Singleton: i prefer thread-safe implementations and generally eschew singletons (unless extreme political pressure dictates otherwise) https://www.geeksforgeeks.org/singleton-design-pattern/ [https://www.geeksforgeeks.org/wp-content/uploads/gfg_200X200.png]<https://www.geeksforgeeks.org/singleton-design-pattern/> Singleton Design Pattern | Implementation - GeeksforGeeks<https://www.geeksforgeeks.org/singleton-design-pattern/> The singleton pattern is one of the simplest design patterns. Sometimes we need to have only one instance of our class for example a single DB connection shared by multiple objects as creating a separate DB connection for every object may be costly. Similarly, there can be a single configuration ... www.geeksforgeeks.org
Design Patterns: have a look at this discussion from stackoverflow on Visitor Pattern vs Command Pattern for lambda expresssions https://stackoverflow.com/questions/2186931/java-pass-method-as-parameter [https://cdn.sstatic.net/Sites/stackoverflow/img/apple-touch-i...@2.png?v=73d79a89bded]<https://stackoverflow.com/questions/2186931/java-pass-method-as-parameter> interface - Java Pass Method as Parameter - Stack Overflow<https://stackoverflow.com/questions/2186931/java-pass-method-as-parameter> In Java 8, you can now pass a method more easily using Lambda Expressions and Method References. First, some background: a functional interface is an interface that has one and only one abstract method, although it can contain any number of default methods (new in Java 8) and static methods. A lambda expression can quickly implement the abstract method, without all the unnecessary syntax ... stackoverflow.com although this discussion is more specific on when to implement Visitor Pattern vs when to use Command Pattern https://stackoverflow.com/questions/2857880/command-pattern-vs-visitor-pattern [https://cdn.sstatic.net/Sites/stackoverflow/img/apple-touch-i...@2.png?v=73d79a89bded]<https://stackoverflow.com/questions/2857880/command-pattern-vs-visitor-pattern> Command Pattern vs. Visitor Pattern - Stack Overflow<https://stackoverflow.com/questions/2857880/command-pattern-vs-visitor-pattern> Each pattern has it's own pros, cons and use cases. You can use Command pattern to . Decouple the invoker & receiver of command . Implement callback mechanism. Implement undo and redo functionality. Maintain a history of commands. Use Visitor pattern in below scenarios:. Similar operations have to be performed on objects of different types grouped in a structure ; You need to execute many ... stackoverflow.com ?am interested to know which topic prompts your question? /br/ Martin ________________________________ From: Lukasz Lenart <lukaszlen...@apache.org> Sent: Thursday, December 12, 2019 1:56 AM To: Struts Users Mailing List <user@struts.apache.org> Subject: Re: Java Singleton , Framework Design Patterns czw., 12 gru 2019 o 06:13 Zahid Rahman <zahidr1...@gmail.com> napisał(a): > So my point is I have not been able to find accurate information , if some > one could furnish me a Java language specification or recommend a book > which accurately describes these I would be grateful. Start with Gang of Four http://www.blackwasp.co.uk/gofpatterns.aspx Regards -- Łukasz + 48 606 323 122 http://www.lenart.org.pl/ --------------------------------------------------------------------- To unsubscribe, e-mail: user-unsubscr...@struts.apache.org For additional commands, e-mail: user-h...@struts.apache.org
