Important 100 Android Interview Questions & Answers.


Make use of this frequently asked 100 Android Interview Questions & Answers to crack the interviews easily,
1. What is Android?
Android is a Software for mobile devices which includes an Operating System, middleware and some key applications. The application executes within its own process and its own instance of Dalvik Virtual Machine. Many Virtual Machines run efficiently by a DVM device. DVM executes Java languages bytecode which later transforms into .dex format files.
2. Why cannot you run standard Java bytecode on Android?Android uses Dalvik Virtual Machine (DVM) which requires a special bytecode. We need to convert Java class files into Dalvik Executable files using an Android tool called “dx”. In normal circumstances, developers will not be using this tool directly and build tools will care for the generation of DVM compatible files.
3. What are the different data types used by Android?
The data can be passed between many services and activities using the following data types:
Primitive Data Types: This is used to share the activities and services of an application by using the command as Intent.putExtras(). This primitive data passes the command to show the persistent data using the storage mechanism. These are inbuilt data types that are used with the program. They provide a simple implementation of the type and easy to use commands.
Non-Persistent Objects: It is used to share complex and non-persistent objects. These are user-defined data types that are used for short duration and are also recommended to be used. These types of objects allow the data to be unique but it creates a complex system and increases the delay.
4. What needs to be done in order to set the Android development environment where Eclipse IDE is to be used?
Download the Android SDK from the Android homepage and set the SDK in the preferences. Windows > Preferences > Select Android and enter the installation path of the Android SDK. Alternatively, you may use Eclipse update manager to install all available plugins for the Android Development Tools (ADT)
5. What main components of an Android application?
Activities: They dictate the UI and handle the user interaction to the screen.
Services: They handle background processing associated with an application.
Broadcast Receivers: It handles the communication between Applications and Android Operating system.
Content Providers: They handle data and database management stuff.
6. Where will you declare your activity so the system can access it?
Activity is to be declared in the manifest file. For example:<manifest></manifest><application></application><activityandroid:name=”.MyTestActivity”></activity>
7.Can you deploy executable JARs on Android? Which packaging is supported by Android?
No. Android platform does not support JAR deployments. Applications are packed into Android Package (.apk) using Android Asset Packaging Tool (aapt) and then deployed on to Android platform. Google provides Android Development Tools for Eclipse that can be used to generate an Android Package.
8. Define Android application resource files?
As an Android application developer, you can inject files (XML, JSON, JPEG etc) into the build process and can load them from the code. These injected files are revered as resources.
9. Where can you define the icon for your Activity?
Icon for an Activity is defined in the manifest file.<activityandroid:icon=”@drawable/app_icon”android:name=”.MyTestActivity”></activity>
10.Android application can only be programmed in Java?
False. You can program Android apps in C/C++ using NDK.

Top 100 Tableau Interview Questions and Answers...!


Important Top 100 Tableau Interview Questions and Answers which you can use to crack the interview easily,
1. What is data visualization?
Data visualization refers to the techniques used to communicate data or information by encoding it as visual objects (e.g. points, lines or bars) contained in graphics.
2. Why tableau?
Whether your data is in an on-premise database, a database, a data warehouse, a cloud application or an Excel file, you can analyze it with Tableau. You can create views of your data and share it with colleagues, customers, and partners. You can use Tableau to blend it with other data. And you can keep your data up to date automatically.
3. What is the five main product offered by Tableau company?
Tableau offers five main products: Tableau Desktop, Tableau Server, Tableau Online, Tableau reader and Tableau Public.
4. What are the Filters? How many types of filters are there in Tableau?
The filter is nothing but it is restricted to unnecessary, it is showing exact data. Basically, filters are 3 types.
  • Quick filter
  • Context filter
  • Datasource filter
5. How to remove the All options from a Tableau auto – filter?Right-click filter>>customize>>uncheck show all option
6. What is the benefit of Tableau extract file over the live connection?
The extract can be used anywhere without any connection and you can build your own visualizations without connecting to Database.
7. Max no of tables we can join in Tableau?
We can join max 32 table, it’s not possible to combine more than 32 tables.
8. What are Dimensions and Facts?
Dimensions are nothing but the descriptive text columns and facts are nothing but measures (numerical values) dimentionex:productname city..facts: sales, profit
9. What is a blended axis?
Multiple Measures are shown in a single axis and also all the marks are shown in single pane

  • Drag a dimension in a column
  • Drag the first measure in column
  • Drag 2nd measure in existing axis
  • Us/multiplemeasures_blendedaxes.html
10. How many ways we use parameters in Tableau?
We can use parameters with filters, calculated fields, actions, measure-swap, changing views and auto updates

 Check here the frequently asked 100 Important Tableau Interview Questions & Answers
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Important 100 - ASP.NET Interview Questions & Answers



Make use of this Top 100 ASP.NET Interview Questions & Answers prepared by Credo Systemz’s Placement Team to crack your interview easily..!

1.What is C-Sharp (C#)?

C# is a type-safe, managed and object-oriented language, which is compiled by.Net framework for generating intermediate language (IL).

2. Explain the types of comments in C#?

Below are the types of comments in C# –

  • Single Line Comment Eg : //
  • Multiline Comments Eg: /* */
  • XML Comments Eg : ///

3. List out the differences between Array and ArrayList in C#?

Array stores the values or elements of same data type but ArrayList stores values of different data types.
Arrays will use the fixed length but ArrayList does not use fixed length like an array.

4. Why use “using” in C#?

“Using” statement calls – “dispose” method internally, whenever any exception occurred in any method call and in “Using” statement objects are read-only and cannot be reassignable or modifiable.

5. Explain namespaces in C#?

Namespaces are containers for the classes. We will use
namespaces for grouping the related classes in C#. “Using” keyword can be used for using the namespace in another namespace.

6. Explain “static” keyword in C#?

“Static” keyword can be used for declaring a static member. If the class is made static then all the members of the class are also made static. If the variable is made static then it will have a single instance and the value change is updated in this instance.

7. Why use “finally” block in C#?

“Finally” block will be executed irrespective of exception. So while executing the code in try block when an exception occurs, control is returned to catch block and at last “finally” block will be executed. So the closing connection to database / releasing the file handlers can be kept in “finally” block.

8. Can we have only “try” block without “catch” block in C#?

Yes, we can have only try block without catch block.

9.What is the difference between “out” and “ref” parameters in C#?

“out” parameter can be passed to a method and it need not be initialized where as “ref” parameter has to be initialized before it is used.

10.Explain Jagged Arrays in C#?

If the elements of an array is an array then it’s called a jagged array. The elements can be of different sizes and dimensions.

Check here the remaining 100! Important ASP.NET Interview Questions and Answersframed by experts in the field.

Top 100 Frequently asked AngularJS Interview Questions & Answers..!



1.What is AngularJS?
AngularJS is open source client side MV* (Model – View – Whatever) framework for creating dynamic web applications. It gives life to your static HTML and makes it dynamic with its magic. It extends HTML using directives, expression and data binding techniques to define a powerful HTML template.
2. What are the uses of AngularJS?
Below are the uses of AngularJS –
It uses MVC pattern.
Allows to create our own directive for making components reusable.
Used for two way binding i.e, connecting model and view.
Supports Dependency Injection (DI)
3. Explain what are the key features of Angular.js ?
The key features of angular.js are:
=> Scope
=> Controller
=> Model
=> View
=> Services
=> Data Binding
=> Directives
=> Filters
=> Testable
4. List out the advantages of AngularJS?
Below is the list of advantages of AngularJS –
Code Reusability
Data Binding
Testing
Support
Customize and Extensible
5. What makes angular.js better?
Registering Callbacks: There is no need to register callbacks. This makes your code simple and easy to debug.
Control HTML DOM programmatically: All the application that is created using Angular never have to manipulate the DOM although it can be done if it is required.
Transfer data to and from the UI: Angular.js helps to eliminate almost all of the boilerplate like validating the form, displaying validation errors, returning to an internal model and so on which occurs due to flow of marshaling data.
No initilization code: With angular.js you can bootstrap your app easily using services, which auto-injected into your application in Guice like dependency injection style.
6. Is AngularJS extensible?
Yes! In AngularJS we can create a custom directive to extend AngularJS existing functionalities.
Custom directives are used in AngularJS to extend the functionality of HTML. Custom directives are defined using “directive” function. A custom directive simply replaces the element for which it is activated. AngularJS application during bootstrap finds the matching elements and do one-time activity using its compile() method of the custom directive then process the element using link() method of the custom directive based on the scope of the directive.

 7. Mention what are the advantages of using Angular.js framework?
Advantages of using Angular.js as framework are:
=>Supports two-way data-binding
=>Supports MVC pattern
=>Support static template and angular template
=>Can add the custom directive
=>Supports REST full services
=>Supports form validations
=>Support both client and server communication
=>Support dependency injection
=>Applying Animations
=>Event Handlers
8. How AngularJS is used to handle the security hurdles?
Below is the list of security hurdles handled by AngularJS –
  • Used for preventing CSS attacks
  • Used for preventing XSRF protection
  • Used for preventing HTML injection
9. Who created Angular JS ?
Initially, it was developed by Misko Hevery and Adam Abrons. Currently, it is being developed by Google.
10. Is AngularJS a framework, library or a plugin?
The suitable answer is that its a framework. As its lightweight, so people also get confused between library and framework. AngularJS is open source client-side MVC framework for creating dynamic web applications.

Top 100! DevOps Interview Questions & Answers...!


Important 100! DevOps Interview Questions & Answers:
1. What is DevOps?
It is a newly emerging term in the IT field, which is nothing but a practice that emphasizes the collaboration and communication of both software developers and other information technology (IT) professionals. It focuses on delivering software product faster and lowering the failure rate of releases.
2. What are the core operations of DevOps in terms of development and Infrastructure?
  • The core operations of DevOps are:
  • Application development,
  • Code developing,
  • Code coverage,
  • Unit testing,
  • Packaging,
  • Deployment with infrastructure,
  • Provisioning,
  • Configuration,
  • Orchestration,
  • Deployment.
3. What is Version control and it uses?
It is a system that records changes to a file or set of files over time so that you can recall specific versions later.
Uses of Version control
  • Revert files back to a previous state.
  • Revert the entire project back to a previous state.
  • Compare changes over time.
  • See who last modified something that might be causing a problem
4. List out some popular tools for DevOps?
Some of the popular tools for DevOps are
  • Jenkins
  • Nagios
  • Monit
  • ELK (Elasticsearch, Logstash, Kibana)
  • io
  • Jenkins
  • Docker
  • Ansible
  • Git
  • Collectd/Collectl
5. What is Git?
Git is a Distributed Version Control system (DVCS). It can track changes to a file and allows you to revert back to any particular change.
6. Mention at what instance have you used the SSH?
I have used SSH to log into a remote machine and work on the command line. Beside this, I have also used it to tunnel into the system in order to facilitate secure encrypted communications between two untrusted hosts over an insecure network.
7. Explain how DevOps is helpful to developers?
DevOps can be helpful to developers to fix the bug and implement new features quickly. It also helps for clearer communication between the team members.
8. Mention what are the types of Http requests?
The types of Http requests are
  • GET
  • HEAD
  • PUT
  • POST
  • PATCH
  • DELETE
  • TRACE
  • CONNECT
  • OPTIONS
9. What Are Vagrant And Its Uses?
Vagrant used the virtual box as the hypervisor for virtual environments and in the current scenario, it is also supporting the KVM. Kernel-based Virtual Machine
A vagrant is a tool that can create and manage environments for testing and developing software.
10. List The Agile Methodology Of DevOps?
  • DevOps is a process
  • Agile is same as DevOps
  • A separate group for are framed
  • It is problem-solving
  • Developers managing production
  • DevOps is development-driven release management

100+ Important Machine Learning Interview Questions & Answers.!

Machine Learning Interview Questions & Answers

 Make use of this frequently asked 100 Machine Learning Interview Questions & Answers collected by our placement team,

 Useful Link: Machine Learning Topics Free PDF
1. What is machine learning?
In answering this question, try to show you understand of the broad applications of machine learning, as well as how it fits into AI. Put it into your own words, but convey your understanding that machine learning is a form of AI that automates data analysis to enable computers to learn and adapt through experience to do specific tasks without explicit programming
2. What is candidate sampling in machine learning?
A training-time optimization in which a probability is calculated for all the positive labels, using, for example, softmax, but only for a random sample of negative labels. For example, if we have an example labeled beagle and dog candidate sampling computes the predicted probabilities and corresponding loss terms for the beagle and dog class outputs in addition to a random subset of the remaining classes (cat, lollipop, fence).
3. Mention the difference between Data Mining and Machine learning?
Machine learning relates to the study, design, and development of the algorithms that give computers the capability to learn without being explicitly programmed. While data mining can be defined as the process by which the unstructured data tries to extract knowledge or unknown interesting patterns. During this processing machine, learning algorithms are used.
4. What is A/B testing in Machine Learning?
A statistical way of comparing two (or more) techniques, typically an incumbent against a new rival. A/B testing aims to determine not only which technique performs better but also to understand whether the difference is statistically significant. A/B testing usually considers only two techniques using one measurement, but it can be applied to any finite number of techniques and measures.
5. Explain How We Can Capture The Correlation Between Continuous And Categorical Variable?
Yes, it is possible by using ANCOVA technique. It stands for Analysis of Covariance.
It is used to calculate the association between continuous and categorical variables.
6. What is ‘Overfitting’ in Machine learning?
In machine learning, when a statistical model describes random error or noise instead of the underlying relationship ‘overfitting’ occurs. When a model is excessively complex, overfitting is normally observed, because of having too many parameters with respect to the number of training data types. The model exhibits poor performance which has been overfitted.
7. Why does overfitting happen?
The possibility of overfitting exists as the criteria used for training the model is not the same as the criteria used to judge the efficacy of a model.
8. How can you avoid overfitting?
By using a lot of data overfitting can be avoided, overfitting happens relatively as you have a small dataset, and you try to learn from it. But if you have a small database and you are forced to come with a model based on that. In such a situation, you can use a technique known as cross-validation. In this method the dataset splits into two section, testing and training datasets, the testing dataset will only test the model while, in the training dataset, the data points will come up with the model.
In this technique, a model is usually given a dataset of a known data on which training (training data set) is run and a dataset of unknown data against which the model is tested. The idea of cross-validation is to define a dataset to “test” the model in the training phase.
9. Explain Principal Component Analysis (PCA).
PCA is a dimensionality-reduction technique which mathematically transforms a set of correlated variables into a smaller set of uncorrelated variables called principal components.
10. What value do you optimize when using a support vector machine (SVM)?
For a linear function, SVM optimizes the product of input vectors as well as the coefficients. In other words, the algorithm with the linear function can be restructured into a dot-product.

100! Important Hadoop Interview Questions

Hadoop Interview Questions and Answers



Collect the important Hadoop interview questions and answers from top MNCs, Make use of it to crack the interview easily

1. What is Apache Hadoop?

Hadoop is an open source software framework for distributed storage and distributed processing of large data sets. Open source means it is freely available and even we can change its source code as per our requirements. Apache Hadoop makes it possible to run applications on the system with thousands of commodity hardware nodes. It’s distributed file system has the provision of rapid data transfer rates among nodes. It also allows the system to continue operating in case of node failure.

2. Main Components of Hadoop?
Storage layer – HDFS

Batch processing engine – MapReduce

Resource Management Layer – YARN

HDFS – HDFS (Hadoop Distributed File System) is the storage unit of Hadoop. It is responsible for storing different kinds of data as blocks in a distributed environment. It follows master and slave topology.
Components of HDFS are NameNode and DataNode
MapReduce – For processing large data sets in parallel across a hadoop cluster, Hadoop MapReduce framework is used. Data analysis uses a two-step map and reduce process.
YARN – YARN (Yet Another Resource Negotiator) is the processing framework in Hadoop, which manages resources and provides an execution environment to the processes.
Main Components of YARN are Node Manager and Resource Manager

3. Why do we need Hadoop?

Storage – Since data is very large, so storing such huge amount of data is very difficult.
Security – Since the data is huge in size, keeping it secure is another challenge.
Analytics – In Big Data, most of the time we are unaware of the kind of data we are dealing with. So analyzing that data is even more difficult.
Data Quality – In the case of Big Data, data is very messy, inconsistent and incomplete.
Discovery – Using a powerful algorithm to find patterns and insights are very difficult.

4. What are the four characteristics of Big Data?

Volume: The volume represents the amount of data which is growing at an exponential rate i.e. in Petabytes and Exabytes.
Velocity: Velocity refers to the rate at which data is growing, which is very fast. Today, yesterday’s data are considered as old data. Nowadays, social media is a major contributor in the velocity of growing data.
Variety: Variety refers to the heterogeneity of data types. In another word, the data which are gathered has a variety of formats like videos, audios, csv, etc. So, these various formats represent the variety of data.
Value: It is all well and good to have access to big data but unless we can turn it into a value it is useless.

5. What are the modes in which Hadoop run?

Local (Standalone) Mode – Hadoop by default run in a single-node, non-distributed mode, as a single Java process.
Pseudo-Distributed Mode – Just like the Standalone mode, Hadoop also runs on a single-node in a Pseudo-distributed mode.
Fully-Distributed Mode – In this mode, all daemons execute in separate nodes forming a multi-node cluster. Thus, it allows separate nodes for Master and Slave.

6. Explain about the indexing process in HDFS.

Indexing process in HDFS depends on the block size. HDFS stores the last part of the data that further points to the address where the next part of data chunk is stored.

7. What happens to a NameNode that has no data?

There does not exist any NameNode without data. If it is a NameNode then it should have some sort of data in it.

8. What is Hadoop streaming?

Hadoop distribution has a generic application programming interface for writing Map and Reduce jobs in any desired programming language like Python, Perl, Ruby, etc. This is referred to as Hadoop Streaming. Users can create and run jobs with any kind of shell scripts or executable as the Mapper or Reducers.

9. What is a block and block scanner in HDFS?

Block – The minimum amount of data that can be read or written is generally referred to as a “block” in HDFS. The default size of a block in HDFS is 64MB.

Block Scanner – Block Scanner tracks the list of blocks present on a DataNode and verifies them to find any kind of checksum errors. Block Scanners use a throttling mechanism to reserve disk bandwidth on the datanode.

10. What is a checkpoint?

Checkpoint Node keeps track of the latest checkpoint in a directory that has same structure as that of NameNode’s directory. Checkpoint node creates checkpoints for the namespace at regular intervals by downloading the edits and fsimage file from the NameNode and merging it locally. The new image is then again updated back to the active NameNode.


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