Keyboard Input

14. Asking Questions - Link

Task
Output
Question

It’s now time to pick up the pace a bit. I’ve got you doing a lot of printing so that you get used to typing simple things, but those simple things are fairly boring. What we want to do now is get you getting data into your programs. This though is a little tricky so we have to have you learn to do two things that may not make sense right away, but if you stick with it they should click suddenly a few exercises from now.Most of what software does is the following:

Take some kind of input from a person.
Change it.
Print out something to show how it changed.

So far you’ve only been printing, but you haven’t been able to get any input from a person, or change it. You may not even know what “input” means, so rather than talk about it, let’s have you do some and see if you get it. Next exercise we’ll do more to explain it.

AskingQuestions.java

import java.util.Scanner;

public class AskingQuestions
{
    public static void main( String[] args )
    {
        Scanner keyboard = new Scanner(System.in);

        int age;
        String height;
        double weight;

        System.out.print( "How old are you? " );
        age = keyboard.nextInt();

        System.out.print( "How tall are you? " );
        height = keyboard.next();

        System.out.print( "How much do you weigh? " );
        weight = keyboard.nextDouble();

        System.out.println( "So you're " + age + " old, " + height + " tall and " + weight + " heavy." );
    }
}

Notice that we used print instead of println. This is so that the program doesn’t end the line with a newline and go to the next line.

U:\My Documents\CompSci\>java AskingQuestions
How old are you? 35
How tall are you? 6'2"
How much do you weigh? 180
So, you're 35 old, 6'2" tall and 180 heavy.

U:\My Documents\CompSci\>

Assignments turned in without these things will not receive any points.

Change the program so that it reads in the height in two parts. The first part should read in an int for the number of feet. Then read in a second int for the number of inches. Try to make the output look the same, though.

How old are you? 35
How many feet tall are you? 6
And how many inches? 2
How much do you weigh? 180
So, you're 35 old, 6'2" tall and 180 heavy.

Answer :

AskingQuestions.java

import java.util.Scanner;

public class AskingQuestions
{
    public static void main( String[] args )
    {
        Scanner keyboard = new Scanner(System.in);

        int age, feet, inches;
        double weight;

        System.out.print("How old are you? ");
        age = keyboard.nextInt();

        System.out.print("How many feet tall are you? ");
        feet = keyboard.nextInt();
        System.out.print("And how many inches? ");
        inches = keyboard.nextInt();

        System.out.print("How much do you weight? ");
        weight = keyboard.nextDouble();

        System.out.print("So you're " + age + " old, " + feet + "'" + inches + "\" tall and " + weight + " heavy.");
    }
}

15. The Forgetful Machine - Link

Task
Answer
Output

Ask the user for two words and two numbers, and let the person at the keyboard type in some values, but don’t bother storing their responses into any variables.Again, there is no need to create any variables, except for the Scanner variable typically named keyboard.

Give me a word!
lorry!
Give me a second word!
deoxyribonucleic?

Great, now your favorite number?
42
And your second-favorite number...
1

Whew!  Wasn't that fun?

ForgetfulMachine.java

import java.util.Scanner;

public class ForgetfulMachine
{
    public static void main( String[] args )
    {
        Scanner keyboard = new Scanner(System.in);

        System.out.println("Give me a word!");
        keyboard.next();
        System.out.println("Give me a second word!");
        keyboard.next();
        System.out.println("\nGreat, now your favorite number?");
        keyboard.nextInt();
        System.out.println("And your second-favorite numbber...");
        keyboard.nextInt();

        System.out.println("\nWhew! Wasn't that fun?");
    }
}

U:\My Documents\CompSci\>java ForgetfulMachine
Give me a word!
muqoffin
Give me a second word!
nuha

Great, now your favorite number?
5
And your second-favorite numbber...
10

Whew! Wasn't that fun?

U:\My Documents\CompSci\>

16. Name, Age, and Salary - Link

Task
Answer
Output

Ask the user for their name. Then display their name to prove that you can recall it. Ask them for their age. Then display that. Finally, ask them for how much they make and display that. You should use the most appropriate data type for each variable.

Hello.  What is your name?
Dennis 

Hi, Dennis!  How old are you?
37 

So you're 37, eh?  That's not old at all!
How much do you make, Dennis?
8.50 

8.5!  I hope that's per hour and not per year! LOL!

Hello.  What is your name?
Catsup 

Hi, Catsup!  How old are you?
12 

So you're 12, eh?  That's not old at all!
How much do you make, Catsup?
99.9 

99.9!  I hope that's per hour and not per year! LOL!

NameAgeAndSalary.java

import java.util.Scanner;

public class NameAgeAndSalary
{
    public static void main( String[] args )
    {
        Scanner keyboard = new Scanner(System.in);

        String name;
        int age;
        double salary;

        System.out.println("Hello. What is your name?");
        name = keyboard.next();

        System.out.println("\nHi, " + name + "! How old are you?");
        age = keyboard.nextInt();

        System.out.println("\nSo you're " + age + ", eh? That's not old at all!");
        System.out.println("How much do you make, " + name + "?");
        salary = keyboard.nextDouble();

        System.out.println("\n" + salary + "! I hope that's per hour and not per year! LOL!");
    }
}

U:\My Documents\CompSci\>java NameAgeAndSalary
Hello. What is your name?
Muqoffin

Hi, Muqoffin! How old are you?
21

So you're 21, eh? That's not old at all!
How much do you make, Muqoffin?
1000

1000.0! I hope that's per hour and not per year! LOL!

U:\My Documents\CompSci\>

17. More User Input of Data - Link

Task
Answer
Output

Ask the user for several pieces of information, and display them on the screen afterward as a summary.

first name
last name
grade (classification)
student id number
login name
GPA (0.0 to 4.0) You must use the most appropriate type for each variable and not just Strings for everything.

Please enter the following information so I can sell it for a profit!

First name: Helena
Last name: Bonham-Carter
Grade (9-12): 12
Student ID: 453916
Login: bonham_453916
GPA (0.0-4.0): 3.73

Your information:
    Login: bonham_453916
    ID:    453916
    Name:  Bonham-Carter, Helena
    GPA:   3.73
    Grade: 12

MoreUserInputOfData.java

import java.util.Scanner;

public class MoreUserInputOfData
{
    public static void main( String[] args )
    {
        Scanner keyboard = new Scanner(System.in);

        String firstName, lastName, login, studentID;
        int grade;
        double gpa;

        System.out.println("Please enter the following information so I can sell it for a profit!\n");

        System.out.print("First name: ");
        firstName = keyboard.next();
        System.out.print("Last name: ");
        lastName = keyboard.next();
        System.out.print("Grade (9-12): ");
        grade = keyboard.nextInt();
        System.out.print("Student ID: ");
        studentID = keyboard.next();
        System.out.print("Login: ");
        login = keyboard.next();
        System.out.print("GPA (0.0-4.0): ");
        gpa = keyboard.nextDouble();

        System.out.println("\nYour information:");
        System.out.println("\tLogin:  "+login);
        System.out.println("\tID:     "+studentID);
        System.out.println("\tName:   "+lastName+", "+firstName);
        System.out.println("\tGPA:    "+gpa);
        System.out.println("\tGrade:  "+grade);
    }
}

U:\My Documents\CompSci\>java MoreUserInputOfData
Please enter the following information so I can sell it for a profit!

First name: Muqoffin
Last name: Nuha
Grade (9-12): 12
Student ID: 123456
Login: muqoffin_123456
GPA (0.0-4.0): 3.5

Your information:
    Login: muqoffin_123456
    ID:    123456
    Name:  Nuha, Muqoffin
    GPA:   3.5
    Grade: 12

U:\My Documents\CompSci\>

18. Age in Five Years - Link

Task
Answer
Output

Ask the user for their name. Then display their name to prove that you can recall it. Ask them for their age. Then display what their age would be five years from now. Then display what their age would be five years ago.

Hello.  What is your name? Percy_Bysshe_Shelley

Hi, Percy_Bysshe_Shelley!  How old are you? 34

Did you know that in five years you will be 39 years old?
And five years ago you were 29! Imagine that!

Hello.  What is your name? Gramps

Hi, Gramps!  How old are you? 87

Did you know that in five years you will be 92 years old?
And five years ago you were 82! Imagine that!

AgeIn5.java

import java.util.Scanner;

public class AgeIn5
{
    public static void main( String[] args )
    {
        Scanner keyboard = new Scanner(System.in);

        String name;
        int age;

        System.out.print("Hello. What is your name? ");
        name = keyboard.next();

        System.out.print("\nHi, " + name + "! How old are you? ");
        age = keyboard.nextInt();

        System.out.println("\nDid you know that in five years you will be " + (age + 5) + " years old?");
        System.out.println("And five years ago you were " + (age - 5) + "! Imagine that!");
    }
}

U:\My Documents\CompSci\>java AgeIn5
Hello. What is your name? Muqoffin

Hi, Muqoffin! How old are you? 21

Did you know that in five years you will be 26 years old?
And five years ago you were 16! Imagine that!

U:\My Documents\CompSci\>

19. A Dumb Calculator - Link

Task
Answer
Output

Make a simple numeric calculator. It should prompt the user for three numbers. Then add the numbers together and divide by 2. Display the result. Your program must support numbers with decimals and not just integers.

U:\>java DumbCalculator

What is your first number? 1.1
What is your second number? 2.2
What is your third number? 5.5

( 1.1 + 2.2 + 5.5 ) / 2 is... 4.4

DumbCalculator.java

import java.util.Scanner;

public class DumbCalculator
{
    public static void main( String[] args )
    {
        Scanner keyboard = new Scanner(System.in);

        double firstNumber, secondNumber, thirdNumber, results;

        System.out.print("What is your first number? ");
        firstNumber = keyboard.nextDouble();
        System.out.print("What is your second number? ");
        secondNumber = keyboard.nextDouble();
        System.out.print("What is your third number? ");
        thirdNumber = keyboard.nextDouble();

        results = (firstNumber + secondNumber + thirdNumber) / 2;

        System.out.println("\n( " + firstNumber + " + " + secondNumber + " + " + thirdNumber + " ) / 2 is... " + results);
    }
}

U:\My Documents\CompSci\>java DumbCalculator
What is your first number? 1.1
What is your second number? 2.2
What is your third number? 5.5

( 1.1 + 2.2 + 5.5 ) / 2 is... 4.4

U:\My Documents\CompSci\>

20. BMI Calculator - Link

Task
Answer
Bonus

(This assignment was suggested by Joel H in 2012.)The body mass index (BMI) is commonly used by health and nutrition professionals to estimate human body fat in populations.It is computed by taking the individual’s weight (mass) in kilograms and dividing it by the square of their height in meters.

Your height in m: 1.75
Your weight in kg: 73

Your BMI is 23.83673

BMICalc.java

import java.util.Scanner;

public class BMICalc
{
    public static void main( String[] args )
    {
        Scanner keyboard = new Scanner(System.in);

        double height, weight, bmi;

        System.out.print("Your height in m: ");
        height = keyboard.nextDouble();
        System.out.print("Your weight in kg: ");
        weight = keyboard.nextDouble();

        bmi = weight / Math.pow(height, 2);

        System.out.printf("\nYour BMI is %.5f", bmi);
    }
}

Bonus #1 - Imperial Measurements

For +10 bonus points, input their weight and height using pounds and inches, and convert to kilograms and meters to figure the BMI.

Your height in inches: 69
Your weight in pounds: 160

Your BMI is 23.625289

Answer :

BMICalc.java

import java.util.Scanner;

public class BMICalc
{
    public static void main( String[] args )
    {
        Scanner keyboard = new Scanner(System.in);

        double height, weight, bmi;

        System.out.print("Your height in inches: ");
        height = keyboard.nextDouble();
        System.out.print("Your weight in pounds: ");
        weight = keyboard.nextDouble();

        height = height * 0.0254;
        weight = weight * 0.453592;

        bmi = weight / Math.pow(height, 2);

        System.out.printf("\nYour BMI is %.6f", bmi);
    }
}

For an extra +3 bonus points (+13 total), input their height in feet and inches.

Your height (feet only): 5
Your height (inches): 9
Your weight in pounds: 160

Your BMI is 23.625289

Answer :

BMICalc.java

import java.util.Scanner;

public class BMICalc
{
    public static void main( String[] args )
    {
        Scanner keyboard = new Scanner(System.in);

        double height, weight, bmi, feet, inches;

        System.out.print("Your height (feet only): ");
        feet = keyboard.nextDouble();
        System.out.print("Your height (inches): ");
        inches = keyboard.nextDouble();
        System.out.print("Your weight in pounds: ");
        weight = keyboard.nextDouble();

        height = (feet * 12 + inches) * 0.0254;
        weight = weight * 0.453592;

        bmi = weight / Math.pow(height, 2);

        System.out.printf("\nYour BMI is %.6f", bmi);
    }
}

Persiapan Belajar

Materi

Task

Programming by Doing

Compiler

Keyboard Input

14. Asking Questions - Link

15. The Forgetful Machine - Link

16. Name, Age, and Salary - Link

17. More User Input of Data - Link

18. Age in Five Years - Link

19. A Dumb Calculator - Link

20. BMI Calculator - Link

​14. Asking Questions - Link

​15. The Forgetful Machine - Link

​16. Name, Age, and Salary - Link

​17. More User Input of Data - Link

​18. Age in Five Years - Link

​19. A Dumb Calculator - Link

​20. BMI Calculator - Link

14. Asking Questions - Link

15. The Forgetful Machine - Link

16. Name, Age, and Salary - Link

17. More User Input of Data - Link

18. Age in Five Years - Link

19. A Dumb Calculator - Link

20. BMI Calculator - Link