Java Tutorial
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Java Built-in Classes
Java File Handling
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Java Error & Exceptions
- Java - Exceptions
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Java Multithreading
- Java - Multithreading
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- Java - Creating a Thread
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Java Synchronization
- Java - Synchronization
- Java - Block Synchronization
- Java - Static Synchronization
- Java - Inter-thread Communication
- Java - Thread Deadlock
- Java - Interrupting a Thread
- Java - Thread Control
- Java - Reentrant Monitor
Java Networking
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Java Collections
Java List Interface
Java Queue Interface
Java Map Interface
- Java - Map Interface
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Java Set Interface
- Java - Set Interface
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Java Data Structures
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- Java - Dictionary
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Java Collections Algorithms
Advanced Java
- Java - Command-Line Arguments
- Java - Lambda Expressions
- Java - Sending Email
- Java - Applet Basics
- Java - Javadoc Comments
- Java - Autoboxing and Unboxing
- Java - File Mismatch Method
- Java - REPL (JShell)
- Java - Multi-Release Jar Files
- Java - Private Interface Methods
- Java - Inner Class Diamond Operator
- Java - Multiresolution Image API
- Java - Collection Factory Methods
- Java - Module System
- Java - Nashorn JavaScript
- Java - Optional Class
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- Java - Base64 Encode Decode
- Java - Switch Expressions
- Java - Teeing Collectors
- Java - Microbenchmark
- Java - Text Blocks
- Java - Null Pointer Exception
- Java - Packaging Tools
- Java - Sealed Classes
- Java - Record Classes
- Java - Hidden Classes
- Java - Compact Number Formatting
Java Miscellaneous
- Java - Recursion
- Java - Regular Expressions
- Java - Serialization
- Java - Strings
- Java - Process API Improvements
- Java - Stream API Improvements
- Java - Enhanced @Deprecated Annotation
- Java - CompletableFuture API Improvements
- Java - Array Methods
- Java - Streams
- Java - Datetime Api
- Java 8 - New Features
- Java 9 - New Features
Java APIs & Frameworks
Java Useful Resources
Java Online Quiz
Following quiz provides Multiple Choice Questions (MCQs) related to Core Java. You will have to read all the given answers and click over the correct answer. If you are not sure about the answer then you can check the answer using Show Answer button. You can use Next Quiz button to check new set of questions in the quiz.
Q 1 - What of the following is the default value of an instance variable?
Answer : C
Explaination
Instance variables are assigned default values based on their types. For example, int variable is assigned 0 and an object type variable is assigned null as default value.
Answer : B
Explaination
The short data type is represented by 16-bit signed two's complement integer.
Minimum value: -32,768
Maximum value: 32,767
Answer : A
Explaination
Byte variable has default value of 0 if defined as an instance/static variable.
Answer : C
Explaination
Object variable has default value of null if defined as an instance/static variable.
Answer : B
Explaination
Inheritance represets IS-A relationship providing code reusablity . Consider the following statement: Circle is a Shape. Here Shape is super class and Circle is a child class extends the super class Shape.
Q 6 - What is JRE?
A - JRE is a java based GUI application.
B - JRE is an application development framework.
C - JRE is an implementation of the Java Virtual Machine which executes Java programs.
Answer : C
Explaination
Java Runtime Environment is an implementation of the Java Virtual Machine which executes Java programs. It provides the minimum requirements for executing a Java application.
Q 7 - What is composition?
A - Composition is a data structure.
B - Composition is a way to create an object.
C - Holding the reference of the other class within some other class is known as composition.
Answer : C
Explaination
Holding the reference of the other class within some other class is known as composition. It represents a HAS-A relationship. For example, a Student has a Pen. Here Student class has Pen as its instance variable.
Q 8 - Which is the way in which a thread can enter the waiting state?
A - Invoke its sleep() method.
B - invoke object's wait method.
Answer : D
Explaination
A thread can enter the waiting state by invoking its sleep() method, by blocking on IO, by unsuccessfully attempting to acquire an object's lock, or by invoking an object's wait() method. It can also enter the waiting state by invoking its (deprecated) suspend() method.
Q 9 - What is runtime polymorphism?
Answer : A
Explaination
Runtime polymorphism or dynamic method dispatch is a process in which a call to an overridden method is resolved at runtime rather than at compile-time. In this process, an overridden method is called through the reference variable of a superclass.
Answer : A
Explaination
Postfix operators i.e () [] . is at the highest precedence.
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