Posted in: Core Java
- Always use the simplest classes possible to get the Job Done.
- Never code your own frameworks unless the performance is lacking. Reuse code and frameworks.
- Use open source frameworks which are established and tested.
- Learn Collections and use them correctly. Use "lightweight" collections and avoid "heavyweight" collections where synchronization is not required.
- Use constants where possible by using static final in the variable declaration.
- Use Enum instead of integer constants. Enums are more flexible and are typesafe.
- Avoid casting and using instanceof
- Use synchronized methods instead of code blocks.
- Avoid synchronized calls within a synchronized method or code block.
- Do not recalculate constants inside a loop.
- "Fast Fail" - If a method fails, or throws an exception have it exit the loop quickly. Break loops early.
- Never use String or StringBuffer for parsing characters. Use a character array.
- Try to set the StringBuilder or StringBuffer to the size required, or maximum size required during initialization to prevent a performance penalty while resizing.
- Avoid using StringTokenizer if there is a performance requirement. Use a more specific (custom) tokenizer to split Strings. StringTokenizer is a generic utility that is synchronized internally.
- Avoid using generic object collections. Use generics with collections to avoid having to cast objects.
- Use a LinkedList over an ArrayList if there a large number of insertions and deletions.
- When given a choice use local interfaces and local method calls on EJBs.
Source: http://www.hostitwise.com/java/java-perfromance-tips.html