Skip to content

Tag: java

What is the Scanner class used for in Java? [closed]

Closed. This question does not meet Stack Overflow guidelines. It is not currently accepting answers. We don’t allow questions seeking recommendations for books, tools, software libraries, and more. You can edit the question so it can be answered with facts and citations. Closed 1 year ago. Improve this quest…

How to format decimals in a currency format?

Is there a way to format a decimal as following: If it is a round number, omit the decimal part. Otherwise format with two decimal places. Answer I doubt it. The problem is that 100 is never 100 if it’s a float, it’s normally 99.9999999999 or 100.0000001 or something like that. If you do want to f…

Java: for loop, incompatible types

I’m trying to run this for loop; However every time I try to compile I get an error stating ‘incompatible types – found int but expected boolean’ I can’t work out what I’m doing wrong! Answer the second statement: grid[0].length is an integer. The second statement in a for …

Excluding classes in Maven Checkstyle plugin reports

I have a Maven 2 project and I want to configure my Checkstyle report plugin so that only some of my classes are analysed. I have found the maven.checkstyle.excludes property, but despite passing this as a command line parameter (using -D=maven.checkstyle.excludes=…) I can’t get it to work. I can&…

Should Enterprise Java entities be dumb?

In our legacy Java EE application, there are loads of value object (VO) classes which typically contain only getters and setters, maybe equals() and hashCode(). These are (typically) the entities to be saved in persistence storage. (For the record, our app has no EJBs – although that might change in the…

java thread reuse

I have always read that creating threads is expensive. I also know that you cannot rerun a thread. I see in the doc of Executors class: Creates a thread pool that creates new threads as needed, but will reuse previously constructed threads when they are available. Mind the word ‘reuse’. How do thr…

Changing font-size at runtime in a Swing application

A lot of web sites these days have an option to let the user increase or decrease the size of the font that appears on the site. I’d like to add similar functionality to my Java Swing app, with an option to change the font to either a larger size or revert to standard size. The user would be able

Why doesn’t String’s hashCode() cache 0?

I noticed in the Java 6 source code for String that hashCode only caches values other than 0. The difference in performance is exhibited by the following snippet: Running this in ideone.com gives the following output: So my questions are: Why doesn’t String’s hashCode() cache 0? What is the probab…

Window resize event?

I’m writing a simple painting program using Java, and I want some method to be called whenever the JFrame component is resized. However I can’t find any method like windowResizedListener or an event like windowResizedEvent. What can I do?! Answer Implement a ComponentAdapter with componentResized(…