Java Interfaces Quiz

True (A)

zero

<p>Java does not support multiple inheritance.</p> Signup and view all the answers

<p>Interface = A blueprint or contract defining methods that implementing classes must provide. Implementation = The concrete definition of methods declared in an interface, provided by a class that implements it. Multiple Inheritance = A feature allowing a class to inherit from multiple parent classes, which is not directly supported in Java.</p> Signup and view all the answers

<p>To provide a blueprint for a class without providing implementation details (B)</p> Signup and view all the answers

<p>False (B)</p> Signup and view all the answers

<p>The ability of objects of different classes to respond to the same method call in different ways.</p> Signup and view all the answers

<p>decouple</p> Signup and view all the answers

<p>It can contain concrete methods with implementation (C)</p> Signup and view all the answers

<p>Interface = A blueprint that defines methods but does not provide implementation Abstract Method = A method declared in an interface that requires implementation by implementing classes Polymorphism = The ability of objects of different classes to respond to the same method call in different ways Decoupling = Reducing dependency between classes by using interfaces</p> Signup and view all the answers

<p>False (B)</p> Signup and view all the answers

<p>new class</p> Signup and view all the answers

<p>To specify sets of requirements for classes to implement. (A)</p> Signup and view all the answers

<p>Because they don't have a concrete implementation. They are designed to be implemented by classes that implement the interface.</p> Signup and view all the answers

<p>interface = A set of requirements for classes to implement abstract method = A method without implementation implements keyword = Used to indicate that a class implements an interface contract = A metaphor for the agreement between an interface and its implementing classes</p> Signup and view all the answers

<p>True (A)</p> Signup and view all the answers

<p>They can be accessed directly from the interface without needing to create an instance of the implementing class.</p> Signup and view all the answers

<p>implements</p> Signup and view all the answers

<p>True (A)</p> Signup and view all the answers

<p>Polymorphism</p> Signup and view all the answers

<p>cast</p> Signup and view all the answers

<p>Interfaces are slower and more limited than other languages. (C)</p> Signup and view all the answers

<p>The class must implement the interface.</p> Signup and view all the answers

<p>Direct instantiation of interface objects (A)</p> Signup and view all the answers

<p>True (A)</p> Signup and view all the answers

<p>object-oriented</p> Signup and view all the answers

<p>Enhancing code reusability by allowing a single method to be used for different types of objects. (B)</p> Signup and view all the answers

<p>The two main types of binding in polymorphism are <em>early binding</em> and <em>late binding</em>. Early binding, also known as <em>static binding</em>, occurs at compile time. This means the specific method to be called is determined before the program runs. On the other hand, late binding, also known as <em>dynamic binding</em>, occurs at runtime, meaning the specific method to be called is determined only when the program is executing.</p> Signup and view all the answers

<p>Polymorphism = The ability of a method to be used with different types of objects. Early Binding = Method resolution occurs at compile time Late Binding = Method resolution occurs at runtime Overloaded Methods = Multiple methods with the same name but different parameters Overridden Methods = Methods with the same name and parameters inherited from a parent class but with different implementations in the subclass</p> Signup and view all the answers

<p>Data compression (B)</p> Signup and view all the answers

<p>True (A)</p> Signup and view all the answers

<p>Placing the 'makeSound()' method within an interface allows for flexibility and extensibility. By using an interface, you can ensure that all classes implementing that interface will have the 'makeSound()' method, even if their implementations differ. This avoids the need to have multiple versions of the method in each class, promoting code reusability and maintainability.</p> Signup and view all the answers

<p>interface</p> Signup and view all the answers

<p>False (B)</p> Signup and view all the answers

<p>Flier fred = new Plane(); (B), Plane temp = (Plane) fred; (D)</p> Signup and view all the answers

<p>The cast converts the <code>Flier</code> object <code>fred</code> to a <code>Plane</code> object so it can be assigned to the <code>Plane</code> variable <code>temp</code>.</p> Signup and view all the answers

<p><code>Flier fred = new SkiJumper();</code> = Creating an object of a subclass <code>Athlete temp = (Athlete) fred;</code> = Casting to a superclass <code>SkiJumper temp = (SkiJumper) fred;</code> = Casting to a subclass <code>Plane temp = (Plane) fred;</code> = Potentially incorrect cast</p> Signup and view all the answers

<p>True (A)</p> Signup and view all the answers

<p>The <code>Comparable</code> interface defines a <code>compareTo</code> method. By implementing this method for a class, objects of that class can be compared to each other. This comparison is then used by sorting algorithms like <code>Collections.sort()</code> to order the objects.</p> Signup and view all the answers

<p>It allows objects to be compared based on a specific criteria. (D)</p> Signup and view all the answers

A reference type in Java that can contain only constants, method signatures, default methods, static methods, and nested types.

A class can implement multiple interfaces, providing method definitions for methods declared in those interfaces.

When a class implements an interface, it must provide concrete implementations for all methods declared in that interface.

Java does not support multiple inheritance with classes to avoid ambiguity, but allows it with interfaces.

Interfaces allow different classes to be treated the same way if they share the same interface, promoting flexibility and decoupling.

The ability of different classes to be treated as instances of the same class through an interface.

Using interfaces to reduce dependencies between higher and lower level classes.

Methods declared in an interface that must be implemented in the implementing class.

Java's inheritance model where a class can inherit from only one superclass.

When a class provides a concrete implementation for all abstract methods defined in an interface.

Helper classes declared within another class, often used in graphical applications.

Interfaces in graphical applications that respond to user actions like clicks or key presses.

Interfaces are created in separate files from classes.

Methods in interfaces are declared without implementation and end with ';'.

Constants in interfaces can be used as if defined in a class.

A class implementing an interface guarantees to provide specific behavior.

The compiler verifies that all abstract methods are implemented in implementing classes.

Interfaces cannot be instantiated directly; they must be implemented by classes.

Converting one object type to another, e.g., from Object to Coin.

Occurs if an object is cast to an incompatible type, throwing a runtime error.

When converting, you must use casting: className = interfaceName.

You can assign directly if the class implements the interface.

Provide polymorphism and reduce dependencies, simplifying designs.

Slower performance and rigid method definitions that prevent modifications post-creation.

Binding that is resolved at runtime based on the object's actual type.

A form of dynamic binding where method calls are resolved at execution time.

Binding that is resolved at compile time, often seen with overloaded methods.

A method that different objects override to provide specific behavior.

An interface requires implementing classes to define specified methods.

Defining multiple methods with the same name but different parameters.

Interfaces define what actions can be done while implementations define how those actions are carried out.

An error when an object can't be cast to a specific class type.

An interface representing anything that can fly or be airborne.

Using interfaces allows objects of different classes to be treated as the same type.

Some casts are allowed if types are compatible, others are not.

Classes like SkiJumper can implement Athlete, gaining its attributes.

A list that can hold any object that implements the Flier interface.

A Flier can reference only those objects that implement it, not specific classes unless safely cast.