Books

Learn HTML Learn CSS Learn Git Learn Javascript Learn PHP Learn python Learn Java

Exercises

HTML JavaScript Git CSS PHP

Courses Quizzes Snippets

Tools

General Tools

Password Generator
HTML Editor
HTML Encoder
Base 64
Code Diff
JSON Beautifier
CSS Beautifier
Markdown Convertor
Find the Closest Tailwind CSS Color
Phrase encrypt / decrypt
Browser Feature Detection
Number convertor
JTW Decoder

CSS Maker

CSS Maker
CSS Maker text shadow
CSS Maker Text Rotation
CSS Maker Out Line
CSS Maker RGB Shadow
CSS Maker Transform
CSS Maker Font Face

Color Tools

Color Picker
Colors CMYK
Colors HWB
Colors HSL
Color Hex
Color mixer
Color Converter
Colors RGB
Color Contrast Analyzer
Color Gradient

String Tools

String Length Calculator
MD5 Hash Generator
Sha256 Hash Generator
String Reverse
URL Encoder
URL Decoder
Base 64 Encoder
Base 64 Decoder
Extra Spaces Remover
String to Lowercase
String to Uppercase
Word Count Calculator
Empty Lines Remover
HTML Tags Remover
Binary to Hex
Hex to Binary
Rot13 Transform on a String
String to Binary
Duplicate Lines Remover

Books
How To

Java Basics

1/25 What does the 'transient' keyword signify in a Java class?
- The variable can be serialized
- The variable is thread-safe
- The variable cannot be serialized
- The variable is volatile
2/25 Which collection class in Java is synchronized?
- ArrayList
- LinkedList
- Vector
- HashSet
3/25 What is the primary purpose of the 'super' keyword in Java?
- To call a method of the parent class
- To declare variables
- To create a new instance of the parent class
- To override a method in the child class
4/25 What is the default value of a static variable in Java?
- 0 or null, depending on the type
- 1
- undefined
- It does not have a default value
5/25 What is the use of the 'final' keyword in Java?
- To finalize object creation
- To create a constant variable or method
- To indicate the final class in a hierarchy
- To finalize variable assignments
6/25 What is the default size of a 'HashSet' in Java?
- 16
- 10
- 12
- 32
7/25 In Java, what does the 'volatile' keyword do to a variable?
- It ensures the variable is synchronized across threads
- It makes the variable immutable
- It increases the variable's access speed
- It makes the variable transient
8/25 How do you handle exceptions in Java?
- Using try-catch blocks
- By using the 'throws' keyword
- By using the 'extends' keyword
- By declaring them as static
9/25 Which of these is an immutable class in Java?
- java.lang.StringBuilder
- java.lang.String
- java.lang.StringBuffer
- java.util.ArrayList
10/25 What is 'autoboxing' in Java?
- Automatically converting a primitive type into its corresponding wrapper class
- The process of optimizing code automatically
- Creating an automatic backup of the code
- A feature for automatic memory management
11/25 What does the 'abstract' keyword signify in a Java class?
- The class can't be instantiated directly
- The class is fully implemented
- The class is optimized for performance
- The class can be instantiated multiple times
12/25 Which method must be implemented in a class that implements the java.util.Comparator interface?
- compare()
- compareTo()
- equals()
- hashCode()
13/25 What is the concept of 'overloading' in Java?
- Assigning extra resources to a Java application
- Creating multiple methods in a class with the same name but different parameters
- Increasing the memory allocation to a Java program
- Replacing a method in a subclass with a method from the superclass
14/25 In Java, which method you must override to use an object as a key in a HashMap?
- hashKey()
- mapKey()
- equals() and hashCode()
- getKey()
15/25 In Java, what is the effect of assigning a 'null' value to a reference variable?
- The reference variable is deleted
- It causes a compile-time error
- The reference variable points to no object
- It automatically initializes the object
16/25 What is 'garbage collection' in Java?
- A process of deallocating memory by manually deleting objects
- A process of automatically freeing memory occupied by objects that are no longer in use
- A tool for optimizing Java code
- A method for storing unused objects
17/25 What does the 'throws' keyword do in Java?
- Automatically handles an exception
- Declares an exception which might be thrown
- Stops the propagation of an exception
- Increases the throw range of an exception
18/25 In Java, what is 'reflection' used for?
- To modify the behavior of a program at runtime
- To duplicate objects
- To analyze the performance of applications
- To convert primitive types into objects
19/25 What does the 'final' keyword indicate when applied to a method in Java?
- The method can be overridden in a subclass
- The method cannot be overridden in a subclass
- The method will return a final value
- The method will be executed at the end of the program
20/25 How can you achieve thread safety in Java?
- By using synchronized blocks or methods
- By avoiding the use of multiple threads
- By using the 'volatile' keyword
- By making all methods and variables private
21/25 What is 'JDBC' in Java?
- Java Database Connectivity, a standard API for database access
- Java Data Binding Code, a framework for binding data to UI elements
- Just-in-time Database Compiler, a tool for database optimization
- Java Deployment and Compilation, a deployment tool
22/25 In Java, what does the 'transient' keyword do when applied to a class field?
- Makes the field non-serializable
- Marks the field as temporary and not part of the class's persistent state
- Indicates that the field value can change rapidly
- Makes the field volatile
23/25 In Java, what is the purpose of the 'enum' keyword?
- To define a new exception type
- To declare a collection of constants
- To create an enumeration of values for iteration
- To optimize memory usage in large applications
24/25 In Java, what is the default value of a boolean variable in a class?
- true
- false
- null
- 0
25/25 What does the 'static' keyword signify when applied to a block of code in Java?
- The code block is related to the static members of the class
- The code block cannot be modified
- The code block is executed when the JVM loads the class
- The code block is executed immediately after the class is instantiated
To get the result of the quiz, please provide your email address (optional)..

It seems you haven't answered any questions yet. Please provide your answers to proceed.

Quizzes
Snippets
Our Books
- Learn HTML
- Learn CSS
- Learn Git
- Learn Javascript
- Learn PHP
- Learn python
- Learn Java
- Exercises
- HTML
- JavaScript
- Git
- CSS
- PHP
Our Tools

About Us
Privacy Policy for W3Docs

Follow Us

Company © W3docs. All rights reserved.