DEV Community: Pramod Bablad

Spring IoC Container

Pramod Bablad — Thu, 03 Aug 2023 06:52:23 +0000

Spring IoC Container

1) Spring IoC container forms the core of the Java Spring Framework.
2) It is responsible for instantiating, configuring and managing the beans in your spring application.
3) It uses configuration metadata to manage the beans.
4) Configuration metadata can be supplied through XML file or through Java annotations or through Java Code.
5) It uses configuration metadata and POJO classes to set up an application ready for use.

See more at https://javaconceptoftheday.com/spring-ioc-container/

Java Array Cheat Sheet

Pramod Bablad — Thu, 27 Jul 2023 12:01:32 +0000

Quick reference guide for arrays in Java.

See more at https://javaconceptoftheday.com/java-array-cheat-sheet/

Most Likely Java Array Interview Questions And Answers

Pramod Bablad — Mon, 24 Apr 2023 08:05:14 +0000

1) What is an array?
2) What are the different ways to create arrays in Java?
3) What is ArrayStoreException in Java? When you will get this exception?
4) Can you pass the negative number as an array size?
5) Can you change the size of an array once you define it?
6) What is an anonymous array? Give example?
7) What is the difference between int[] a and int a[] ?
8) There are two array objects of int type. One is containing 100 elements and another one is containing 10 elements. Can you assign an array of 100 elements to an array of 10 elements?
9) “int a[] = new int[3] {1, 2, 3}” – is it a legal way of defining the arrays in Java?
10) What are the differences between Array and ArrayList in Java?
11) Where the arrays are stored in the memory?
12) What are the different ways of copying an array into another array?
13) What are jagged arrays in Java? Give example?
14) How do you check the equality of two arrays in Java?
15) What is ArrayIndexOutOfBoundsException in Java? When it occurs?
16) How do you sort the array elements?
17) How do you find the intersection of two arrays in Java?
18) What are the different ways of declaring multidimensional arrays in Java?
19) While creating the multidimensional arrays, can you specify an array dimension after an empty dimension?
20) How do you search an array for a specific element?
21) What value does array elements get, if they are not initialized?
22) What are the different ways to iterate over an array in java?
23) How do you convert a List or Set to an array?
24) What is the time complexity of different operations on arrays?
25) What are the main drawbacks of the arrays in Java?
26) How do you find duplicate elements in an array?
27) How do you find a missing number in an array of integers if it contains elements from 1 to n where n is the number of elements?
28) How do you remove duplicate elements from an array?
29)How do you find the most frequent element in an array?
30) How do you merge two unsorted arrays into single sorted array?
31) How do you merge two sorted or unsorted arrays into single sorted array without duplicates?
32) How do you find smallest and second smallest element in an integer array?

See the answers at https://javaconceptoftheday.com/java-array-interview-questions-and-answers/

Java HashSet Internal Working

Pramod Bablad — Wed, 19 Apr 2023 11:05:51 +0000

HashSet internally uses HashMap to store it’s elements. Whenever you create a HashSet object, one HashMap object associated with it is also created. This HashMap object is used to store the elements you enter in the HashSet. The elements you add into HashSet are stored as keys of this HashMap object. The value associated with those keys will be a constant.

See more at https://javaconceptoftheday.com/how-hashset-works-internally-in-java/

Most Likely Java Exception Handling Interview Questions

Pramod Bablad — Mon, 17 Apr 2023 08:22:17 +0000

1) What is an exception?
2) How the exceptions are handled in Java?
3) What is the difference between error and exception in Java?
4) Can we keep other statements in between try, catch and finally blocks?
5) Can we write only try block without catch and finally blocks?
6) There are three statements in a try block – statement1, statement2 and statement3. After that there is a catch block to catch the exceptions occurred in the try block. Assume that exception has occurred in statement2. Does statement3 get executed or not?
7) What is unreachable catch block error?
8) Explain the hierarchy of exceptions in Java?
9) What are run time exceptions in Java. Give example?
10) What is OutOfMemoryError in Java?
11) what are checked and unchecked exceptions in Java?
12) What is the difference between ClassNotFoundException and NoClassDefFoundError in Java?
13) Can we keep the statements after finally block If the finally block is returning the control?
14) Does finally block get executed If either try or catch blocks are returning the control?
15) Can we throw an exception manually? If yes, how?
16) What is Re-throwing an exception in Java?
17) What is the use of throws keyword in Java?
18) Why it is always recommended that clean up operations like closing the DB resources to keep inside a finally block?
19) What is the difference between final, finally and finalize in Java?
20) How do you create customized exceptions in Java?
21) What is ClassCastException in Java?
22) What is the difference between throw, throws and throwable in Java?
23) What is StackOverflowError in Java?
24) Can we override a super class method which is throwing an unchecked exception with checked exception in the sub class?
25) What are chained exceptions in Java?
26) Which class is the super class for all types of errors and exceptions in Java?
27) What are the legal combinations of try, catch and finally blocks?
28) What is the use of printStackTrace() method?
29) Give some examples to checked exceptions?
30) Give some examples to unchecked exceptions?
31) Do you know try-with-resources blocks? Why do we use them? When they are introduced?
32) What are the benefits of try-with-resources?
33) What are the changes made to exception handling from Java 7?
34) What are the improvements made to try-with-resources in Java 9?
35) What are the differences between StackOverflowError and OutOfMemoryError In Java?

See the answers at https://javaconceptoftheday.com/java-exception-handling-interview-questions-and-answers/

Java Collections Cheat Sheet

Pramod Bablad — Wed, 21 Dec 2022 09:19:58 +0000

Java Collections Cheat Sheet

Here is the Java collections cheat sheet. You can use it as quick reference guide to prepare for the interviews.

See more at https://javaconceptoftheday.com/java-collections-cheat-sheet/

Java 8 Tutorials

Pramod Bablad — Tue, 13 Dec 2022 06:57:09 +0000

Java 8 Tutorials

1) Java 8 Lambda Expressions : https://javaconceptoftheday.com/java-8-lambda-expressions/

2) Java 8 Functional Interfaces : https://javaconceptoftheday.com/java-8-functional-interfaces/

3) Java 8 Method References : https://javaconceptoftheday.com/java-8-method-references/

4) Java 8 Interface Changes : https://javaconceptoftheday.com/java-8-interface-changes-default-methods-and-static-methods/

5) Java 8 Streams : https://javaconceptoftheday.com/java-8-streams-beginners-guide/

6) Java 8 Collectors : https://javaconceptoftheday.com/java-8-collectors-tutorial/

7) Java 8 Optional Class : https://javaconceptoftheday.com/java-8-optional-class/

8) Java 8 Spliterator : https://javaconceptoftheday.com/java-8-spliterator/

9) Java 8 StringJoiner, String.join() And Collectors.joining() : https://javaconceptoftheday.com/java-8-stringjoiner-string-join-collectors-joining/

10) Solving Real Time Queries Using Java 8 Features -Employee Management System : https://javaconceptoftheday.com/solving-real-time-queries-using-java-8-features-employee-management-system/

Java Exception Handling Cheat Sheet

Pramod Bablad — Tue, 06 Dec 2022 07:18:27 +0000

Java Exception Handling Cheat Sheet

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Here is the Java exception handling cheat sheet. You can use it as quick reference guide to prepare for the interviews.

See more at https://javaconceptoftheday.com/java-exception-handling-cheat-sheet/

Java 9 New Features

Pramod Bablad — Wed, 30 Nov 2022 08:19:06 +0000

Java 9 New Features

1) Java 9 Interface Private Methods : https://javaconceptoftheday.com/java-9-interface-private-methods/

2) Java 9 JShell – REPL Tool : https://javaconceptoftheday.com/java-9-jshell-repl-tool/

3) Java 9 Immutable Collections : https://javaconceptoftheday.com/java-9-immutable-collections/

4) Java 9 Stream API Improvements : https://javaconceptoftheday.com/java-9-stream-api-improvements-takewhile-dropwhile-ofnullable-and-iterate/

5) Java 9 Try With Resources Improvements : https://javaconceptoftheday.com/java-9-try-with-resources-improvements/

6) Java 9 Diamond Operator Improvements : https://javaconceptoftheday.com/java-9-diamond-operator-improvements/

7) Java 9 @SafeVarargs Annotation Changes : https://javaconceptoftheday.com/java-9-safevarargs-annotation-changes/

8) Java 9 Underscore Changes : https://javaconceptoftheday.com/java-9-underscore-changes/

9) Java 9 Optional Class Improvements : https://javaconceptoftheday.com/java-9-optional-class-improvements/

Java OOP Concepts Cheat Sheet

Pramod Bablad — Thu, 15 Sep 2022 09:32:28 +0000

Inheritance, Abstraction, Polymorphism and Encapsulation quick reference guide.

See more at https://javaconceptoftheday.com/java-oop-concepts-cheat-sheet/

Solving Real Time Queries Using Java 8 Features -Employee Management System

Pramod Bablad — Wed, 13 Jul 2022 07:53:20 +0000

1) How many male and female employees are there in the organization?
2) Print the name of all departments in the organization?
3) What is the average age of male and female employees?
4) Get the details of highest paid employee in the organization?
5) Get the names of all employees who have joined after 2015?
6) Count the number of employees in each department?
7) What is the average salary of each department?
8) Get the details of youngest male employee in the product development department?
9) Who has the most working experience in the organization?
10) How many male and female employees are there in the sales and marketing team?
11) What is the average salary of male and female employees?
12) List down the names of all employees in each department?
13) What is the average salary and total salary of the whole organization?
14) Separate the employees who are younger or equal to 25 years from those employees who are older than 25 years?
15) Who is the oldest employee in the organization? What is his age and which department he belongs to?

See the Java 8 code at https://javaconceptoftheday.com/solving-real-time-queries-using-java-8-features-employee-management-system/

Java New String Methods – From Java 8 To Java 17

Pramod Bablad — Mon, 11 Jul 2022 07:30:13 +0000

Strings are the most used data type in Java. Almost every application in Java makes use of strings. That’s why strings are treated with special attention in Java. From time to time, new methods are added to String class so that working with strings becomes effortless and simple. join() in Java 8, chars() and codePoints() in Java 9, isBlank(), lines(), repeat(), strip(), stripLeading() and stripTrailing() in Java 11, indent(), transform(), describeConstable() and resolveConstantDesc() in Java 12, formatted(), stripIndent() and translateEscapes() in Java 15 are some new Java string methods.

See more at https://javaconceptoftheday.com/java-new-string-methods-with-examples/