Join David Gassner for an in-depth discussion in this video Using abstract classes and methods, part of Java Essential Training.
- When designing an object-oriented,…contract-based programming architecture,…you can frequently choose…between using interfaces and abstract classes.…An abstract class is abstract…because you add the abstract keyword…and then it can contain a mixture…of fully implemented methods and abstract methods.…An abstract method is just like a method in an interface.…It doesn't have an implementation.…It just indicates the method signature…and then any subclasses of an abstract method…must implement that method.…
In this project, the Olive class…is the superclass for two subclasses,…Ligurian and Kalamata.…I'm going to change this class and make it abstract…by adding the abstract keyword after public…and before the keyword class.…Now that doesn't change any behavior on its own.…I'll run the application…and show that everything still works.…But now, I'll declare an abstract method…as part of this class.…I'll place this new method down here…after all the setters and getters,…but before toString.…
I'll set it as public…and then put in the keyword abstract.…
Author
David Gassner
Released
7/24/2015- Understanding the history and principles of Java
- Installing Java, IntelliJ IDEA, and BlueJ
- Creating a Java project
- Working with variables, values, and expressions
- Working with object data types
- Building, comparing, and parsing strings
- Debugging and exception handling
- Creating loops and reusable code
- Passing arguments by reference or value
- Using simple and complex arrays
- Creating custom classes
- Understanding inheritance and polymorphism
- Managing files with Java libraries
- Documenting code with Javadoc
- Packaging classes in JAR files
Skill Level Beginner
Duration
Views
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Introduction
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Welcome59s
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Is this course for you?3m 22s
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Using the exercise files5m 5s
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1. What Is Java?
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The history of Java5m 57s
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Java syntax and compilation5m 26s
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2. Installing the Software
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Installing Java on Windows3m 49s
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Installing Java on OS X2m 50s
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Installing BlueJ1m 52s
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3. Getting Started
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Hello World5m 44s
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4. Working with Variables
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Converting numeric values5m 37s
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Using Java operators6m 11s
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5. Working with Objects
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Using the String class5m 5s
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Comparing string values5m 51s
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Parsing string values3m 13s
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Working with dates and times8m 35s
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6. Exception Handling and Debugging
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Debugging with IntelliJ IDEA5m 18s
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Throwing custom exceptions3m 19s
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7. Managing Program Flow
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Using the switch statement4m 51s
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Creating looping code blocks5m 23s
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8. Using Data Collections
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Using simple arrays6m 32s
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Using two-dimensional arrays4m 17s
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9. Creating Custom Classes
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Understanding encapsulation7m 19s
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Using constructor methods4m 56s
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10. Working with Inheritance
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11. Using Common Java Libraries
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12. Preparing a Java Application for Deployment
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Conclusion
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Next steps1m 37s
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Video: Using abstract classes and methods