Precautions to be taken while programming in java in ACM-ICPC?

What are the precautions or techniques that one should use while using JAVA as the programming language in programming contests like ACM-ICPC, Coz generally JAVA programs takes more time to run compared to C/C++…Also most of the time you get some runtime error, which sometimes makes JAVA a bit frustrating although it has got much more functionality compared to other languages…

I mean are there any constraints like the class should have a particular name like “Main” or something, and it should\shouldn’t be public and some particular methods for input and output must be used…???

I’m afraid that depends on location where you are in. Here, in Prague, we got example for some basic program. Additionally they told us that class name should be in lowercase. Typically there is some practice round before the live contest where you can try what environment accepts.