Package:
A package is a namespace it contains a group of similar types of classes, interfaces, sub-classes. To overcome naming space packages are very helpful.
There are two different types of packages in java
User-defined package
Built-in package
Advantages with packages:
To overcome naming convention packages are very helpful.
Easy to identify classes and interfaces.
Accessing is very easy and provides protection.
Examples:
java.lang (presents fundamental classes)
java.io (input, output functions available)
Creating a package:
To create package choose a name of the package and use package keyword along with the package name.
Syntax:
package nameofpackage;
Compile:
javac –d . <packagename> <filename>
d------> destination folder
. -----> current folder
Example: javac –d . food sample.java
Run:
java packagename. Filename
Example: java food.sample
importing a package:
By using import keyword we can import the existing packages into our class.There are two ways to import package into a class. Importing entire package and another thing importing only required classes from a package.
Example:
Create package with name of food
package food; ( assume it has few classes and interfaces)
import food.eat; (importing only eat class from food package)
import food.*; (importing entire package into a class)
Interview questions:
Define package in java?
Why we are using packages in java?
Why we are using packages in java?
What is the use of packages?
How to compile and execute a package in java?
How many ways we can import the packages into java class?
EmoticonEmoticon