SFR | e-Content Development Program

FAQ

1. Can we instantiate an interface?
2. Can we create an object for an interface?
3. Can we define a variable in an interface ?and what type it should be ?
4. What modifiers are allowed for methods in an Interface?
5. Does importing a package imports the sub packages as well? E.g. Does importing com.bob.* also import com.bob.code.*?
6. What do you understand by package access specifier?
7. What is use of interface?
8. Is it is necessary to implement all methods in an interface?

Java Packages and Interfaces

Defining Package

Java provides a mechanism for partitioning the class name space into more manageable chunks. To create a package, include a package command as the first statement in a Java source file. … Read more »
Importing Package

Java includes the import statement to bring certain classes, or entire packages, into visibility. Once imported, a class can be referred to directly, using only its name… Read more »
Package example

Example program to define and import a package. … Read more »
Defining Interfaces

Interface can be used to specify what a class must do, but not how it does it. Interfaces are similar to classes, but they lack instance variables, and their methods are declared without any body. … Read more »
Implementing Interface

Once an interface has been defined, one or more classes can implement that interface. To implement an interface, include the implements clause in a class definition, and then create the methods defined by the interface … Read more »
Extending Interfaces

One interface can inherit another by use of the keyword extends. The syntax is the same as for inheriting classes. … Read more »

FAQ

Java Packages and Interfaces

Defining Package

Importing Package

Package example

Defining Interfaces

Implementing Interface

Extending Interfaces