Skip to main content

Java Package Interview Questions


Java Package




1. What is the purpose of package in Java?

A package is used to encapsulate a group of classes, interfaces and sub-packages. Often, it is a hierarchical structure of storing information. It is easier to organize the related classes and subpackages in this manner. A Package also provides access protection for classes andinterfaces. A package also helps in removing naming collision.

2. What is java.lang package?

In Java, java.lang package contains the classes that are fundamental to the design of Java programming language. The most important class in this package is Object class. It also contains wrapper classes like- Integer, Boolean, Character etc. It provides Math class for mathematical operations.

3. Which is the most important class in Java?

It is an open-ended question with many answers. In my view, Object class is the most important class of Java programming language. It is the root of all the classes in Java. It provides some very important and fundamental methods.

4.Is it mandatory to import java.lang package every time?

No. By default, JVM loads it internally.

5. Can you import same package or class twice in your class?

If we import same package multiple times in a class, compiler includes it only once. So neither JVM nor Compiler gives any error/warning on including a package multiple times. If you have two classes with same name, then you may get name collision on importing the class erroneously. JVM internally loads the class only one time.

6. What is a static import in Java?

Static import is similar to normal import declaration. Normal import allows us to import classes from packages without using package qualifier. Static import allows us to import static members from a class without using class qualifier.

7.What is the difference between import static com.test.Fooclass and import com.test.Fooclass?

First import is a static import and the second import is normal import of a class. First import allows us to import static members of class.








Labels:

Comments

Post a Comment

Popular posts from this blog

DOCKER Interview questions

DOCKER 1. What is Docker? Docker is Open Source software. It provides the automation of Linux application deployment in a software container. We can do operating system level virtualization on Linux with Docker. Docker can package software in a complete file system that contains software code, runtime environment, system tools, & libraries that are required to install and run the software on a server. 2. What is the difference between Docker image and Docker container? Docker container is simply an instance of Docker image. A Docker image is an immutable file, which is a snapshot of container. We create an image with build command. When we use run command, an Image will produce a container. In programming language, an Image is a Class and a Container is an instance of the class. 3. How will you remove an image from Docker? We can use docker rmi command to delete an image from our local system. Exact command is: % docker rmi <Image Id> If we want to fin
2 comments
Read Next»

Cloud Computing Interview Questions

Cloud Computing 1. What are the benefits of Cloud Computing? There are ten main benefits of Cloud Computing: Flexibility : The businesses that have fluctuating bandwidth demands need the flexibility of Cloud Computing. If you need high bandwidth, you can scale up your cloud capacity. When you do not need high bandwidth, you can just scale down. There is no need to be tied into an inflexible fixed capacity infrastructure. Disaster Recovery : Cloud Computing provides robust backup and recovery solutions that are hosted in cloud. Due to this there is no need to spend extra resources on homegrown disaster recovery. It also saves time in setting up disaster recovery. Automatic Software Updates : Most of the Cloud providers give automatic software updates. This reduces the extra task of installing new software version and always catching up with the latest software installs. Low Capital Expenditure : In Cloud computing the model is Pay as you Go. This means there is very
Post a Comment
Read Next»

Microservices Interview Questions

Microservices Interview Questions 1. What is a Microservice in Java? A Microservice is a small and autonomous piece of code that does one thing very well. It is focused on doing well one specific task in a big system. It is also an autonomous entity that can be designed, developed and deployed independently. Generally, it is implemented as a REST service on HTTP protocol, with technology-agnostic APIs. Ideally, it does not share database with any other service. 2. What are the benefits of Microservices architecture? Microservices provide many benefits. Some of the key benefits are: 1.      Scaling : Since there are multiple Microservices instead of one monolith, it is easier to scale up the service that is being used more. Eg. Let say, you have a Product Lookup service and Product Buy service. The frequency of Product Lookup is much higher than Product Buy service. In this case, you can just scale up the Product Lookup service to run on powerful hardware with multipl
Post a Comment
Read Next»