CODEWITHSUNDEEP
javaarraysdebugging
Scanner
Scanner

Reputation: 73

Process of how do I spot the errors in this buggy code?

I have this code:

When I launch it, I am able to get numbers i = 0 to i = 10. However I know this is not the objective of the code as the objective is to reach into the Scanner. But the scanner does not seem to work? Am I making an error importing a file or is this to do with the code? I'm noob.

package buggyProgram;

import java.util.Scanner;

public class BuggyProgram {

  /**
   * The main method of the program. This is where it all starts.
   */
  public static void main(String[] args) {
  String[] saNames = new String[5];
  String[] saNumbers = new String[5];

  Scanner scIn = new Scanner(System.in);
    for (int i = 0; i <= 4; i++) {
        System.out.print("Enter name: ");
        saNames[i] = scIn.nextLine();

        System.out.print("Enter number: ");
        saNumbers[i] = scIn.nextLine();
    }

    System.out.println();

    for (int i = 1; i < 4; i++) {
        System.out.println("The number of " + saNames[i] + " is "
                + saNames[i] + ".");
    }
  }
}

Upvotes: 2

Views: 251

Answers (3)

MarkusAtCvlabDotDe
MarkusAtCvlabDotDe

Reputation: 1042

I can confirm, that your code works, as long as you change your final output:

    String[] saNames = new String[5];
    String[] saNumbers = new String[5];

    Scanner scIn = new Scanner(System.in);
    for (int i = 0; i <= 4; i++) {
        System.out.print("Enter name: ");
        saNames[i] = scIn.nextLine();

        System.out.print("Enter number: ");
        saNumbers[i] = scIn.nextLine();
    }

    System.out.println();

    for (int i = 1; i < 4; i++) {
        System.out.println("The number of " + saNames[i] + " is "
                + saNumbers[i] + ".");
    }

Upvotes: 0

Morgen
Morgen

Reputation: 1038

One of the first things you can do to make it easier to debug is to make the input fixed between runs. If you change Scanner scIn = new Scanner(System.in); to this:

Scanner scIn = new Scanner(new BufferedReader(new FileReader("some-file.txt")));

Assuming that some-file.txt is populated with the appropriate input, then you can run the program multiple times without having to manually re-enter the input. In addition, the input is fixed, so comparing the output of different runs becomes more useful.

Upvotes: 0

Elliott Frisch
Elliott Frisch

Reputation: 201447

Java arrays start at 0 (not 1), and you're printing the same array element twice (in your second for-loop). Finally, you could always use a debugger to help you determine where things are no longer working as you expect.

// for (int i = 1; i < 4; i++) {
for (int i = 0; i <= 4; i++) { // <-- to match your first loop.
    System.out.println("The number of " + saNames[i] + " is "
            + saNumbers[i] + ".");
}

You might also use formatted output (the formatter syntax) like

for (int i = 0; i <= 4; i++) {
    System.out.printf("The number of %s is %s.%n", saNames[i], saNumbers[i]);
}

Upvotes: 1

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