what are all the packages available in Java code example

Example: What is packages in java

Package is a mechanism to group related classes ,interfaces and enums 
in to a single module.
Package can be declared using the following statement :
Syntax : package <package-name>
Coding Convention : package name should be declared in small letters.
package statement defines the namespace.
The main use of package is
1) To resolve naming conflicts
2) For visibility control : We can define classes and interfaces that are 
not accessible outside the class