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Tag: java
Do Java arrays have a maximum size?
Is there a limit to the number of elements a Java array can contain? If so, what is it?
GPS Time Representation library
I am looking for a Java library that handles conversion to/from GPS Time. GPS Time has an epoch of 6 January 1980, and does not have leap seconds, so it differs from the more standard time representations. Here is the relevant description from wikipedia: While most clocks are synchronized to Coordinated Unive…
In Java, is there a way to write a string literal without having to escape quotes?
Say you have a String literal with a lot of quotation marks inside it. You could escape them all, but it’s a pain, and difficult to read. In some languages, you can just do this: In Java, however, ” is used for chars, so you can’t use it for Strings this way. Some languages have syntax to wo…
When to use Spring Integration vs. Camel?
As a seasoned Spring user I was assuming that Spring Integration would make the most sense in a recent project requiring some (JMS) messaging capabilities (more details). After some days working with Spring Integration it still feels like a lot of configuration overhead given the amount of channels you have t…
Shortcut for adding to List in a HashMap
I often have a need to take a list of objects and group them into a Map based on a value contained in the object. Eg. take a list of Users and group by Country. My code for this usually looks like: However I can’t help thinking that this is awkward and some guru has a better approach. The closest
Very Simple Regex Question
I have a very simple regex question. Suppose I have 2 conditions: url =http://www.abc.com/cde/def url =https://www.abc.com/sadfl/dsaf How can I extract the baseUrl using regex? Sample output: http://www.abc.com https://www.abc.com Answer Like this: However, you should use the URI class instead, like this:
How can I create an empty dummy HttpResponse
I am using org.apache.http.HttpResponse I want to create an empty dummy resposne, I am going to use this to return when errors occur instead of passing back null. I tried to create one and it has lost of weird params. Can someone tell me how to create one. Answer Just implement HttpResponse with no-op methods…
Difference between FetchType LAZY and EAGER in Java Persistence API?
What is the difference between FetchType.LAZY and FetchType.EAGER in Java Persistence API? Answer Sometimes you have two entities and there’s a relationship between them. For example, you might have an entity called University and another entity called Student and a University might have many Students: …
What are the differences between ArrayList and Vector?
What are the differences between the two data structures ArrayList and Vector, and where should you use each of them? Answer Differences Vectors are synchronized, ArrayLists are not. Data Growth Methods Use ArrayLists if there is no specific requirement to use Vectors. Synchronization If multiple threads acce…