Exception in thread "main" java.lang.OutOfMemoryError: Java heap space

This error message indicates that the Java program has run out of memory allocated to it by the operating system. This can happen when the program is trying to allocate more memory than the maximum allowed by the system or when it is trying to store too much data in memory.

To fix this issue, you can try increasing the heap size of the Java Virtual Machine (JVM) by adding the following command line arguments when running the program:

-Xms<size> -Xmx<size>

where <size> is the desired amount of memory in megabytes (e.g. -Xms512m -Xmx1024m).

You can also try optimizing the code to use less memory by reducing the amount of data stored in memory at any given time or by using more efficient data structures. Additionally, you can try running the program on a system with more memory available.