java Performance Test clues

Hi ,
As i read in one article about java performance test .Here are some clues which i got from article.
When ever u are doing performance testing for java code make sure following points
1) As per Performace test use what are exisitng poplular java performance tools .
2) when ever u are doing performance testing on LOOPS like While,for,Iterator you should nt get variant results. If it is

2.1 Repeat the performance tests for particular code ,and make sure results are same.
2.2 Before doing testing make sure that all applications are closed like word etc ,because if your jvm using any bit of application results will vary.
2.3 Check your memory available in CPU .
2.4 Check the threads which are dependent on other threads.

3) At last check all the methods or application code which is contacting outside application .

These are some clues i found , you please refer certain performance tools available in market .