Join Peggy Fisher for an in-depth discussion in this video Establishing abstract classes, part of Java Essential Training for Students.
- Moving on to Abstract Classes.…When defining an abstract class…you must include the keyword Abstract…in the class header.…Such as, Public, Abstract, Class, Shape.…The class may or may not include abstract methods.…It's important to understand you cannot instantiate…an object that is of the type of the abstract class.…Although abstract classes cannot be instantiated,…they can have subclasses.…And any abstract methods inside the abstract class…are declared without an implementation…and only the method header.…
So what happens when a class…inherits from an abstract class?…The subclass must provide the implementation…for all the abstract methods that are in the parent class.…If it does not, it must be declared as abstract also.…Abstract classes are similar to interfaces.…Once again, you cannot instantiate an interface,…and an interface may contain a mix of methods…that are with or without code.…When we worked with the geometry class earlier…and we had a shape class, it was an abstract class.…
Lets go back to that.…
- Getting started with parsing
- Reviewing data types
- Using decisions
- Creating user-defined methods
- Command-line debugging
- Exploring the Java API
- Creating and instantiating classes
- Working with interfaces
- Storing items with arrays
Skill Level Intermediate
Q: How can I make my debugger function like the author’s?
<div>A: When you are debugging your program in NetBeans, if you do not see the new contextual items on the menu bar for stepping into your code, check to see if the source file is accidentally deselected.</div><div> </div><div>Highlight the program you want to debug in your projects folder. In the menu bar, choose Windows > Debugging > Sources. A new window will appear with the file path name. If the checkbox is not selected, click the box to select this file.</div><div> </div><div>Now you can go back to your program and rerun the debug operation on your code.</div>
1. Command Level Programming
2. Basics Review
4. Java API
5. Simulations and Algorithm Analysis
6. Classes and Objects
7. More on Classes
8. Data Structures
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