1. Use StringBuilder append method to concatenate strings instead of '+' operator. PSA program and see the result.
2. Use static final private methods wherever applicable. These methods are resolved faster than others .
3. Use String.intern method to improve performance.
4. Initialize values to defaults where ever required instead of setting it explicitly.
5. Use Long.valueof method instead of creating new Long object.
6. Catch specific exception instead of catching generic exception.
7. Avoid try/catch blocks in for loop.
8. Call equals method on static final string on dynamic string(CONSTANT.equals(dynamicString)).
9. Create collection with minimal size
