Simplify360 Java Developer Interview Questions and Answers

Q1. What is the difference between ==and .equals() in java?
Ans. 
In Java, == compares memory addresses while .equals() compares the actual content of objects.
• == compares memory addresses of objects, while .equals() compares the actual content of objects.

• == is used to compare primitive data types, while .equals() is used to compare objects.

• Example: String str1 = new String("hello"); String str2 = new String("hello"); str1 == str2 will be false, but str1.equals(str2) will be true.
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Q2. ==compares object references, while .equals() compares object values in java.
Ans. 
In Java, == compares object references, while .equals() compares object values.
• Use == to compare if two object references point to the same memory location.

• Use .equals() to compare if two objects have the same values.

• Example: String str1 = new String("hello"); String str2 = new String("hello"); str1 == str2 will be false, but str1.equals(str2) will be true.
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Q1. In trend java questions
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Q1. Advance java questions, questions related to microservice and java 8
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Q1. Where do you see yourself in 5 years?
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They will test on your pations

You have crack the coding test within time..

Q1. What is the purpose of the volatile keyword?
Ans. 
The volatile keyword in Java is used to indicate that a variable's value will be modified by different threads.
• Ensures visibility of changes made by one thread to other threads

• Prevents compiler optimizations that could reorder instructions

• Useful for variables accessed by multiple threads without synchronization

• Example: volatile boolean flag = true;
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Q2. It ensures visibility nd prevents instruction reordering in multi-threading.
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Q1. What is JAVA Full Form?
Ans. 
JAVA stands for Java Virtual Machine
• JAVA stands for Java Virtual Machine

• It is a programming language that follows the principle of 'write once, run anywhere'

• Java code is compiled into bytecode which can run on any platform with Java Virtual Machine (JVM)

• Examples of Java applications include web applications, mobile apps, and enterprise software
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Q2. JAVA stands for Just Another Virtual Accelerator.
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Q1. What is the D/W Hashmap and ConcurrentHashmap in Java?
Ans. 
D/W Hashmap and ConcurrentHashmap are both implementations of the Map interface in Java, with the latter being thread-safe.
• D/W Hashmap stands for 'Doubly-Linked Hashmap' and is a custom implementation of a hashmap in Java that maintains insertion order.

• ConcurrentHashmap is a thread-safe implementation of the Map interface in Java, allowing multiple threads to access and modify it concurrently without causing data corru
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Q2. HashMap is not thread-safe, while concurrentHashMap is thread-safe.
Ans. 
HashMap is not synchronized and not thread-safe, while ConcurrentHashMap is thread-safe and allows concurrent access.
• HashMap is not synchronized, so it is not safe to use in a multi-threaded environment without external synchronization.

• ConcurrentHashMap uses internal synchronization mechanisms to ensure thread safety, allowing multiple threads to access and modify it concurrently.

• ConcurrentHashMap is designed to handle...read more
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