While loop for input?

Question

I am beginner in learning java programming. Basically, I can't figure out the way to enter input from console multiple times after already previous input and processing data. Before I show you my code, I think it is a good idea to show how the result should be. The result of the program should be:

Please Enter either S(supply) or R(replenish) followed by ID and quantity.
R     p122.   10
New Stock-level for p122(Chain) is 58
S.    p124.   20
New Stock-level for p125(Pedal) is 18
S.    p905.   20
No part found with ID p905
.....// enter empty string to terminate

There are uses of a different class. I already be able to make my program works correctly with one line input.

Please Enter either S(supply) or R(replenish) followed by ID and quantity.
R     p122.   10
New Stock-level for p122(Chain) is 58

However, I cannot figure out how to let users enter input the second time and so on. I tried to include in a while loop but it does not work as expectation.

Please Enter either S(supply) or R(replenish) followed by ID and quantity.
R     p122.   10
//It stops showing the result altogether...

Here is my code. Please show me what I did wrong.

import java.util.Scanner;

public class TestPart {
  public static void main(String[] args) {

    // Array of 5 Part objects
    // Part[] part = new Part[5];
    Part[] part = new Part[5];
    part[0] = new Part("p122", "Chain", 48, 12.5);
    part[1] = new Part("p123", "Chain Guard", 73, 22.0);
    part[2] = new Part("p124", "Crank", 400, 11.5);
    part[3] = new Part("p125", "Pedal", 3, 6.5);
    part[4] = new Part("p126", "Handlebar", 123, 9.50);

    ///////// Test Class 2 ////////
    Scanner scanner = new Scanner(System.in);
    System.out.println("Please Enter either S (supply) or R (replenish) followed by ID and quantity.");
    while(!scanner.nextLine().equals("")){

    String sOrR = scanner.next();
    String inputId = scanner.next();
    int amount = scanner.nextInt();
    System.out.println(sOrR);

    for (int i = 0; i < 5; i++) {
        String id = part[i].getID();
        // Find ID in array
        if (id.equals(inputId)) {
            // S or R
            if (sOrR.equals("R")) {
                part[i].replenish(amount);
            } else {

                part[i].supply(amount);

            }
            System.out.println("New Stock-level for " + part[i].getID() + "(" + part[i].getName() + ") is "
                    + part[i].getStockLevel());
        }


    }
    if ((inputId.equals(part[0].getID()) == false) && (inputId.equals(part[1].getID()) == false)
            && (inputId.equals(part[2].getID()) == false) && (inputId.equals(part[3].getID()) == false)
            && (inputId.equals(part[4].getID()) == false)) {
        System.out.println("No part found with ID " + inputId);
    }

    }

    }
}

Yassin Hajaj · Accepted Answer · 2015-10-16 00:47:28Z

3

Replace this line :

while(!scanner.nextLine().equals("")){

With :

while(scanner.hasNext()){

Otherwise you're already jumping to the nextLine() within your test.

answered Oct 16, 2015 at 0:47

Yassin Hajaj

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