Chapter 3a - User Input

Scanner

Scanning for User Input

import java.util.*;
class Main {
    public static void main(String arg[]) {
      System.out.print("Enter Your Name : ");  // user prompt
      Scanner sc = new Scanner(System.in);     // take user input
      String name = sc.nextLine();             // store the user input in the name variable
      System.out.println("Name : "+ name);     // output the value stored in name
    }
}

🧪 Try the code out~!

🙋‍♀️ What's also imported from Java Util?

Here is a list of al the things we are importing when we write:

import java.util.*

https://docs.oracle.com/javase/8/docs/api/java/util/package-summary.html

Methods for accepting user Input

Code	What is used for
nextInt()	It is used to take an integer as an input.
nextFloat()	It is used to take float as an input.
nextDouble()	It is used to take double as an input.
nextLine()	It is used to take String as an input(It will accept a line).
nextBoolean()	It is used to take the boolean value as an input.
nextLong()	It is used to take long as an input.

Asking for a char

The following line will save the first letter on the next line
To do that we are using charAt(0) which means The character that is on the index 0 (we start counting from 0 as the first letter)

char character = sc.nextLine().charAt(0);

Number Inputs

👀 Lesson 3 Learning Activities [E1] : Prediction with User Inputs in Java

Example: Bake Store Program

In this example we create a Program for a Bake Bar that helps the store clerk into calculating the total cost of the items the customer purchases.

import java.util.*;
class Main {
    public static void main(String args[]) {
        Scanner scan = new Scanner(System.in);
        System.out.println("------------------------------------------------");
        System.out.println("The following items are availabe at Bake Bar: ");
        System.out.println("Shortcakes at $1.5 per cake");
        System.out.println("Macaron at $1 per piece");
        System.out.println("Chocochip cookies at $1 per cookie");
        System.out.println("-------------------------------------------------");
        System.out.print("Enter the number of shortcakes you want: ");
        int shortcake = scan.nextInt();
        System.out.print("Enter the number of macarons you want: ");
        int macaron = scan.nextInt();
        System.out.print("Enter the number of cookies you want: ");
        int cookie = scan.nextInt();
        double costCake = 1.5 * shortcake; //calculate the money spent on shortcake
        double costMacaron = 1 * macaron; // calculate the money spent on macarons
        double costCookie = 1 * cookie; // calculate the money spent on cookies
        double totalCost = costCake + costMacaron + costCookie;
        //calculate the total money spent on all 3 items
        System.out.println("Bill amount for your shopping is $" + totalCost);
    }
}

🧪 Try the code out!

No need to store inputs

The following code works just fine too!

System.out.println("Enter Your Name");
Scanner sc=new Scanner(System.in);
System.out.println(sc.nextLine());

Create a Madlib

👀 Madlib Exercise

Create the following Program

Take user inputs for words to fill in the blanks.
Be sure to provide appropriate prompts to let your user know what she/he should be entering.
Print out the completed madlib using string concatenation.
You may store the text blocks for your madlib in variables or use them directly as strings for concatenation when you output.

Sample Program

✍ Solve the problem using Replit

Feel free to use Repl, you can fork from this empty canvas in Repl.it

✍ You can solve the problem here using Trinket

Steps

Complete The following code so that it scans for the noun and prints the noun entered.
Complete the code so that it also asks for the adverb. Feel free to uncomment line 13
Complete the code so that it also ask the verb. Feel free to uncomment line 14
Scan and print the adjective. Feel free to uncomment line 15

Exercise: Improving the Bake Shop

The following code only have the following menu items on it.

Item	Price
Cake	$1.5
Macaron	$1
Cookie	$1

🔨 Modify this code so that now you have a menu itme available: e.g.:

Item	Price
Bread	$5

import java.util.*;
class Main {
    public static void main(String args[]) {
        Scanner scan = new Scanner(System.in);
        System.out.println("------------------------------------------------");
        System.out.println("The following items are availabe at Bake Bar: ");
        System.out.println("Shortcakes at $1.5 per cake");
        System.out.println("Macaron at $1 per piece");
        System.out.println("Chocochip cookies at $1 per cookie");
        System.out.println("-------------------------------------------------");
        System.out.print("Enter the number of shortcakes you want: ");
        int shortcake = scan.nextInt();
        System.out.print("Enter the number of macarons you want: ");
        int macaron = scan.nextInt();
        System.out.print("Enter the number of cookies you want: ");
        int cookie = scan.nextInt();
        double costCake = 1.5 * shortcake; //calculate the money spent on shortcake
        double costMacaron = 1 * macaron; // calculate the money spent on macarons
        double costCookie = 1 * cookie; // calculate the money spent on cookies
        double totalCost = costCake + costMacaron + costCookie;
        //calculate the total money spent on all 3 items
        System.out.println("Bill amount for your shopping is $" + totalCost);
    }
}

✍ You can solve the problem here using Trinket

Scanner​

Scanning for User Input​

Methods for accepting user Input​