In Java an array has a fixed size (after initialisation), meaning that you can’t add or remove items from an array. The above snippet mean that the array of integers has a length of 10. It’s not possible add an eleventh integer, without re-assign the reference to a new array, like the following: In Java … Read more
UPDATEYou can use Apache Commons Codec (version 1.7+) to do this job for you. DigestUtils.sha1Hex(stringToConvertToSHexRepresentation) Thanks to @Jon Onstott for this suggestion. Old AnswerConvert your Byte Array to Hex String. Real’s How To tells you how. and (copied from Real’s How To) BTW, you may get more compact representation using Base64. Apache Commons Codec API 1.4, has this nice utility … Read more
JSP (JavaServer Pages) JSP is a Java view technology running on the server machine which allows you to write template text in client side languages (like HTML, CSS, JavaScript, ect.). JSP supports taglibs, which are backed by pieces of Java code that let you control the page flow or output dynamically. A well-known taglib is JSTL. JSP also supports Expression … Read more
In Java System.out.println() will print to the standard out of the system you are using. On the other hand, System.err.println() will print to the standard error. If you are using a simple Java console application, both outputs will be the same (the command line or console) but you can reconfigure the streams so that for example, System.out still prints to the … Read more
Edit 2; worth putting on top: I think it is worth mentioning that this is actually downloading all data at this snapshot just to check whether any data exists. You should be mindful here. If the reference is huge (e.g. actually the root reference and not a specific child/property) then you should either find a deeper node you … Read more
Consider Column lengths differ per row. If you’re backing some data by a fixed size 2D array, then provide getters to the fixed values in a wrapper class.
Error is self explainatory: javax.mail.MessagingException: Could not connect to SMTP host: localhost, port: 25; You have no SMTP server on localhost, but you configure it there : So you must: either configure a local SMTP server as a relay on your local system (Postfix or sendmail are two well knows servers) of configure a dummy server that simply … Read more
If you want to convert an Instant to a Date: And then you can use SimpleDateFormat for the formatting part of your question:
There is charts4j which is a charts and graphs API. It enables developers to programmatically create the charts available in the Google Chart API through a straightforward and intuitive Java API. Disclaimer: I wrote charts4j. We will be doing another major release in the next few weeks.