Is there ay inbuilt method to convert 2D array into CSV file?
e.g. Can anyone give me a hint to convert [1,2;3,4] into a file output.csv?

Not that I know of, but its easy enough to loop through your array printing the values (with commas inbetween) to a PrintStream based on the output file.

@stultuske: By inbuilt, i meant a class or a method in java.util or elsewhere that may do it...
@JamesCherill: Ok

have you tried saving your output file as "file.csv"? as long as your format is correct the file should open correctly in an application such as excel. Simply add ".csv" to your file name and youre good to go. I hope that answers your question.