Question 1

Write a method called containsPair that takes in three integer parameters and returns true if any two of the input parameters are the same.

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Question 2

Consider the following method.

public void changeValues(int i, Card c)  {
		i = 15;
		c.setSuit(“Clubs”);
	}

Now consider the following snippet of code that calls the method defined above.

int num = 12;
	Card fiveOfSpades = new Card(5, “Spades”);

System.out.println(“Before method call:”);
	System.out.println(num);
	System.out.println(fiveOfSpades.getSuit());

changeValues(num, fiveOfSpades);

System.out.println(“After method call:”);
	System.out.println(num);
	System.out.println(fiveOfSpades);

What is the output of this code?

Accepted Answer

The answer of Consider the following method.

public void changeValues(int i,...

Question 3

Write a method called randomAverage that generates 100 random integers in the range 1 to 100 (inclusive) and returns their average. You may assume that the class has a static Random object called generator already declared and instantiated.

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Question 4

Write a method called square that takes in an integer value and returns the integer squared. Your method should use the Math.pow() method.

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Question 5

What is the difference between an object and a class?

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Question 6

Write a method called threeOfAKind that takes in three integer parameters and returns true if all three of them are the same, false otherwise.

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Question 7

Explain why method overloading is useful.

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Question 8

Variables that are declared as static are shared among all instances of a class.

Accepted Answer

Static variables are sometimes called class variables because they are shared among all instances of a class.

Question 9

A main method can only access static or local variables.

Accepted Answer

A main method cannot access non-static and non-local variables because it is a static method. In particular, it cannot access any variables declared at the class level.

Question 10

Explain the difference between actual parameters and formal parameters.

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Question 11

Write a method that prints your name, age, and major. The method should accept no parameters and return no value.

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Question 12

Write a method called isPalindrome that accepts a String as a parameter and returns true if the String is a palindrome, and false otherwise. You may assume that the entered String consists entirely of lowercase letters (meaning it contains no numbers, spaces, punctuation, etc). Hint: write code that creates a new string that is the original string reversed, and then check to see if the two strings are equal.

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The answer of Write a method called isPalindrome that accepts...

Question 13

A programmer is required to define a constructor for every class.

Accepted Answer

Every class automatically has a default constructor that doesn't take any parameters.

Question 14

What is encapsulation? How can it be enforced in Java?

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The answer of What is encapsulation? How can it be...

Question 15

Explain why a static method cannot refer to an instance variable.

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Question 16

In a class that has variables called height and width, methods called getHeight() and getWidth() are examples of accessor methods.

Accepted Answer

Accessor methods get the value of instance variables. In contrast, mutators set the values.

Question 17

Write a method called randomInRange that takes in two numbers representing a range. Print an error message and return zero if the second parameter is less than the first. Otherwise, the method should return a randomly generated integer in that range (inclusive). You may assume that the class has a static Random object called generator already declared and instantiated.

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Question 18

Write a method called countSpaces that takes in a String as a parameter and returns an integer that represents the number of space characters (' ') contained in the string, false otherwise..

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Question 19

Write a method called maxOfThree that accepts three integer parameters and returns the largest of the three.

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The answer of Write a method called maxOfThree that accepts...

Question 20

Aggregation is sometimes described as a has-a relationship.

Accepted Answer

Aggregate objects are made up of other objects. Therefore the relationship between an object that is an aggregate of other objects is often described as a has-a relationship.

Quiz 5: Writing Classes