Exam 11: Advanced Inheritance Concepts

When you create a class that uses an interface, you include the keyword extends .

public class Animal { } public class Animal extends Object { } The two class declarations above have identical outcomes. Explains why this is the case.

While a class can inherit from multiple abstract superclasses, it can implement only one interface.

If you provide an empty method within an abstract class, the method is an abstract method even if you do not explicitly use the keyword ____ when defining the method.

public abstract class Car {     private String model;     public abstract void color();     public String getName()     {         return model;      }      public void setName(String carModel)      {         model = carModel;       } } Using the code above, would it be possible to create a class in which you declare a Car object with the statement Car myCar = new Car("Honda"); ? Explain why or why not.

____ compress the data they store, which reduces the size of archived class files.

public abstract class Car {     private String model;     public abstract void color();     public String getModel()     {          return model;      }     public void setModel(String modelName)     {          model = modelName;      } } ​ public class Honda extends Car {     public void color()     { System.out.println("red");     } } ​ public class Ford extends Car {     public void color()     {       System.out.println("blue");     } } ​ public class MyCars {     public static void main(String[] args)     {        Honda myHonda = new Honda();        Ford myFord = new Ford();   myHonda.setModel("My Honda is ");        myFord.setModel("My Ford is ");   System.out.print(myHonda.getModel());   myHonda.color();   System.out.print(myFord.getModel());   myFord.color();     } } In the above code, the myHonda.getModel() and myHonda.color() method calls produce different output from when the same methods are used with myFord . Explain why this is the case.

Instead of using the automatic toString() method with your classes, it is usually more useful to write your own ____ version of the toString() method that displays some or all of the data field values for the object with which you use it.

Java does not allow a class to inherit directly from two or more parents.

A functional interface ____.

Classes, such as the String class, have their own equals() methods that overload the ____ class method.

public interface FindTheError {     void firstMethod(int anIntNum)    {         System.out.println("Did you find the error?");    } } What is the problem with the above interface? How would you correct the interface?

The equals() method returns a boolean value indicating whether two objects are equal. Using the above code, will the two BankAccount objects be equal? Explain why or why not.

The capability to inherit from more than one class is called ____.

The Object class ____ method converts an Object into a String that contains information about the Object .

Compare and contrast abstract classes and interfaces.

Java's Object class contains a public method named ____ that returns an integer representing the hash code.

The java.lang package contains fundamental classes and is imported automatically each time a program is written.

When a superclass is abstract, you cannot instantiate objects of a superclass. How can you use a superclass abstract object?