true/false conditions. This data type represents one bit of information, but its "size" isn't something that's precisely defined.From the description, it mentions that the size of the boolean value is not precisely defined. This ...

Artificial intelligence is having a say in how web designs are shaping up nowadays. Many within the industry have even gone on to say that AI is the future of web design and development. The impact of AI on web design and development can be felt by understanding how web design has evolved over the years. Traditionally, all websites were created using HTML. Then, with the advancement of technology, the code structure of websites began to change and became more sophisticated. Now, it has come to a point where designers and developers have started fantasizing about designing and developing websit...