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Q1-Q10: ♥♦ Top 50+ Core Java Interview Questions and Answers

50+ Core Java interview questions answered for freshers to experienced Java developers. These FAQs have drill down links to more must know Core Java Interview Q&As. Q1. What is the difference between “==” and “equals(…)” in comparing Java String objects? A1. When you use “==” (i.e. shallow comparison), you are

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Q11-Q23: ♦ Top 50+ Core on Java OOP Interview Questions & Answers

The focus is on Java OOP interview questions and answers. Q11. What is the difference between constructors and other regular methods? A11. Constructors must have the same name as the class name and cannot return a value. The constructors are called only once per creation of an object while regular…...

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Q43-Q54: ♦ Top 50+ Core on Java Objects Interview Questions & Answers

Q43. What can you tell about the performance of a HashMap compared to a TreeMap? Which one would you prefer? A43. A balanced tree does have O (log n) performance. The TreeMap class in Java maintains key/value objects in a sorted order by using a red-black tree. A red-black tree…...

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Q37-Q42: ♦ Top 50+ Core on Java Garbage Collection Interview Questions & Answers

As a Java developer, you may not need to know how the JVM works, but the most important topic that you must know is Java Garbage Collection. How the Garbage Collection and object referencing work in Java. Top 50+ Core Java Interview Questions Links: Q01-Q10 | Q11-Q23 on OOP |…...

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Q24-Q36: ♦ Top 50+ Core on Java classes, interfaces and generics interview questions & answers

Focus is on Java classes, interfaces and generics the interview questions and answers style. Java classes and interfaces are the building blocks. Top 50+ Core Java Interview Questions Links: Q01-Q10 | Q11-Q23 on OOP | Q37-Q42 on GC and referencing | Q43-Q54 on Objects Q24. What happens when a parent…...

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04: ♦ Top 10 most common Core Java beginner mistakes

Mistake #1: Using floating point data types like float or double for monetary calculations. This can lead to rounding issues. In the above code, 2, 4, and 5 are correct and 1 and 3 are incorrect usage leading to rounding issues. So, either use BigDecimal properly as shown in 2 and…...

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Java 7: Top 8 new features with examples

There are several small new features and enhancements in Java 7. The major features and enhancements are in Java 8. Let’s look at the Java 7 new features. #1: string in switch statement: Output is: #2 Binary integral literals Output: #3: Underscores for better readability in numeric literals Output: #4:…...

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03: ♦ 9 Core Java Concepts you can’t afford to not know

Q1. How will you go about explaining the following Java concepts to a beginner who is starting to learn Java? 1. Process Vs Threads 2. Heap versus Stack 3. Local variables versus instance variables 4. How do threads communicate with each other? 5. Are Java methods reentrant? 6. Does Java…...

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03: ♦ 21+ Java Servlet interview questions & answers

Q1. What is a Servlet? Is a Servlet inherently multi-threaded? A1. A Servlet is a Java class that runs within a web container in an application server, servicing multiple client requests concurrently forwarded through the server and the web container. The web browser establishes a socket connection to the host…...

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01: ♦ 12 Web basics every Java web developer must know

Q1. HTTP is a stateless protocol, so how do you maintain state? How do you store user data between requests? A1. This is a commonly asked interview question. The “http protocol” is a stateless request/response based protocol. You can retain the state information between different page requests as follows: HTTP…...

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01: ♥♦15+ Java multithreading interview questions & answers

Q1. What is a thread? A1. It is a thread of execution in a program. The JVM allows an application to have multiple threads of execution running concurrently. In the Hotspot JVM there is a direct mapping between a Java Thread and a native operating system (i.e. OS) Thread. The

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♦ 14+ SQL interview Questions & Answers

SQL interview Questions & Answers is a must for any developer as all non-trivial applications need to talk to a database with CRUD operations. Q3 is the most popular. Q1. Can you explain DDL statements in regards to SQL? A1. DDL stands for Data Definition Language, which are statements used…...

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♦ 15 Database design interview Questions & Answers

Q1. What is normalization? When to denormalize? A1. Normalization is a design technique that is widely used as a guide in designing relational databases. Normalization is essentially a two step process that puts data into tabular form by removing repeating groups and then removes duplicated data from the relational tables.…...

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01: ♦♥ 17 Java overview interview questions and answers

Q1. Why use Java? A1. One needs to use the best tool for the job, whether that tool is Java or not. When choosing a technology to solve your business problems, you need to consider many factors like development cost, infrastructure cost, ongoing support cost, robustness, flexibility, security, performance, etc.

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♥♦ Object equals Vs == and pass by reference Vs value

Q1. What is the difference between “==” and equals(..) method when comparing 2 objects? A1.It is important to understand the difference between identity (i.e. ==) comparison, which is a shallow comparison that compares only the object references, and the equals( ) comparison, which is a deeper comparison that compares the

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