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01: ♦ 17 FAQ Java Collection Framework (i.e. JCF) interview Q&As on differences between X & Y

Java Collection interview questions and answers and Java String class interview Q&As are must know as you can’t write any decent Java application without these 2 APIs. This post focuses on Java Collection interview Q&As on differences between X and Y. These Q&As are discussed in more detail in the…...

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Posted in Collection and Data structures, Differences Between X & Y, FAQs Core Java, member-paid
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12: ♦ 5 Java multithreading scenarios interview questions answered

This extends Q1. Can you give some scenarios where you had used multi-threading in Java applications? Q2. Can you give some scenarios where you used the synchronized keyword in Java? A2. Firstly, you need to assume that your code is always going to be accessed by multiple threads. Scenario 1:…...

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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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02: ♦ Java 8 Streams, lambdas, intermediate vs terminal ops, and lazy loading with simple examples

A stream is an infinite sequence of consumable elements (i.e a data structure) for the consumption of an operation or iteration. Any Collection<T> can be exposed as a stream. It looks complex, but once you get it, it is very simple. The operations you perform on a stream can either…...

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Posted in Collection and Data structures, FP, Java 8, Java 8 Tutorial, member-paid
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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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8 Java Annotations interview Questions and Answers

Q1. Are annotations a compile time or run-time feature? A1. You can have either compile-time or run-time annotations. @Override is a simple compile-time annotation to catch little mistakes like typing tostring( ) instead of toString( ) in a subclass. If you remove the toString( ) method in Class A or…...

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♦ Java exception handling interview questions and answers

Q1. What is the difference between a runtime exception and a checked exception? A1. You must either catch or throw a checked exception. The unchecked exception (aka Runtime exception) does not have to be explicitly handled. Q. So, when to use checked exception, and when to use unchecked exception? A.…...

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Mocks, stubs, domain, and anemic objects interview Q&A

Q1. What are mock objects? A1. Mock objects are used in unit testing to ensure that your tests don’t fail due to volatility of the data changes. There are mocking frameworks like EasyMock, Mockito, and PowerMock. The key point to remember regarding mock objects is the ability of the mock…...

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02: ♦ 9 Java Collection interview Q&As on choosing the right data structure

Java Collection interview Q&As on choosing the right data structure as it is vital to choose the right data structure to get the job done with proper space vs performance trade-offs. Q1. What are the common data structures, and where would you use them? A1. Arrays, Lists, Sets, Maps, Trees,…...

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♦ Java development process interview Q&A

No right or wrong answers. The depth and quality of the answers will can prove your seniority and experience. Q1. What are the SDLC activities you perform as a Java developer? A1. Don’t get overwhelmed by this activities list. This proves why employers favor experience to just academic qualifications alone.…...

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05: ♦ 9 Java multithreading Q&As on concepts like blocking, sequencing, preempting & daemon threads

Java multithreading Q&As on concepts like blocking, and debugging blocked threads. How do you sequence threads? what do you understand by the term preemptive scheduling? Q1. What are the different ways a Java thread gets blocked or suspended? How will you debug Java threading issues? A1. 1. It has been…...

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