added code structure and Readme in java dir

Author: akrishna0

Java/Enumeration.class renamed to Java/Codes/Enumeration.class

@@ -0,0 +1,17 @@
+# JAVA Guide
+
+## Naming Conventions
+
+### Class and Interface
+- They starts with Capitals letter.
+Example : Calculator, Runable, Object.
+
+### Variables and Methods
+- Starts with small letter.
+
+Example : marks, show(), getPrice(), setPrice() etc.
+
+### Constants
+- The whole word is in Capitals.
+
+Example : PI,  BRAIN, MY_DATA, RAM, CPU_UTILIZATION etc.