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A use case I have a form which has requirements as follow: - There are some mandatory fields. - Validation is triggered when changing value on each field. - A button "Next" is enable only when all fields are entered. It turns to disabled if any field is empty. My first approach I defined a variable "isDisableNext" at a backend bean "Controller" for dynamically disabling/enabling the "Next" button by performing event "onValueChange", but, it had a problem: <h:form id="personForm"> <p:outputLabel value="First Name" for="firstName"/> <p:inputText id="firstName" value="#{person.firstName}" required="true"> <p:ajax event="change" listener="#{controller.onValueChange}" update="nextButton"/> </p:inputText> <p:outputLabel value="Last Name" for="lastName"/> <p:i

The following is a series of posts about "functional programming in Java" which is the result of my understanding by reading the book " Java 8 in Action: Lambdas, Streams, and Functional-style Programming, by Alan Mycroft and Mario Fusco ". 1. Why functional programming? 2. Functional programming in Java 8 3. Java 8 - Using Functions as Values 4. Java 8 - Persistent data structure In general, the phrase "functional-style programming" means the behavior of functions should be like that of mathematical-style functions - no side effects. In programmers' point of views, functions may be used like other values: passed as arguments, returned as result, and stored in data structures . That means we can use the :: operator to create a method reference, and lambda expressions to directly express function values . For example: //method reference Function<String, Integer> strToInt = Integer::parseInt; //lambda expression Comparator<Integer&g

In my previous post , we discussed about why we should consider to use functional programming. Now, let's delve into what functional programming in Java is. What is pure functional programming? Shortly,  f unctional programming is programming using functions. A function corresponds to a mathematical function such as log, sin. Basically, it takes zero or more arguments, give one or more result, and has no side effects. We can't completely program in pure functional style in Java Why?  For example, calling Scanner.nextLine twice typically gives different result. So, it's just called "functional-style programming". How is that? - There is no mutating structures visible to callers. That means your side effect may not be visible to a program, but it's visible to the programmer in terms of slower execution. - A function or method shouldn't throw any exceptions (follows the concept "pass arguments, return result"). We can use types like Opti

Run Java run! ;) References [1].  http://openjdk.java.net/projects/jdk9/ [2].  https://blogs.oracle.com/theaquarium/java-ee-8-is-final-and-glassfish-50-is-released

Did you know how new features were added into Java 7? The following are functionalities that can be considered. Source: [1] Project Coin  is all about the changes in the range from syntactic sugar to new language feature. This is what we're talking about today. Since Java 7 is the first version developed in an open source manner, there is an amount of actions that must be performed for any changes as follows: Update the Java Language Specification (JSL) Implement a prototype in the source compiler Add library support essential for the change Write tests and examples Update document Etc, ... Project Coin has submitted a lot of proposals (almost 70) but only some of them are chosen to Java 7. Why? Briefly, Java is a rich static type system and it has a lot of possible interaction points between different bits of it. Making changes to this type system is prone to creating unexpected surprises. Wow! It is tough, right? Let's take a look what features Project Coi

Fansipan is a mountain in Vietnam, the highest in Indochina, at 3,143 metres . It is located in the Lào Cai Province of the Northwest region of Vietnam, 9 km southwest of Sa Pa Township in the Hoang Lien Son mountain range. Wikipedia Currently you can get the peak by cable car; however, I loved to explore it by climbing. Here are what I have learned from this exciting journey. 💪 Do not procrastinate I have had no experience of climbing a high mountain before. Then, I've sought advice from my friends, but they suggested that I should not make it at that time due to bad weather and lack of experience. I know it never come true unless I just make my decision. Can't wait! Prepare for your journey You firstly need getting to know about the journey, schedule, transportation, etc. Recommended sources: YouTube videos, blog posts and tour companies websites. Tips - Quality hiking shoes helps a lot - Bring your stuffs as light as possible. Important stuffs:

#RandomlyPickedByMe What is the difference between Javascript and Java? Difference between StringBuilder and StringBuffer? Why do I get "SomeType@a3fde" when I print my code? Why is String immutable? Why "equals" method when we have "==" operator? Is List<Dog> a subclass of List<Animal>? Why shouldn't we use raw type? Is Java “pass-by-reference” or “pass-by-value”? What's the advantage of a Java enum versus a class with public static final fields? Why "double x = 0.1 + 0.2" and result of print(x) is 0.30000000000000004? 1. What is the difference between Javascript and Java? Holy crap! (Vietnamese: Thế quái nào lại có câu hỏi ngớ ngẩn vậy chứ?) "Java and Javascript are similar like Car and Carpet are similar." - Greg Hewgill (on StackOverflow) 2. Difference between StringBuilder and StringBuffer String is immutable. StringBuilder and StringBuffer are mutable. StringBuffer is thread-safe. String