How to use Java varargs
The three dots in a method parameter type is a feature called Java varargs. It was introduced in Java 5 and is formally known as variable arity methods or variadic functions.
Java
Ways to program your drone to do awesome stuff
Drones, quadcopters, RS helicopters and other remote controlled crafts are hot topic these days. We programmers are more interested in how to program them to do something cool. Indeed, it’s become more and more easy.
Blaze advisor error: this function should be called while holding treeLock
Problem
As a Blaze Advisor rules programmer, I often get errors like this. They are almost always Java related. Last time I struggled with “JVM not found” while installing the Blaze Advisor IDE.
WebSphere Application Server problems when changing to Java7
I needed to reinstall my WebSphere Application Server several times and as a result the server wouldn’t start at all with the following error:
Java quiz: Object Orientation
1. What is encapsulation:
a) the ability to make changes in your implementation without breaking the code of others
b) keep instance variables accessible foe everyone
c) create getters and setters rather then give direct access to instance variables
Java quiz: Declarations and Access
1. What is a Java program?
a) A collection of classes
b) A collection of objects talking to other objects by invoking each others methods
c) A template that describes the kinds of state and behavior that objects of its type support
2. Java components are:
a) types
b) classes
c) variables
d) objects
e) instances
f) methods
Blaze Advisor: No matching JVM was found
Installing Blaze Advisor is not always easy. The problem often is that Blaze Advisor installation can’t find java on your pc. Here is how I do it:
Inheritance Java equality check
We’ve earlier written a post about Recipe for a high-quality “equals” method. This is harder to get right in the case of inheritance.
Hibernate: how to enable show sql
To see the SQL that your application sends to the database during the execution, insert the following property in your XML property file:
XPath examples – Hibernate java mapping
Those who use hibernate for database access know that you need to provide an information that this object is a hibernate object. To do so you typically need to annotate your object with @Entity. It’s not a problem although if we speak about some large system. In large systems we have typically a number of instances of the same object that represent the same table in different contexts and packages. And here we need this: to give each object unique name.
Example:
