Software Development
Any and all content related to Java.
Here’s an example of how to customize the javax.validation.Validator instance in Spring 5. Validator is the Java API for bean validation that was introduced in the JSR-303 specification. Hibernate Validator is bundled with Spring Boot 2, and is the de facto reference implementation for bean validation. Why would you need to do something like this? Read More …
Spring Boot has had support for enabling CORS in REST controllers since version 1.3. The @CrossOrigin annotation is straightforward to apply at the method or type level to enable cross origin requests: Testing with cURL cURL is an obvious choice for testing CORS with Spring Boot RESTful API endpoints. results in the following output: Changing Read More …
This was a fun problem: create a program to rank a 5-card poker hand, e.g. “Royal Flush”. Given two poker hands, be able to determine which one is the winner. My first implementation took about an hour, but failed to include code for tie-breaking hands with equal rankings. It wasn’t difficult to modify my original Read More …
The person who told me about this problem ran into a bug in a web service for sending a collection of emails. If the collection contained more than one email addressed to the same recipient, an error would occur. He needed to write an algorithm which processes a collection such that it organizes emails into Read More …
This is an interesting maximization problem that can be solved efficiently, in O(n) time, using dynamic programming. You’re given a list of houses, each with a money value assigned to it. The problem is to choose houses from the list so as to maximize the total money from them, but no two houses chosen can Read More …
It can be challenging to get Java RMI communication working right between components on multihomed hosts. To see why, it’s important to understand how RMI determines the server hostname, which ultimately ends up being passed around in RMI stubs. If a client uses an RMI stub to make a remote method call and can’t connect Read More …
Today I was confronted with the problem of obtaining a list of all namespace attributes for a given XML document. I found that it’s possible to achieve this quickly using the XPath expression //namespace::*, which leverages the namespace axis defined in the XPath 1.0 specification. I’m using Xalan bundled with Sun JDK 1.6, and so Read More …
It’s more difficult to download Sun’s JDK 1.5 now (version 1.5.0_22 to be precise as I write this) that the company has officially announced its end-of-life. Downloading it by following the normal path on Sun’s website will land you at a registration form explaining that “Sun offers Java SE for Business, a service offering that provides Read More …
XPath is usually the perfect language, providing a simple and elegant way to compute values from the content of an XML document. For example, say that you want to count the number of elements. The XPath 1.0 query for this is about as concise as it gets: 1 XPathFactory xPathFactory = XPathFactory.newInstance(); 2 XPath xPath Read More …
If you’re like me it can be useful to convert a DOM in Java into a formatted XML string. Pretty-printing a DOM Element can augment the information gleaned from your debugger when tracking down a bug, for example. I’ll show you three ways to pretty-print XML from a Java DOM below. All of them format Read More …