What does java.lang.Thread.interrupt() do?

Thread.interrupt() sets the interrupted status/flag of the target thread. Then code running in that target thread MAY poll the interrupted status and handle it appropriately. Some methods that block such as Object.wait() may consume the interrupted status immediately and throw an appropriate exception (usually InterruptedException) Interruption in Java is not pre-emptive. Put another way both threads have to cooperate … Read more

How do I set the proxy to be used by the JVM

From the Java documentation (not the javadoc API): http://download.oracle.com/javase/6/docs/technotes/guides/net/proxies.html Set the JVM flags http.proxyHost and http.proxyPort when starting your JVM on the command line. This is usually done in a shell script (in Unix) or bat file (in Windows). Here’s the example with the Unix shell script: When using containers such as JBoss or WebLogic, my solution is to edit … Read more

Why nextLine() and not nextString() ?

Consider this: nextLine return everything until next endline (\n) in form of String. Would you not think that you will retrieve everything if it was called nextString? In that case you would be posting question “why nextString() stops at endline” tl;dr it’s because it searches for endline (\n) upd: on documenatation it refers to it … Read more

Good Java graph algorithm library?

If you were using JGraph, you should give a try to JGraphT which is designed for algorithms. One of its features is visualization using the JGraph library. It’s still developed, but pretty stable. I analyzed the complexity of JGraphT algorithms some time ago. Some of them aren’t the quickest, but if you’re going to implement them on … Read more

Only using @JsonIgnore during serialization, but not deserialization

Exactly how to do this depends on the version of Jackson that you’re using. This changed around version 1.9, before that, you could do this by adding @JsonIgnore to the getter. Which you’ve tried: Add @JsonIgnore on the getter method only Do this, and also add a specific @JsonProperty annotation for your JSON “password” field name to the setter method for the … Read more

How to convert int[] to Integer[] in Java?

I’m new to Java and very confused. I have a large dataset of length 4 int[] and I want to count the number of times that each particular combination of 4 integers occurs. This is very similar to counting word frequencies in a document. I want to create a Map<int[], double> that maps each int[] to a running count … Read more

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