1) Basic of Java.
2) OOP's Concepts.
3) String Handling.
4) Exception Handling.
5) Nested Classes.
6) Multithreading.
7) Synchronization.
8) Input and Output.
9) Serialization.
10) Networking.
11) AWT and Event Handling.
12) Swing.
13) Layout Managers.
14) Applet.
15) Collection Framework.
16) JDBC
17) Servlet
18) JSP