I’m using tomcat embedded and when I try to star the server following error get occurred. I’m using tomcat 8.0.20 and jdk8 Why I’m getting this? And what can I do to fix thi? Answer I was able to fix this issue by disabling the default TomcatURLStreamHandlerFactory before starting the sever …
Tag: java-8
Logging from default interface methods
Salut to all Java gurus! Since Java8 we can have default implementations in interfaces (yay!). However problem arises when you want to log from default method. I have a feeling that it is not wise to call .getLogger() every time I want to log something in a default method. Yes, one can define static variable …
Perform operation on n random distinct elements from Collection using Streams API
I’m attempting to retrieve n unique random elements for further processing from a Collection using the Streams API in Java 8, however, without much or any luck. More precisely I’d want something like this: I want to do it as efficiently as possible. Can this be done? edit: My second attempt —…
When and why would you use Java’s Supplier and Consumer interfaces?
As a non-Java programmer learning Java, I am reading about Supplier and Consumer interfaces at the moment. And I can’t wrap my head around their usage and meaning. When and why you would use these interfaces? Can someone give me a simple layperson example of this? I’m finding the Doc examples not …
JDK8 – Error “class file for javax.interceptor.InterceptorBinding not found” when trying to generate javadoc using Maven javadoc plugin
I am using JDK8 (tried it on my Eclipse workspace with Win x64 u25 JDK + on Linux launched by Jenkins – jdk-8u20-linux-x64, same problem for both). I have multi-module Maven project (I am launching Maven goal “javadoc:aggregate” from a main module with packaging type “pom”). Pom …
Java access bean methods with LambdaMetafactory
my question is strongly related to Explicit use of LambdaMetafactory in that thread, some very good examples are provided to use the LambdaMetafactory to access a static method of a class; however, I wonder what is the equivalent code to access a non static field of an existing bean instance. It seems really …
Unit testing a class with a Java 8 Clock
Java 8 introduced java.time.Clock which can be used as an argument to many other java.time objects, allowing you to inject a real or fake clock into them. For example, I know you can create a Clock.fixed() and then call Instant.now(clock) and it will return the fixed Instant you provided. This sounds perfect …
What’s the difference between map() and flatMap() methods in Java 8?
In Java 8, what’s the difference between Stream.map() and Stream.flatMap() methods? Answer Both map and flatMap can be applied to a Stream<T> and they both return a Stream<R>. The difference is that the map operation produces one output value for each input value, whereas the flatMap operati…
How to generate random array of ints using Stream API Java 8?
I am trying to generate random array of integers using new Stream API in Java 8. But I haven’t understood this API clearly yet. So I need help. Here is my code. But this code returns array of objects. What is wrong with it? Answer If you want primitive int values, do not call IntStream::boxed as that pr…
“Undefined reference: .. ConcurrentHashMap.keySet()” when building in Java 8
i have a project, and i am build this project with jdk 6,7,8 and my target is 1.6 when i build jdk 8 i get this error: Undefined reference: java.util.concurrent.ConcurrentHashMap.KeySetView java.util.concurrent.ConcurrentHashMap.keySet() since i have this code in that line: how can avoid error, i made some se…