Practice Exam I Questions

If number is 20, what is printed to the console after this code is executed? for (int i = 3; i <= number; i += 2) { if (number % i == 0) { System.out.println(i); if (i == number) { System.out.println("special"); } break; } }

5

If the value of the int variable named quantity is 5, what is the value of total after this statement is executed? int total=quantity++

5

What is the value of x after the following statements are executed? int x = 5; switch(x) { case 5: x += 2; case 6: x++; break; default: x *= 2; break; }

8

If the variable named percent is 0.0755, what is the value of p after this statement is executed? String p = NumberFormat.getPercentInstance().format(percent);

8%

If the variable named percent is 0.0755, what is the value of p after this statement is executed? String p = NumberFormat.getPercentInstance().format(percent);

8%

Based on the naming recommendations in the book, which of the following is a good identifier for a constant that will be used to hold a base shipping charge?

BASE_SHIPPING_CHARGE

Which of the following statements creates a BigDecimal variable named decimalSubtotal from a double variable named subtotal, making sure that conversion problems are avoided.

BigDecimal decimalSubtotal = new BigDecimal(Double.toString(subtotal));

Code example 2-1 import java.util.Scanner; public class InvoiceApp { public static void main(String[] args) { Scanner sc = new Scanner(System.in); String choice = "y"; while (choice.equals("y")) { System.out.print("Enter subtotal: "); double subtotal = sc.nextDouble(); double salesTax = subtotal * .0875; double invoiceTotal = subtotal + salesTax; String message = "Subtotal = " + subtotal + "\n" + " Sales tax = " + salesTax + "\n" + "Invoice total = " + invoiceTotal + "\n\n" System.out.println(message); System.out.print("Continue? Enter y or n: "); choice = sc.next(); } } } (Refer to code example 2-1.) The name of the file that contains this source code must be

InvoiceApp.java

Which of the following is not a feature of using an Installer program to deploy an application?

It automatically updates the application when a new version is available

What is the main reason for coding a method to validate a specific type of entry?

It saves you from writing variations of the same code again and again to check multiple data entries.

Code example 2-1 import java.util.Scanner; public class InvoiceApp { public static void main(String[] args) { Scanner sc = new Scanner(System.in); String choice = "y"; while (choice.equals("y")) { System.out.print("Enter subtotal: "); double subtotal = sc.nextDouble(); double salesTax = subtotal * .0875; double invoiceTotal = subtotal + salesTax; String message = "Subtotal = " + subtotal + "\n" + " Sales tax = " + salesTax + "\n" + "Invoice total = " + invoiceTotal + "\n\n" System.out.println(message); System.out.print("Continue? Enter y or n: "); choice = sc.next(); } } } (Refer to code example 2-1.) If the user enters "Y" when asked if he/she wants to continue, the application will

It will terminate

Which of the following is not true of using a IDE to develop Java programs

It's harder to detect syntax errors

In Java, exceptions are

Objects

What must you do if you code an infinite loop in an application?

Stop the application to end the loop

Which of the following statements uses a Scanner variable named sc to return the next value the user enters at the consolse as a String object and store it in a variable named city?

String city = sc.next();

Which of the following statements converts a double variable named subtotal to a String object named subtotalString?

String subtotalString = Double.toString(subtotal);

Which of the following statements prints a variable named total to the console, followed by a next line character?

System.out.println(total);

Consider the code that follows. What does it do? String value = "2"; boolean tryAgain = true; while (tryAgain == true) { try { int num = Integer.parseInt(value); tryAgain = false; } System.out.println("Valid integer"); catch(NumberFormatException nfe) { System.out.println("Invalid integer"); System.out.print("Enter an integer"); value = sc.next } }

The code doesn't compile

Output example 5-1 Exception in thread "main" java.util.InputMismatchException at java.util.Scanner.throwFor(Scanner.java:818) at java.util.Scanner.next(Scanner.java:1420) at java.util.Scanner.nextDouble(Scanner.java:2324) at FutureValueApp.main(FutureValueApp.java:17) (Refer to output example 5-1.) What caused the exception to occur?

The user didn't enter the type of data the program was expecting

What does the following statement do if userNumber has an integer value of 14 and userEntry has a string value of "two"? userNumber = Integer.parseInt(userEntry);

Throws an exception

Which of the following is not a benefit of a typical IDE for Java?

Your code compiles and runs faster

Output example 5-1 Exception in thread "main" java.util.InputMismatchException at java.util.Scanner.throwFor(Scanner.java:818) at java.util.Scanner.next(Scanner.java:1420) at java.util.Scanner.nextDouble(Scanner.java:2324) at FutureValueApp.main(FutureValueApp.java:17) (Refer to output example 5-1.) What is this output called?

a stack trace

Output example 5-1 Exception in thread "main" java.util.InputMismatchException at java.util.Scanner.throwFor(Scanner.java:818) at java.util.Scanner.next(Scanner.java:1420) at java.util.Scanner.nextDouble(Scanner.java:2324) at FutureValueApp.main(FutureValueApp.java:17) (Refer to output example 5-1.) What is the order of method calls?

a. FutureValueApp.main calls java.util.Scanner.nextDouble calls java.util.Scanner.next calls java.util.Scanner.throwFor

In a do-while loop, the Boolean expression is tested

after the loop is executed

Using the BigDecimal class, you can

avoid rounding errors that may occur otherwise in business application

Which of these data types are used to store true or false values

boolean

The goal of testing is to

find all errors in the application

Which of these data types are used to store numbers with decimal positions?

float

Which of the following formats can you not apply using the NumberFormat class?

fraction

Which of the following is not a binary operator?

++

What happens in the method that follows when s is "two"? public double parseInterval(String s) { double interval = 0.0; try { interval = Double.parseDouble(s); } catch(NumberFormatException e) { } return interval; }

0.0 is returned

What is the range of values that x can hold after this statement is executed? double x = Math.random() * 10 + 100;

100 <= x < 110

If int variable x = 100, float variable y = 1.587F, and double variable z = 4.8, what does the following expression return? x + Math.round(y) + (int) z

106

Assume that before the following code is executed, the value of totalOne is 6.728, the value of totalTwo is 116, and both are BigDecimal objects. What is the value of totalFinal after the code is executed? totalOne = totalOne.setScale(2, RoundingMode.HALF_UP); BigDecimal totalFinal = totalTwo.add(totalOne);

122.73

If the int variables a = 5, b = 2, and c = 10, what is the value of c after the following statement is executed? c = c + a * b - 5;

15

Given a double variable named total with a value of 62.5 and an integer variable named quantity with a value of 4, what will the value of price be after you execute this statement?

15.625

When you're using an IDE's debugger and execution reaches a breakpoint, you can click

the Step Into button to execute the current statement and move to the next statement

What feature of an IDE can help you enter a method by displaying a list of methods that are available from an object or class?

the code completion feature

What happens when you use both integer and double values in an arithmetic expression

the integer values are cast to double values

What happens when you use both integer and double values in an arithmetic expression?

the integer values are cast to double values

A syntax error occurs when

there's a syntax error in a Java statement

If a class contains a main() method, that method is executed

when the class is run

The int data type can be used to store

whole numbers only

Which of the following statements calculates the change in sales between two double variables named this YTDSales and lastYTDSales, rounds the result to an integer, and stores it in an integer in an int variable named salesChange?

int salesChange = Math.round(thisYTDSales - lastYTDSales);

The extension for a Java source file is

java

What package is automatically available to all Java programs?

java.lang

Output example 5-1 Exception in thread "main" java.util.InputMismatchException at java.util.Scanner.throwFor(Scanner.java:818) at java.util.Scanner.next(Scanner.java:1420) at java.util.Scanner.nextDouble(Scanner.java:2324) at FutureValueApp.main(FutureValueApp.java:17) (Refer to output example 5-1.) Which statement would you look at to find the source of the problem?

line 17 in the FutureValueApp class

An error that lets the application run but produces the wrong results is known as a

logic error

Explicit cases can be use to perform

narrowing conversions

Unlike a data type, a reference type

points to the data in another area of internal storage

An IDE typically stores all of the files for an application in a

project

An error that occurs after an application is running is known as a

runtime error

You typically use comments in a Java application to

describe code that is difficult to understand

You can use a System.out object to:

display a blank line on a console

Code example 5-1 import java.util.Scanner; import java.text.NumberFormat; public class WeightConverter { public static void main(String[] args) { Scanner sc = new Scanner(System.in); String prompt = "Enter weight in lbs: "; boolean isValid = false; double weightInPounds = 0.0; while (!isValid) { weightInPounds = getDouble(sc, prompt); if (weightInPounds > 0) { isValid = true; } else { System.out.println("Weight must be greater than 0."); } } double weightInKilos = weightInPounds / 2.2; NumberFormat nf = NumberFormat.getNumberInstance(); nf.setMaximumFractionDigits(2); String message = weightInPounds + " lbs\nequals\n" + nf.format(weightInKilos) + " kgs\n"; System.out.print(message); } public static double getDouble(Scanner sc, String prompt) { double d = 0.0; boolean isValid = false; while (!isValid) { System.out.print(prompt); if (sc.hasNextDouble()) { d = sc.nextDouble(); isValid = true; } else { System.out.println ("Error! Invalid decimal value. Try again."); } sc.nextLine(); } return d; } } (Refer to code example 5-1.) If the user enters 118 at the console prompt, what is the third line of the resulting console display?

53.64 kgs

If the double variables x = 2.5 and y = 4.0, what is the value of z after this statement is executed? int z = (int) x + (int) y;

6

If the variable named input is 755, what is the value of r after these statements are executed? NumberFormat n = NumberFormat.getNumberInstance(); n.setMinimumFractionDigits(3); String r = n.format(input);

755.000

Code example 5-1 import java.util.Scanner; import java.text.NumberFormat; public class WeightConverter { public static void main(String[] args) { Scanner sc = new Scanner(System.in); String prompt = "Enter weight in lbs: "; boolean isValid = false; double weightInPounds = 0.0; while (!isValid) { weightInPounds = getDouble(sc, prompt); if (weightInPounds > 0) { isValid = true; } else { System.out.println("Weight must be greater than 0."); } } double weightInKilos = weightInPounds / 2.2; NumberFormat nf = NumberFormat.getNumberInstance(); nf.setMaximumFractionDigits(2); String message = weightInPounds + " lbs\nequals\n" + nf.format(weightInKilos) + " kgs\n"; System.out.print(message); } public static double getDouble(Scanner sc, String prompt) { double d = 0.0; boolean isValid = false; while (!isValid) { System.out.print(prompt); if (sc.hasNextDouble()) { d = sc.nextDouble(); isValid = true; } else { System.out.println ("Error! Invalid decimal value. Try again."); } sc.nextLine(); } return d; } } (Refer to code example 5-1.) What type of data validation does this program do?

Both range and valid data type checking

Which of the following is a valid calss name

CustomerMaintApp

What is the third line printed to the console in the code that follows? int items = 3; for (int i = 1; i <= items; i++) { int result = 1; for (int j = i; j >= 1; j--) { result *= j; } System.out.println("Factorial " + i + " = " + result); }

Factorial 3=6

What does debugging an application entail

Identifying and fixing any bugs

Which of the following statements creates an Integer object named countObject from an int variable named count?

Integer countObject = new Integer(count);

Which of the following statements do you use to jump to the end of a loop from within the loop?

break

A runtime error occurs when

bytecode can't be interpreted properly

Block scope means that the variable

can't be used outside of the set of braces it's declared in

Unlike an if/else statement, a switch statement

can't perform an operation based on he result of a boolean expression

Unlike a variable, a constant can't

change in value as an application runs

Unlike a variable, a constant can't

change in value as the application runs

In an IDE, what tool do you use to enter and edit source code?

code editor

Which of the following are two types of desktop applications that you can develop in Java?

console and GUI

Which of the following can you not use the Java API documentation to research?

debuggers

Code example 5-1 import java.util.Scanner; import java.text.NumberFormat; public class WeightConverter { public static void main(String[] args) { Scanner sc = new Scanner(System.in); String prompt = "Enter weight in lbs: "; boolean isValid = false; double weightInPounds = 0.0; while (!isValid) { weightInPounds = getDouble(sc, prompt); if (weightInPounds > 0) { isValid = true; } else { System.out.println("Weight must be greater than 0."); } } double weightInKilos = weightInPounds / 2.2; NumberFormat nf = NumberFormat.getNumberInstance(); nf.setMaximumFractionDigits(2); String message = weightInPounds + " lbs\nequals\n" + nf.format(weightInKilos) + " kgs\n"; System.out.print(message); } public static double getDouble(Scanner sc, String prompt) { double d = 0.0; boolean isValid = false; while (!isValid) { System.out.print(prompt); if (sc.hasNextDouble()) { d = sc.nextDouble(); isValid = true; } else { System.out.println ("Error! Invalid decimal value. Try again."); } sc.nextLine(); } return d; } }

displays an error message from the main() method

Which of the following is a valid statement for declaring and initializing a double variable named length to a starting value of 120?

double length = 120.0;

Based on the naming recommendations in the book, which of the following is a good identifier for a variable that will be used to hold an employee's phone number?

employeePhoneNumber