From the course: Java SE 11 Developer (1Z0-819) Cert Prep

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Subclass declaration

Subclass declaration - Java Tutorial

From the course: Java SE 11 Developer (1Z0-819) Cert Prep

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Subclass declaration

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- Now it's time to investigate Subclass Declarations. Subclass declaration has a syntax which starts with a regular class declaration intro, followed by the keyword extends and a name of the parent class. Then optionally will have implements clause to follow. The extends keyword is followed by the parent class name and only one immediate parent class is ever permitted. Multiple parents do exist, but they are a chain of ancestors, parent, grandparent, and so forth. If the extends clause is emitted, the parent is implicitly Java.Lang.Object. If an implements clause is used, the extends clause must come first, if it's there too. Subclassing can be controlled. A class that is marked final cannot be sub classed. A class that has only private constructors can be sub classed only by nested or inner classes. The point here is that a subclass must be able to initialize its parent elements and must therefore have access to the parent class constructor. Methods in a subclass that have the same…

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