Coding: Be strong with the basics. Tutorials must be gone through, exercises must be done and the lessons must be well read. While creating a code, make sure you understand each and every line. Keep utilities and configuration snippets as they are all very vital.
OOPS – Build Strong Foundation: Having a strong understanding in OOP (Object Orientation Program) is a must. Without having much knowledge on OOPS nobody can understand the beauty of JAVA programming.
Follow Technology Trends and Practice Hard: Always be on the lookout for new framework and always stay updated. Creating a simple client server TCP service and using them will help a lot. Understanding the source codes of various successful and popular frame-works is a must and it can only be achieved with a lot of practices.
Keeping the problems solved: All software are designed to solve user problems and a wide range of other problems. A good Java Developer understands the class loading process and how it usually works. Understanding the garbage collection and minimizing it is a must. A good java developer must also know when to use the design pattern.
Mastering Core APIs: Many people may be strong on theoretical knowledge, but having a strong knowledge on APIs is a must. When it is web application development having a strong and fixed ideas on JSPs is a must.
Conversation Participation: Working on new technology is a must as it is the best thing going forward. Subscribe to technology forums, because whatever issue you might face, someone might have faced it earlier and may have come up with a solution. Following good blogs and commenting or responding to it also gives a good value.
Ability to deal with people: A java developer not only needs to be strong in technological aspect, but also in the personality traits as well. The person must be able to deal with customers, managers and even developers.
Leadership Skills: Being a good leader is also vital, and if you want to be a leader, you must be a good listener, mentor, must share your knowledge and also must handle situations and accept mistakes.