We all know that in order to invoke Object.wait(), this call must be placed in synchronized block, otherwise an IllegalMonitorStateException is thrown. But what’s the reason for making this restriction? I know that wait() releases the monitor, but why do we need to explicitly acquire the monitor by maki…
how to find 2 to the power of n . n ranges from 0 to 200
Assume my system as 32 bit machine. Considering this if I use long int for n>63 I will get my value as 0. How to solve it?
Using Regular Expressions
I am having problems trying to use the regular expression that I used in JavaScript. On a web page, you may have: Renewal Date: 03 May 2010
I just want to be able to …
What does the Java assert keyword do, and when should it be used?
What are some real life examples to understand the key role of assertions? Answer Assertions (by way of the assert keyword) were added in Java 1.4. They are used to verify the correctness of an invariant in the code. They should never be triggered in production code, and are indicative of a bug or misuse of a…
How to cast a list of inheriting objects to a collection of objects in Java?
I’ve a collection type: And I’ve a list in my object: Where B is extending A But I can’t do the following: I can’t understand why since Collection is implemented by List. Answer Let’s assume for a moment you could do what you describe: The method call collecA.add(new A()) appears…
how to convert minutes to days,hours,minutes
how to convert minutes into days hours and minutes in java ( we have a week here , 7 days ) I tried this but it dont work thanks Answer A shorter way. (Assumes time >= 0)
What is the “owning side” in an ORM mapping?
What exactly does the owning side mean? What is an explanation with some mapping examples (one to many, one to one, many to one)? The following text is an excerpt from the description of @OneToOne in Java EE 6 documentation. You can see the concept owning side in it. Defines a single-valued association to ano…
Want to store Object in MySQL database
I have a variable in java which return type is Object(java.lang.Object). I want to store this variable value in MySQL database without casting in any other primitive data type. Is there any data type available in MySQL related to Object? Answer You can use a BLOB to store the raw data, but otherwise no, MySQL…
Alternatives to JSP for Spring MVC view layer [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 last year. The community revie…
log4j vs. System.out.println – logger advantages?
I’m using log4j for the first time in a project. A fellow programmer told me that using System.out.println is considered a bad style and that log4j is something like standard for logging matters nowadays. We do lots of JUnit testing – System.out stuff turns out to be harder to test. Therefore I be…