I have a MongoCollection<Document> in which I assign a collection. I’m trying to find a user by his id. with that I’m getting an error java.lang.ClassCastException: com.mongodb.FindIterableImpl cannot be cast to org.bson.Document When I try I’m getting an error The method find(Bson, Cl…
Tag: java
Overflow occurs with multiplication
The above code creates overflow and doesn’t print the correct result. The above 2 lines print the correct result. My questions are- Does it matter to the compiler which I use, m2 or m3? How does java starts multiplying? Left to right or right to left? Does 24*60 gets computed first or 1000*1000? Answer …
How to de/serialize an immutable object without default constructor using ObjectMapper?
I want to serialize and deserialize an immutable object using com.fasterxml.jackson.databind.ObjectMapper. The immutable class looks like this (just 3 internal attributes, getters and constructors): However when I run this unit test: I get this exception: This exception asks me to create a default constructor…
Can anyone tell me how to test my Camel Route if I have a choice operation?
I have a Camel route that has implemented a Content based Routing EIP(Choice operation). I need to test it. I’m new to Camel. So, I’m unsure how to do it. Can anyone tell me how to test this operation. I have mentioned a sample code below that has to be tested. Answer You can simply “advice&…
Bootstrapping Guice injector
I have a scenario where I will need some objects injecting at the start like logging, but then other objects injected on demand. What I don’t know is if in my console application, do I just call: in my Main function and then when I need another object, the type that I need on demand, do I use a Provider
CompletableFuture from Callable?
Today I experimented with the “new” CompletableFuture from Java 8 and found myself confused when I didn’t find a runAsync(Callable) method. I can do it myself like shown below, but why is this (to me very obvious and useful utility method) missing? Am I missing something? Answer You are supp…
Spring Rest Controller Return Specific Fields
I’ve been going through my head the best way to design a JSON API using Spring MVC. As we all know IO is expensive, and thus I don’t want to make the client make several API calls to get what they need. However at the same time I don’t necessarily want to return the kitchen sink. As an examp…
Error code -7 when trying to install release APK
I’ve taken all appropriate steps to create the release APK. (Demonstration of steps required) My device (Nexus 7 2012) is set to allow installs from unknown sources. I emailed the APK (app-release.apk) to myself and attempted to open it from GMail, as this should work. EDIT: I apologize, I also should h…
How configure connection existence check in C3P0?
I am using the below code to get Connection. I have used the c3p0 library for connection pooling. Now my question is, this code is not checking whether the connection is existing or not. Most likely this will get hit by the famous connection closed error after 8 hours. While I was using C3P0 with hibernate, t…
Jenkins CLI connection refused
When executing I’m getting connection refused for some reason. Jenkins version is 1580.3, user has the permissions on Jenkins server, cli jar is up-to-date and ssh public key is configured properly. Any idea what might be causing this? Here’s the stack trace if it will help: Answer If the connecti…