Essential Skills and Knowledge for Becoming a Senior Java Developer

Everyone dreams of becoming a top programmer; to become a senior Java developer you need a broad set of knowledge.

Core Java : object‑oriented programming concepts (encapsulation, inheritance, polymorphism, interfaces), string handling, common packages such as java.lang and java.util, and exception handling.

Advanced Java : I/O streams, multithreading, network programming, and Swing (the latter optional unless required by a project).

Frontend basics : HTML + CSS for web development, JavaScript, jQuery, and an understanding of browser compatibility and CSS hacks.

Web technologies : Proficiency with JSP and Servlets, MVC design pattern and related frameworks such as Struts, the SSH framework, and session & cookie management.

Tools & environments : Mastery of at least one Java IDE (Eclipse, MyEclipse, JBuilder, JCreator), XML processing (JDOM, w3c.dom, SAX), build tools (Ant or Maven), version‑control systems (CVS, VSS, SVN), Linux command line and shell scripting, and basic Windows batch scripting.

Databases : In‑depth knowledge of Oracle (views, indexes, stored procedures, triggers, cursors, packages, common functions) and familiarity with at least one other DBMS (MySQL, SQL Server, Access). Understanding of database principles, transaction theory, locking mechanisms, complex queries, performance tuning, and JDBC with connection pools.

Design patterns & advanced concepts : Familiarity with common Java design patterns (Factory, Singleton), reflection mechanisms, JVM internals (memory management, garbage collection, heap/stack), testing frameworks (JUnit, Mockito), logging (log4j), UUID generation, regular expressions, and JNDI/JMS.

Additional languages & frameworks : Basic knowledge of C, C++, .NET, scripting languages such as Python or Ruby, PHP/ASP, and at least one JavaScript framework (e.g., Prototype). Awareness of Flex (optional), GWT, and Closure.

Other essential topics : HTTP protocol fundamentals (request/response, status codes, HTTPS), Ajax and reverse Ajax, Linux deployment and shell scripting, Windows batch files, HTML5 basics, JavaMail, file I/O (text, Excel via JXL), JVM profiling, UML modeling tools (Rational Rose), open APIs (Baidu Maps, Tencent Street View, Sina Weibo), static page generation, reporting tools (Crystal Reports), batch processing (Spring Batch), B/S and C/S architectures, Unicode encoding issues, open‑source editors (CKEditor), binary principles, open‑source forum frameworks (Discuz), search engine techniques, software engineering and project management, agile development, workflow engines (OSWorkflow), VPN principles, JSTL/EL expressions, WebService standards (WSDL, SOAP), image handling (upload, preview, size limits), pagination implementation, and basic knowledge of big data and cloud computing.