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create a package in java with example steps for creating user defined package in java
User Defined Packages :
Definition Of User Defined Package :
User defined packages are those which are developed by java programmer and supplied
as a part of their project to deal common specific requirements.
If we want to give any class name or interface name to many number of java programmer
then such type of classes and interfaces must be placed in a packages. In other words the
package classes and interfaces must be placed in a package’s. In other words the
packages classes and interfaces must be placed in a package. In other words the package
classes and interfaces are meant for common access.
What are all classes the guide lines are followed by sun micro system for development
of pre defined packages, same guidelines will be followed by us for development of user
Creating a user defined package is nothing but creating those package names as directory /
folders in the current working machine.
For Example : java.awt.event.*;
In the above package, java is one of the root of the root directory, awtis one of the sub
directory in java directory and event is sub directory in awt directory.
Java is sub directory in the current working machines of sun micro system. Similarly p1.p2.p3.*; in the statement p1 is called directory, p2 is sub directory and p3 is called sub – sub directory in our current working machine.
Syntax for creating package:
Package pack1[pack2[pack3…….[pack n]]];
In the above syntax
1) Package is keyword used for developing user defined package.
2) Pack1, pack2……pack n represents java valid variable names and they are treated
as name of user defined packages.
3) Pack2, pack3……pack n represents name of the sub packages and whose
specification is optional.
4) Pack1 represents an upper package or outer package and whose specifications is
For Example :
Guide lines or steps for development of user defined package:
Sun micro system has prescribed the following guidelines for development of user defined packages.
1) Choose an appropriate package for placing the common classes and interfaces and
ensure that the package statement must be the first executable statement.
2) Choose an appropriate class name / interface name and ensure that whose modifier
must be public.
3) The modifier of the constructor of the class which is present in the package must be
4) The modifier of the method of class / interface must be public (this rule is optional in the
case of interface’s_ because every method of interface is public.
5) Whichever class name / interface name present in the package, the class name/ interface
name must be given as file name an extension (.java).
6) At any point either we need to write a class definition or interface definition in the
package, but not both the definition in the single window in the same package.
// Create a package pack1 and place class called Demo
Public class Demo
System.out.println(“user defined package”);
Public void display()
System.out.println(“user defined display method”);
Public interface Test
Public void show();
Compiling package classes and interface.
For Compiling package classes and interfaces, we use the following
java –d . Demo.java
Then we can find under Pack1 package Demo.class and Test.class as follows