Usually, this error is thrown when the [Java Virtual Machine](http://net-informations.com/java/intro/jvm.htm) cannot allocate an object because it is out of memory, and no more memory could be made available by the garbage collector.
Therefore you pretty much have two options:
* Increase the default memory your program is allowed to use using the -Xmx option (for instance for 1024 MB: -Xmx1024m)
* Modify your program so that it needs less memory, using less big data structures and getting rid of objects that are not any more used at some point in your program
Increasing the heap size is a bad solution, 100% temporary. It will crash again in somewhere else. To avoid these issues, write high performance code.
* Use local variables wherever possible.
* Make sure you select the correct object (EX: Selection between String, StringBuffer and StringBuilder)
* Use a good code system for your program(EX: Using static variables VS non static variables)
* Other stuff which could work on your code.
* Try to move with Multy Threading