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Advanced Java Programming

The substitution principle in Java

From the course: Advanced Java Programming

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  • Course details

    Want to get more out of the Java language and platform? In this platform- and framework-neutral course, instructor Bethan Palmer digs into some of the language’s more advanced features, helping you expand your programming skills as she equips you with techniques you can use when building applications anywhere Java is used: in web, mobile, and desktop applications. Bethan covers a variety of topics, including generics, working with the Collections Framework, and functional programming. Plus, learn about I/O in Java, working with files and directories, and structuring applications using the modular system available in Java.

    Instructor

    • Click here to view Bethan Palmer’s instructor page

      Bethan Palmer

      Software Developer and Java Champion

      Bethan Palmer is a developer who loves technology and has a master's degree in computer science.

      For her day job, Bethan is a Java programmer and the product manager for a Java PDF library at IDRsolutions. She gets to spend a lot of time writing and refactoring code, as well as deciding on product strategy and road maps.

      She also spends much of her time attending conferences and is a regular speaker at Oracle Code One and NetBeans Days. She manages and writes articles about Java, technology, the books she's reading, and conferences she's attending on the Java PDF blog.

    Skills covered in this course

    For each course you will get

    • Exercise files and quizzes
    • Certificate of completion from LinkedIn
    • Offline and audio-only options
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  • Learn advanced Java programming

    - [Instructor] The substitution principle, which is also known as the Liskov Substitution Principle is an important concept in object-oriented programming because it allows you to write maintainable and reusable code. The name makes it sound like it's going to be a complicated concept, but it is actually very simple. It just means that if you have a variable of a given type you can assign it to a value that is a subtype of that type. In this example I have a simple class called Building which simply overwrites the toString method to print out that it is a Building. I then have another simple class called Office which extends the Building class and overrides the toString method again to print out that this is an office. I then have a Main class. In the main method I have created a building variable and assigned it to a new Building object. I have then created a second building object. But instead of assigning it to a building, I have assigned it to a new Office object. In this class I…

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