a)
Abstract class:
An abstract class is a class which may or may not include abstract methods and cannot be instantiated but rather can be sub classed.
Legal abstract class:
The conditions for a class to be considered as legal abstract class are mentioned below:
- If a class includes abstract methods, then the class must be declared as abstract.
- The abstract method that is declared within the abstract class must be declared without braces and followed by a semicolon.
Interface:
Interface is a reference type in Java, which contains a collection of abstract methods.
An interface needs to the follow certain conditions such as:
- One cannot instantiate an interface.
- Interfaces do not contain any constructors.
- All methods present in the interface are abstracts.
- An interface does not contain any instance field.
- An interface cannot be extended by a class.
b)
Abstract class:
An abstract class is a class which may or may not include abstract methods and cannot be instantiated but rather can be sub classed.
Legal abstract class:
The conditions for a class to be considered as legal abstract class are mentioned below:
- If a class includes abstract methods, then the class must be declared as abstract.
- The abstract method that is declared within the abstract class must be declared without braces and followed by a semicolon.
Interface:
Interface is a reference type in Java, which contains a collection of abstract methods.
An interface needs to the follow certain conditions such as:
- One cannot instantiate an interface.
- Interfaces do not contain any constructors.
- All methods present in the interface are abstracts.
- An interface does not contain any instance field.
- An interface cannot be extended by a class.
c)
Abstract class:
An abstract class is a class which may or may not include abstract methods and cannot be instantiated but rather can be sub classed.
Legal abstract class:
The conditions for a class to be considered as legal abstract class are mentioned below:
- If a class includes abstract methods, then the class must be declared as abstract.
- The abstract method that is declared within the abstract class must be declared without braces and followed by a semicolon.
Interface:
Interface is a reference type in Java, which contains a collection of abstract methods.
An interface needs to the follow certain conditions such as:
- One cannot instantiate an interface.
- Interfaces do not contain any constructors.
- All methods present in the interface are abstracts.
- An interface does not contain any instance field.
- An interface cannot be extended by a class.
d)
Abstract class:
An abstract class is a class which may or may not include abstract methods and cannot be instantiated but rather can be sub classed.
Legal abstract class:
The conditions for a class to be considered as legal abstract class are mentioned below:
- If a class includes abstract methods, then the class must be declared as abstract.
- The abstract method that is declared within the abstract class must be declared without braces and followed by a semicolon.
Interface:
Interface is a reference type in Java, which contains a collection of abstract methods.
An interface needs to the follow certain conditions such as:
- One cannot instantiate an interface.
- Interfaces do not contain any constructors.
- All methods present in the interface are abstracts.
- An interface does not contain any instance field.
- An interface cannot be extended by a class.
e)
Abstract class:
An abstract class is a class which may or may not include abstract methods and cannot be instantiated but rather can be sub classed.
Legal abstract class:
The conditions for a class to be considered as legal abstract class are mentioned below:
- If a class includes abstract methods, then the class must be declared as abstract.
- The abstract method that is declared within the abstract class must be declared without braces and followed by a semicolon.
Interface:
Interface is a reference type in Java, which contains a collection of abstract methods.
An interface needs to the follow certain conditions such as:
- One cannot instantiate an interface.
- Interfaces do not contain any constructors.
- All methods present in the interface are abstracts.
- An interface does not contain any instance field.
- An interface cannot be extended by a class.
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Introduction to Java Programming and Data Structures, Comprehensive Version (11th Edition)
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