Core Java is the minimum requirement to be a Java programmer.

Introduction to Java
Evolution of Java
Object Oriented Programming Structure
Client Side & Server Side Programming
Platform Independency & Portability
Security
JVM, JRE and JDK
Structure of a Java Class
Introduction to JAR
Naming conventions and Data Types

OOPS Implementations
Classes and Objects
Understanding Memory Structure
Understanding Class loading and execution flow
Argument Passing Mechanism
Usage of this keyword
Inheritance
Interfaces
Has-A relation
Packages

Exception Handling & Mulitthreading
Difference b/w exceptions and errors
Use of try, catch, throw, throws and finally
Checked and unchecked exceptions
Defining and using custom exceptions
Understanding the roles of Thread & Runnable
Synchronization & Inter thread communication
Interrupting Threads
ThreadGroup & Daemon threads

Input Output
Streams and their advantages
Use of common byte & character streams
Serialization & Deserialization
Interaction to the file system
Use of Scanner

Networking
Connection Oriented vs Connection less networking
Understanding the concepts of socket & port
Implementing a chat application using TCP/IP
Implementing UDP based sender and receiver
Implementing HTTP client

Collection
Introduction to collection framework
Use of List & Set based collections
Use of Maps
Iterator and ListIterator
Introduction to Multithreading
Difference b/w Iterator & Enumeration
Role of equals() & hashCode() methods
Comparable vs Comparator
Use of Generics in collection

 
JDBC
Types of JDBC drivers
Statement vs PreparedStatement
Performing CRUD operations
Batch execution of queries
Use of CallableStatement
Use of ResultSetMetaData
Use of DatabaseMetaData

Reflection
Understanding the role of Class object
Understanding dynamic class loading
Fetching the information of class members dynamically
Creating objects indirectly
Invoking methods indirectly
Accessing private members of classes