Java Core in Practice: 120+ Exercises and Quizzes for 2025 from Udemy

What's inside

Learning objectives

Java core
Java development kit (jdk) setup
Basic java program execution
Integrated development environment (ide) understanding
Primitive data types usage
Variable declaration and initialization
Type casting
Primitive and non-primitive data type differentiation
Array and string declaration
Variable naming conventions
Variable scope
Console output
Console input using the scanner class
Arithmetic operators usage
Comparison and logical operators usage
Operator precedence understanding
If-else statement usage
Switch statement usage
Loop usage (for, while, do-while)
Loop control (break, continue)
Method definition and invocation
Method overloading
Recursion in methods
Array manipulation
String immutability understanding
String concatenation
String comparison
String formatting
String pool concept

Class and object creation
Constructor usage
Encapsulation with getters and setters
Inheritance implementation
Method overriding
Use of the super keyword
Polymorphism in java
Method overloading and overriding differentiation
Abstract classes and interfaces usage
Solid principles application
Exception handling with try-catch blocks
Checked and unchecked exceptions differentiation
Custom exception creation
List, set, and queue usage
Map manipulation
Iterator usage
Enumerations
Generic class and method creation
Input/output stream usage
Object serialization and deserialization
Thread management
Synchronization for thread safety
Executor framework usage
Fork/join framework usage
Thread pooling
Atomic variables for thread safety
Inter-thread communication with wait-notify
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Java core
Java development kit (jdk) setup
Basic java program execution
Integrated development environment (ide) understanding
Primitive data types usage
Variable declaration and initialization
Type casting
Primitive and non-primitive data type differentiation
Array and string declaration
Variable naming conventions
Variable scope
Console output
Console input using the scanner class
Arithmetic operators usage
Comparison and logical operators usage
Operator precedence understanding
If-else statement usage
Switch statement usage
Loop usage (for, while, do-while)
Loop control (break, continue)
Method definition and invocation
Method overloading
Recursion in methods
Array manipulation
String immutability understanding
String concatenation
String comparison
String formatting
String pool concept
Class and object creation
Constructor usage
Encapsulation with getters and setters
Inheritance implementation
Method overriding
Use of the super keyword
Polymorphism in java
Method overloading and overriding differentiation
Abstract classes and interfaces usage
Solid principles application
Exception handling with try-catch blocks
Checked and unchecked exceptions differentiation
Custom exception creation
List, set, and queue usage
Map manipulation
Iterator usage
Enumerations
Generic class and method creation
Input/output stream usage
Object serialization and deserialization
Thread management
Synchronization for thread safety
Executor framework usage
Fork/join framework usage
Thread pooling
Atomic variables for thread safety
Inter-thread communication with wait-notify
Show more
Show less

Syllabus

The learning objective of this section is to teach students how to set up and configure their Java development environment, create and run basic Java programs, and troubleshoot common setup issues.

Overview of course and what will be covered
Goals and objectives of the course
Prerequisites and recommended background knowledge
Course materials and resources
Introduction to the Java programming language and its importance in the industry

Installing the Java Development Kit (JDK)
Configuring the JDK and setting the JAVA_HOME environment variable

Installing the Java Development Kit (JDK)

Common errors that may occur while setting up the development environment
How to troubleshoot and resolve these errors

Creating a new Java file
Understanding the structure of a Java program and the role of the main method
Writing code for a simple console program
Compiling .java files to bytecode
Running the program from the command line

Definition and purpose of IDEs
Comparison of IDEs to text editors
Importance of using an IDE in Java development
Popular IDEs for Java development

Downloading and installing IntelliJ IDEA
Creating a new project in the IntelliJ IDEA
Writing and executing a simple Java program

Explanation of what data types and variables are
Importance of understanding data types and variables in programming

Explanation of primitive data types and their uses
Integer data types (byte, short, int, long)
Floating-point data types (float, double)
Character and boolean data types
Demonstration of how to declare and initialize variables of different primitive data types
Casting

Explanation of non-primitive data types (String, arrays, classes)
Comparison of primitive and non-primitive data types
Demonstration of how to declare and initialize variables of non-primitive data types

This quiz covers the fundamental concepts of non-primitive data types in Java, focusing on Strings, arrays, and classes, as well as differences between primitive and non-primitive types.

Explanation of variable naming conventions in Java
Explanation of variable scope
Demonstration of how variable scope affects program behavior

This quiz covers the key concepts of variable naming conventions and scope in Java, ensuring a better understanding of best practices for variable names and the different scopes that affect variable accessibility.

Using the System.out.print() and System.out.println() methods to write to the console
Examples of writing different data types to the console
Formatting output with printf() method

This quiz covers the essential concepts of writing to the console in Java, focusing on the use of System.out.print(), System.out.println(), and System.out.printf() methods.

Using the Scanner class to read input from the console
Examples of reading different data types from the console

This quiz covers the essential concepts of reading input from the console using the Scanner class in Java, focusing on correct usage and exception handling.

Arithmetic operators (e.g. +, -, *, /)
Comparison operators (e.g. ==, !=, >, <)
Logical operators (e.g. &&, ||, !)
Assignment operators (e.g. =, +=, -=)

This quiz covers the essential concepts of operators in Java, focusing on arithmetic, comparison, logical, and assignment operators.

Understanding operator precedence in expressions
Examples of how operator precedence affects the outcome of an expression

This quiz covers the essential concepts of operator precedence in Java, ensuring a better understanding of how different operators are prioritized in expressions.

Common mistakes when using operators and expressions
Best practices for writing clear and efficient code using operators and expressions

This quiz covers common pitfalls and best practices in Java programming, focusing on correct usage of operators, proper string declaration, order of operations, and improving code readability and maintainability.

Syntax and usage of if-else statements
Example of if-else statements in Java code
Nesting of if-else statements

This quiz covers the essential concepts of if-else statements in Java, focusing on correct syntax, nesting, and if-else ladder usage.

Syntax and usage of switch statements
Example of switch statements in Java code
Differences between switch and if-else statements

This quiz covers the essential concepts of switch statements in Java, focusing on correct syntax, usage, and differences from if-else statements.

Types of loops in Java (for, while, do-while)
Syntax and usage of each loop type
Examples of loops in Java code
Usage of break and continue
Tips for efficient looping

This quiz covers the essential concepts of loops in Java, focusing on for, while, and do-while loops, as well as the break and continue statements.

Definition of a method in Java
Syntax of declaring a method in Java
Types of methods (void, non-void)
Defining parameters for a method
Return types of methods
Method overloading
Method invocation
Parameter passing mechanism in Java
Recursive methods
Varargs in the methods

This quiz covers the essential concepts of methods in Java, focusing on declaration, invocation, overloading, recursion, and varargs.

Creating and initializing arrays
Accessing and modifying array elements
Iterating through arrays
Common methods for arrays (length, sort, etc.)
Multidimensional arrays

This quiz covers the essential concepts of arrays in Java, focusing on declaration, initialization, accessing elements, modifying elements, common methods, and multidimensional arrays.

Overview of the concept of strings in Java
Differences between string literals and string objects

This quiz covers the essential concepts of strings in Java, focusing on creation, comparison, and important methods such as length() and equals().

String methods such as length(), charAt(), indexOf()
Immutability of strings and its implications

This quiz covers the essential concepts of string objects in Java, focusing on common methods, immutability, and string interning.

Using the + operator for concatenation
Using the StringBuilder and StringBuffer classes for concatenation

This quiz covers the essential concepts of string concatenation in Java, focusing on the + operator, StringBuilder, and StringBuffer classes.

Compare strings using the equals() and equalsIgnoreCase() methods
Compare strings using the == operator and the compareTo() method

This quiz covers the essential concepts of string comparison in Java, focusing on the equals(), equalsIgnoreCase(), ==, and compareTo() methods.

Syntax and usage of the String.format() method
Examples of formatting strings using placeholders and format specifiers

This quiz covers the essential concepts of string formatting using the String.format() method in Java, focusing on format specifiers and their usage.

Understanding of string pool concept
How string pool works in Java

This quiz covers the essential concepts of the string pool in Java, focusing on string creation, comparison, and the use of the intern() method.

Definition and explanation of a class in Java
Creating a class and understanding its structure
Fields
Methods

This quiz covers the essential concepts of classes in Java, focusing on class definitions, fields, methods, and initialization techniques.

Definition and explanation of an object in Java
Creating an object from a class
Understanding the relationship between classes and objects
Using the dot operator to access object methods and variables
Understanding the difference between an object's reference and its value

This quiz covers the essential concepts of objects in Java, focusing on object creation, the relationship between classes and objects, constructors, and accessing object fields.

'static' keyword
Access modifiers
Initialization blocks
Nested classes
Getters and setters

This quiz covers advanced concepts of classes and objects in Java, including the use of the static keyword, access modifiers, initialization blocks, nested classes, and getters and setters.

Definition and explanation of constructors in Java
Types of constructors: default and parameterized
'this' keyword
How constructors are used when creating objects

This quiz covers the essential concepts of constructors in Java, focusing on their definition, usage, types, overloading, and chaining.

Overview of interfaces in Java
Defining an interface
Implementing an interface
Extending an interface
Default and static methods in interfaces

This quiz covers the essential concepts of interfaces in Java, focusing on their definition, implementation, multiple inheritance, default methods, and static methods.

Overview of abstract classes in Java
Defining an abstract class
Extending an abstract class
Abstract methods and concrete methods
Abstract classes vs concrete classes

This quiz covers the essential concepts of abstract classes in Java, focusing on their definition, usage, and the differences between abstract and concrete methods.

Differences between interfaces and abstract classes
When to use interfaces and when to use abstract classes
Extending an abstract class and implementing an interface
Differences between "implements" and "extends"

This quiz covers the essential concepts of combining interfaces and abstract classes in Java, focusing on their differences, usage, and the implementation of both in a single class.

Definition and explanation of inheritance in OOP
Examples of inheritance in real-world scenarios
How inheritance allows for code reuse and organization
Extending classes in Java
Understanding the relationship between parent and child classes
Overriding methods in child classes
Understanding the use of the "super" keyword
Understanding the "is-a" relationship in inheritance

This quiz covers the essential concepts of inheritance in Java, focusing on class hierarchies, method overriding, the super keyword, and access control.

Definition and explanation of polymorphism in OOP
How polymorphism allows for flexibility and dynamic behavior in code
Understanding the difference between overloading and overriding methods
Examples of polymorphism in use, such as with the "instanceof" operator

This quiz covers the essential concepts of polymorphism in Java, focusing on method overloading, method overriding, the instanceof operator, and dynamic dispatch.

Traffic lights

Read about what's good

what should give you pause

and possible dealbreakers

Provides a solid foundation in Java programming, making it suitable for individuals with no prior coding experience and those looking to switch careers into the tech industry

Includes over 120 exercises and quizzes, offering ample opportunities for hands-on practice and knowledge assessment, which is crucial for mastering Java programming concepts

Covers essential Java concepts such as data types, control flow, methods, arrays, strings, and object-oriented programming principles, providing a comprehensive understanding of the Java language

Explores advanced topics like exception handling, collections, generics, input/output streams, multithreading, and synchronization, enabling learners to develop robust and efficient Java applications

Features real-life examples and practical coding exercises, allowing learners to apply their knowledge to solve real-world problems and gain practical experience in Java development

Requires learners to set up and configure their Java development environment, which may pose a challenge for complete beginners who are not familiar with software installation and configuration processes

Reviews summary

Practical java core with extensive practice

According to learners, this course offers a very comprehensive and practical approach to Java Core. Students praise the instructor's clear explanations and the extensive number of hands-on exercises and quizzes, which are described as extremely helpful for solidifying understanding and building confidence. The course structure is generally found to be easy to follow, building concepts step-by-step. While some found the pace suitable for beginners and those reviewing fundamentals, a few noted that it requires dedication and practice to fully grasp the material, especially the more advanced topics like concurrency. The emphasis on practice makes it particularly suitable for those aiming for job-ready skills.

Demands significant practice and focus.

"The course has more than 120+ exercises and quizzes. Which means a lot of dedication and time commitment is required to complete them."

"While the explanations are clear, mastering the concepts definitely requires consistent practice."

"To get the most out of this course, be prepared to spend ample time on the coding exercises."

"It's not a passive course; you have to actively work through the problems."

Well-structured and good starting point.

"Whether you’re just starting, thinking about switching careers, or simply curious about coding... perfect for everyone"

"Even if you’ve never written a single line of code, this course will guide you step by step."

"I started as a complete beginner, and the step-by-step lessons made it easy to follow."

"It's a very accessible introduction to Java programming."

Focuses on practical skills needed for jobs.

"Instructor makes sure we understand why certain concepts are important for real-world applications."

"I feel more confident in applying my Java skills in a professional setting after taking this course."

"Great course if you are preparing for job interviews or just want to sharpen your Java fundamentals."

"The exercises feel relevant to tasks I might encounter in a Java developer role."

Provides a strong foundation in Java Core.

"This is an excellent course to start with or to revisit core java."

"The course gives me a very solid foundation on java core which is helping me a lot."

"I feel I have gained a strong understanding of the fundamental Java concepts."

"Really covers the essentials of Java needed to move on to more advanced topics."

Instructor explains concepts clearly and simply.

"Instructor explains everything in such a way that it is really understandable even if you are beginner."

"Andrii is an excellent and very clear instructor. Complex topics are broken down into easy to understand lectures."

"Lectures are clear and straight to the point, making learning very effective for me."

"I appreciate how well the concepts are explained throughout the lessons."

"The way the instructor explains the concepts made them easy to grasp."

Includes many exercises, quizzes, and coding tasks.

"There are many exercises to solidify the concepts. The best way to learn is by doing. This course provides that."

"This course has a very comprehensive and large amount of exercises and quizzes. It has allowed me to gain a solid understanding of Core Java."

"Practicing coding with 120+ exercises and quizzes mentioned in the title is extremely helpful."

"I liked the amount of hands-on coding opportunities the course provides."

"The exercises really helped reinforce what was taught in the lectures."

Activities

Be better prepared before your course. Deepen your understanding during and after it. Supplement your coursework and achieve mastery of the topics covered in Java Core in Practice: 120+ Exercises and Quizzes for 2025 with these activities:

Review Basic Programming Concepts

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Reinforce fundamental programming concepts like variables, loops, and conditional statements to prepare for Java-specific syntax and paradigms.

Browse courses on Programming

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Review notes from any previous programming courses or tutorials.
Complete online quizzes or practice exercises on basic programming concepts.
Write simple programs in any language to refresh your understanding of core concepts.

Review 'Head First Java'

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Solidify understanding of core Java concepts with a beginner-friendly book that uses visual aids and real-world examples.

View Head First Java: A Brain-Friendly Guide on Amazon

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Read the first few chapters covering basic Java syntax and object-oriented concepts.
Complete the exercises and quizzes at the end of each chapter.
Try to relate the concepts learned in the book to the course syllabus.

CodingBat Java Practice

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Sharpen coding skills by working through targeted Java exercises on CodingBat, focusing on topics covered in the current week's lessons.

Browse courses on Java

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Visit the CodingBat website and select the Java section.
Choose exercises related to the current week's topics (e.g., loops, strings, arrays).
Write and test your code for each exercise, aiming for correct solutions.

Five other activities

Expand to see all activities and additional details

Show all eight activities

Pair Programming Session

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Improve problem-solving skills and understanding of Java concepts by collaborating with a peer on coding exercises.

Browse courses on Pair Programming

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Find a classmate or fellow student to pair program with.
Choose a coding exercise or problem from the course materials or online resources.
Take turns writing and reviewing code, discussing solutions and approaches.

Create a Java Cheat Sheet

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Consolidate knowledge and improve retention by creating a concise cheat sheet summarizing key Java syntax, concepts, and best practices.

Browse courses on Java

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Review the course materials and identify the most important concepts and syntax.
Organize the information into a clear and concise cheat sheet format.
Include examples and explanations for each concept.

Build a Simple Calculator

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Apply learned Java concepts by building a simple calculator application that performs basic arithmetic operations.

Browse courses on Calculator

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Plan the calculator's functionality and user interface.
Write the Java code to implement the calculator's logic.
Test the calculator thoroughly to ensure it works correctly.

Review 'Effective Java'

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Deepen understanding of Java best practices and design principles with a classic guide from a renowned Java expert.

View Effective Java (3rd Edition) on Amazon

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Read chapters related to topics covered in the course, such as object-oriented design and concurrency.
Reflect on how the advice in the book applies to your own Java projects.
Experiment with implementing the recommended best practices in your code.

Contribute to a Java Open Source Project

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Gain real-world experience and deepen Java skills by contributing to an open-source project, learning about code collaboration and software development workflows.

Browse courses on Open Source

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Find a Java open-source project that interests you on platforms like GitHub.
Review the project's documentation and contribution guidelines.
Identify a bug or feature to work on and submit a pull request with your changes.

Career center

Learners who complete Java Core in Practice: 120+ Exercises and Quizzes for 2025 will develop knowledge and skills that may be useful to these careers:

Java Developer

A Java developer specializes in creating software using the Java programming language. This Java Core course is perfectly tailored for anyone looking to enter or advance in this role. The course provides a comprehensive exploration of Java, starting from the basics to advanced topics, including object-oriented programming, data structures, and multithreading. With the course's emphasis on hands-on coding exercises, quizzes, and access to all sample code, learners will gain practical experience and demonstrate the ability to write, debug, and maintain Java code effectively, making them a highly competitive candidate in the job market.

See salaries and explore the career path for Java Developer

Junior Programmer

A junior programmer is an entry-level role in software development, typically involving writing code and participating in project teams. This Java Core course directly helps aspiring junior programmers develop the essential skills and knowledge to excel at this role. The course covers fundamental topics like Java syntax, control structures, and object-oriented programming. Further, the course's emphasis on hands-on exercises and quizzes helps learners build a solid foundation. This course acts as an excellent starting point for anyone seeking to begin their career as a junior programmer.

See salaries and explore the career path for Junior Programmer

Software Developer

A software developer designs, codes, and tests software applications. This Java Core course is an excellent starting point for aspiring developers because it gives a thorough introduction to the Java programming language, covering essential topics such as data types, control flow, methods, and object-oriented programming principles. The course’s hands-on exercises and quizzes help build a strong foundation in practical coding skills. This approach not only teaches how to write Java but also how to think like a developer, applying knowledge to real-world problems and preparing students to build their own applications.

See salaries and explore the career path for Software Developer

Application Developer

An application developer builds and maintains software applications for computers and mobile devices. This Java Core course introduces the foundational concepts needed for this role, including how to set up a development environment and write, compile, and execute programs. The course’s focus on real-world examples and hands-on exercises makes the learning process both engaging and effective. The course material assists greatly, and can readily be applied to create the structure and logic required for applications, making it an ideal choice for those seeking a career as an application developer.

See salaries and explore the career path for Application Developer

Software Engineer

A software engineer applies engineering principles to the design, development, and maintenance of software systems. This Java Core course provides learners with the necessary building blocks for a successful career as a software engineer. The course rigorously covers the fundamentals of Java programming, including setting up the environment, using data structures, and mastering object-oriented principles. With its practical coding exercises and quizzes, the course assists in developing the skills needed for real-world problem-solving, enhancing one's capabilities for software engineering work.

See salaries and explore the career path for Software Engineer

Backend Developer

A backend developer focuses on the server-side logic, databases, and APIs that power applications. This Java Core course is very helpful for this role because it develops the knowledge and skills necessary for a backend developer. The course covers essential topics such as data types, control flow, and object-oriented programming in Java, which are crucial for building robust backend systems. The course's hands-on practice through coding exercises and quizzes means that students are well prepared to apply their skills in real-world backend development projects.

See salaries and explore the career path for Backend Developer

Full-Stack Developer

A full stack developer is proficient in both front-end and back-end development, capable of handling all aspects of a software application. This Java Core course may be useful for aspiring full stack developers, especially for the back-end portion. The course's curriculum covers crucial back-end languages including Java, along with key concepts such as object-oriented programming, data structures, and multithreading. Through practice exercises and quizzes, the course helps build a strong foundation in Java programming, which is essential given the versatility of Java in full stack development.

See salaries and explore the career path for Full-Stack Developer

Mobile App Developer

A mobile app developer creates applications for mobile devices, often using Java for Android app development. This Java Core course may be useful for this role because it covers the core concepts of Java, an important language in mobile app development. By studying how to set up a development environment, work with data types, control flow, and object-oriented programming, one can build a strong foundation for further specialization in mobile app development. The course’s emphasis on practical exercises also prepares learners for coding mobile applications.

See salaries and explore the career path for Mobile App Developer

Web Developer

A web developer creates and maintains websites, which may involve using Java for server-side development. This Java Core course may be useful for those interested in the back-end aspects of web development. This course covers essential programming concepts in Java, including object-oriented programming, data structures, and multithreading. This may assist learners who wish to use Java to develop server-side components of web applications. The course’s focus on practical exercises and real-world examples helps in building the skills and knowledge needed for this role.

See salaries and explore the career path for Web Developer

Game Developer

A game developer works on the design, coding, and testing of video games. This Java Core course may be useful for a game developer who wishes to use Java in game development. This course introduces core Java concepts, such as setting up the development environment, using data types, control flow, and object-oriented programming. Though game development requires additional specific knowledge, this foundational knowledge of Java programming can be helpful for a game developer.

See salaries and explore the career path for Game Developer

Data Scientist

A data scientist analyzes large datasets to extract meaningful insights and support business decisions. This role often requires a strong background in programming and statistics. This Java Core course may be useful for those who wish to use Java in the context of data science. Though data science typically relies more on languages like Python or R, a strong foundation in Java from this course may help in building data processing tools. The course covers fundamental programming concepts and may prove valuable to those who wish to add Java to their stack.

See salaries and explore the career path for Data Scientist

Data Analyst

A data analyst collects, processes, and analyzes data to identify patterns and trends. This Java Core course may be useful to those who want to use Java in the context of data analysis. Although data analytics roles often favor tools like Python and R, this course provides a foundational understanding of programming principles using Java. The course covers basic programming concepts like data types, control flow, and object-oriented programming. This foundation may be useful to data analysts looking to extend their skill set.

See salaries and explore the career path for Data Analyst

System Administrator

A system administrator manages and maintains computer systems and networks. This Java Core course may be useful for system administrators who wish to automate tasks or build simple tools with Java. Java is typically not a core language for sysadmin tasks, but a knowledge of programming can help with scripting and automation. The course covers basic programming in Java, which may be valuable to those who wish to extend their sysadmin toolkit.

See salaries and explore the career path for System Administrator

Quality Assurance Engineer

A quality assurance engineer ensures that software products meet the required standards and are free of defects. This Java Core course may be useful for quality assurance engineers who need to use Java to automate testing processes and create testing frameworks. The course’s rigorous coverage of Java concepts, combined with practical coding exercises, may equip engineers with a more detailed understanding of the underlying structure of software, facilitating more effective testing practices. The course is foundational, and additional specific training for testing will also be needed.

See salaries and explore the career path for Quality Assurance Engineer

Research Scientist

A research scientist conducts scientific studies and experiments, often involving data analysis and software development. This Java Core course may be useful for a research scientist who needs to use Java to develop tools or algorithms for data processing or simulation. The course provides a foundation in Java programming, covering essential topics such as data types, control flow, and object-oriented programming. Although research typically involves a variety of software, this course may provide a useful foundation in Java. Most research scientists hold a PhD.

See salaries and explore the career path for Research Scientist

Java Core in Practice

120+ Exercises and Quizzes for 2025

What's inside

Learning objectives

Syllabus

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Reviews summary

Practical java core with extensive practice

Activities

Career center

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