Starting Out with Java: From Control Structures through Objects (7th Edition) (What's New in Computer Science)
7th Edition
ISBN: 9780134802213
Author: Tony Gaddis
Publisher: PEARSON
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Chapter 4, Problem 18AW
Program Plan Intro
Scanner and File class:
The Scanner class helps to create the object for Scanner method for reading the input strings from console and inputs are delimited by whitespace characters.
The syntax to create an object for Scanner class using System.in is given below:
Scanner objName = new Scanner(System.in);
Instead of reading input using “System.in”, the “Scanner” class can read input from the file using “File” class object. The user should pass “File” class object in the “Scanner” class constructor to open a file for reading.
File myFile =new File("Sales.txt");
Scanner inputFile = new Scanner(myFile);
Here,
- “myFile” is the “File” class object
- “Sales.txt” is the file to be opened for reading
- “inputFile” is the “Scanner” class object.
- “myFile” is passed as an argument in the “Scanner” class constructor.
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Write code that does the following: opens a file named MyName.txt, reads the first linefrom the file and displays it, and then closes the file.
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Example:
If the content of numbers.txt is: 10 20 30 100
The program should print: 160
Use num.txt file (below). create a program that opens num.txt, a file consisting of a series of integers. Display all of the numbers in the file.
num.txt
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54
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Chapter 4 Solutions
Starting Out with Java: From Control Structures through Objects (7th Edition) (What's New in Computer Science)
Ch. 4.1 - What will the following program segments display?...Ch. 4.2 - How many times will Hello World be printed in the...Ch. 4.2 - How many times will I love Java programming! be...Ch. 4.3 - Write an input validation loop that asks the user...Ch. 4.3 - Write an input validation loop that asks the user...Ch. 4.3 - Write an input validation loop that asks the user...Ch. 4.5 - Name the three expressions that appear inside the...Ch. 4.5 - You want to write a for loop that displays I love...Ch. 4.5 - What will the following program segments display?...Ch. 4.5 - Write a for loop that displays your name 10 times.
Ch. 4.5 - Write a for loop that displays all of the odd...Ch. 4.5 - Write a for loop that displays every fifth number,...Ch. 4.6 - Write a for loop that repeats seven times, asking...Ch. 4.6 - In the following program segment, which variable...Ch. 4.6 - Prob. 4.15CPCh. 4.10 - What is the difference between an input file and...Ch. 4.10 - What import statement will you need in a program...Ch. 4.10 - What class do you use to write data to a file?Ch. 4.10 - Write code that does the following: opens a file...Ch. 4.10 - What classes do you use to read data from a file?Ch. 4.10 - Write code that does the following: opens a file...Ch. 4.10 - You are opening an existing file for output. How...Ch. 4.10 - What clause must you write in the header of a...Ch. 4.11 - Assume x is an int variable, and rand references a...Ch. 4.11 - Assume x is an int variable, and rand references a...Ch. 4.11 - Assume x is an int variable, and rand references a...Ch. 4.11 - Assume x is a double variable, and rand references...Ch. 4 - What will the println statement in the following...Ch. 4 - Prob. 2MCCh. 4 - Prob. 3MCCh. 4 - What is each repetition of a loop known as? a....Ch. 4 - This is a variable that controls the number of...Ch. 4 - The while loop is this type of loop. a. pretest b....Ch. 4 - The do-while loop is this type of loop. a. pretest...Ch. 4 - The for loop is this type of loop. a. pretest b....Ch. 4 - This type of loop has no way of ending and repeats...Ch. 4 - This type of loop always executes at least once....Ch. 4 - This expression is executed by the for loop only...Ch. 4 - Prob. 12MCCh. 4 - This is a special value that signals when there...Ch. 4 - To open a file for writing, you use the following...Ch. 4 - To open a file for reading, you use the following...Ch. 4 - Prob. 16MCCh. 4 - This class allows you to use the print and println...Ch. 4 - This class allows you to read a line from a file....Ch. 4 - True or False: The while loop is a pretest loop.Ch. 4 - True or False: The do-while loop is a pretest...Ch. 4 - True or False: The for loop is a posttest loop.Ch. 4 - True or False: It is not necessary to initialize...Ch. 4 - True or False: One limitation of the for loop is...Ch. 4 - True or False: A variable may be defined in the...Ch. 4 - True or False: In a nested loop, the inner loop...Ch. 4 - True or False: To calculate the total number of...Ch. 4 - // This code contains ERRORS! // It adds two...Ch. 4 - Prob. 2FTECh. 4 - // This code contains ERRORS! int choice, num1,...Ch. 4 - Prob. 4FTECh. 4 - Write a while loop that lets the user enter a...Ch. 4 - Write a do-whi1e loop that asks the user to enter...Ch. 4 - Write a for loop that displays the following set...Ch. 4 - Write a loop that asks the user to enter a number....Ch. 4 - Write a for loop that calculates the total of the...Ch. 4 - Write a nested loop that displays 10 rows of #...Ch. 4 - Convert the while loop in the following code to a...Ch. 4 - Convert the do-while loop in the following code to...Ch. 4 - Convert the following while loop to a for loop:...Ch. 4 - Convert the following for loop to a while loop:...Ch. 4 - Write an input validation loop that asks the user...Ch. 4 - Write an input validation loop that asks the user...Ch. 4 - Write nested loops to draw this pattern:Ch. 4 - Write nested loops to draw this pattern: ## # # #...Ch. 4 - Complete the following program so it displays a...Ch. 4 - Complete the following program so it performs the...Ch. 4 - Prob. 17AWCh. 4 - Prob. 18AWCh. 4 - Modify the code you wrote in Question 18 so it...Ch. 4 - Write code that opens a file named NumberList.txt...Ch. 4 - Prob. 1SACh. 4 - Why should you indent the statements in the body...Ch. 4 - Describe the difference between pretest loops and...Ch. 4 - Why are the statements in the body of a loop...Ch. 4 - Describe the difference between the while loop and...Ch. 4 - Which loop should you use in situations where you...Ch. 4 - Which loop should you use in situations where you...Ch. 4 - Which loop should you use when you know the number...Ch. 4 - Why is it critical that accumulator variables are...Ch. 4 - What is an infinite loop? Write the code for an...Ch. 4 - Describe a programming problem that would require...Ch. 4 - What does it mean to let the user control a loop?Ch. 4 - What is the advantage of using a sentinel?Ch. 4 - Prob. 14SACh. 4 - Describe a programming problem requiring the use...Ch. 4 - How does a file buffer increase a programs...Ch. 4 - Why should a program close a file when its...Ch. 4 - What is a files read position? Where is the read...Ch. 4 - When writing data to a file, what is the...Ch. 4 - What does the Scanner classs hasNext method return...Ch. 4 - What is a potential error that can occur when a...Ch. 4 - Prob. 22SACh. 4 - How do you open a file so that new data will be...Ch. 4 - Sum of Numbers Write a program that asks the user...Ch. 4 - Distance Traveled The distance a vehicle travels...Ch. 4 - Distance File Modify the program you wrote for...Ch. 4 - Pennies for Pay Write a program that calculates...Ch. 4 - Prob. 5PCCh. 4 - File Letter Counter Write a program that asks the...Ch. 4 - Hotel Occupancy A hotels occupancy rate is...Ch. 4 - Average Rainfall Write a program that uses nested...Ch. 4 - Population Write a program that will predict the...Ch. 4 - Largest and Smallest Write a program with a loop...Ch. 4 - Celsius to Fahrenheit Table Write a program that...Ch. 4 - Bar Chart Write a program that asks the user to...Ch. 4 - File Head Display Write a program that asks the...Ch. 4 - Line Numbers Write a program that asks the user...Ch. 4 - Uppercase File Converter Write a program that asks...Ch. 4 - Budget Analysis Write a program that asks the user...Ch. 4 - Random Number Guessing Game Write a program that...Ch. 4 - Random Number Guessing Game Enhancement Enhance...Ch. 4 - ESP Game Write a program that tests your ESP...Ch. 4 - Square Display Write a program that asks the user...Ch. 4 - Dice Game Write a program that plays a simple dice...Ch. 4 - Prob. 22PCCh. 4 - Personal Web Page Generator Write a program that...
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