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Java job interview questions

• Name all methods of class java.lang.Object
• getClass
• equals, hashCode
• clone
• toString
• finalize
• wait, notify, notifyAll
• What are the differences between final, finally, and finalize?
• What are the literals?
• What are the modifiers?
• What are the differences between checked and unchecked exceptions?
• What is synchronized?
• What is the purpose of volatile?
• ArrayList vs LinkedList
• How to remove an element from an ArrayList during iteration?
• What is the structure of the Java Collections Framework? Why is Map not a Collection?
• How does a HashMap work?
• How do you sort a Set or Map?
• How do you create an immutable collection?
• Which collections should be used in a multi-threaded environment?
• What are the primitive data types?
• What types exist in Java?
• What is static?
• What are the different access modifiers?
• Describe the process of creating an instance of a class
• Does new Integer(128) == 128?
• Does new String("Hello_42") == "Hello_" + 42?
• Are parameters passed by reference or by value in Java?
• What types of references exist in Java?
• What is inside .class file?
• How much memory does an object occupy?
• How does garbage collection work?
• What can you do with a variable holding null?
• What is an enum?
• What is the purpose of class loaders?
• What are the default class loaders?
• Overload vs override
• How to write a singleton?
• What is the difference between interface and @interface?
• Why do we need the default keyword?
• When does Class.getClassLoader return null?
• What is the order of modifiers
• What is short-circuiting in logical operators?
• What are the integer bitwise operators?
• How can you determine if A is a subtype of B?
• What is Type Erasure?
• How can you restrict the type of a generic parameter?
• What are Covariance and Contravariance?
• What is a bridge method?
• What is heap pollution?
• How does type inference work?
• What are string classes available in Java?
• How to iterate over a string?
• What is a String made of?
• How to declare a method with a variable number of arguments?
• What is the difference between interface and abstract class?
• What if both implemented interfaces declare the same method?
• How do atomics work?
• What happens if the finally block throws an exception?
• What is a daemon thread and how to create one?
• Why are thread-local variables used?
• How to work with Shutdown Hooks
• How to write an immutable class?
• What is the difference between JDK and JRE?
• How to use regular expressions in java?
• Which classes are involved in connecting to a database?
• What is the purpose of the assert keyword?
• Features of the Matcher class
• What is the difference between JAR and WAR files?
• How Does Spring Framework Implement the Dependency Injection Pattern?
• How to use SPI?
• Where is the entry point of a Java application?
• What is the default scope of Spring beans?
• What is a functional interface?
• What is classpath?
• What is in the manifest file?
• What is the purpose of the super keyword?
• When to use WEB-INF and when to use META-INF?
• Can a static method be overridden?
• How to launch another program from a Java application?
• When are aware interfaces used in Spring?
• Describe the Lifecycle of a Spring Bean