Java Developers need an extensive range of skills, from in-depth knowledge of the basics to a thorough understanding of the current developments. Experts in Java are also expected to know how the development process works and how to transition between the environments where the code runs.A well-rounded Java Developer has proficiency in Java full stack developer skills and Java backend developer skills.Some of the Java Developer key skills include:Proficiency in Java, with a good understanding of its ecosystemsSound knowledge ofObject-Oriented Programming (OOP)Patterns and ConceptsFamiliarity with different design and architectural patternsSkill for writing reusable Java librariesKnowhow of Java concurrency patternsBasic Understanding of the concepts of MVC (Model-View-Controller) Pattern, JDBC (Java Database Connectivity), and RESTful web servicesExperience in working with popular web application frameworks like Play and SparkRelevant Knowledge of Java GUI frameworks like Swing, SWT, AWT according to project requirementsAbility to write clean, readable Java codeBasic knowhow of class loading mechanism in JavaExperience in handling external and embedded databasesUnderstanding basic design principles behind a scalable applicationSkilled at creating database schemas that characterize and support business processesBasic knowledge ofJVM (Java Virtual Machine), its drawbacks, weaknesses, and workaroundsImplementing automated testing platforms and unit testsIn-depth knowledge of code versioning tools, for instance, GitUnderstanding of building tools like Ant, Maven, Gradle, etc