CODEWITHSUNDEEP
javaarraysalgorithmmultidimensional-array
Rayan Saleh
Rayan Saleh

Reputation: 41

How to fix this algorithmic problem with Java arrays?

I have minor problem with part of the algorithm in this code. Here is a description of the task:
User types in a choice between the numbers 0,1,5 or 2.
0 ends the program,
1 prompts the user to add a name and email to the 2d array,
5 prints out all of the names and email pairs the user typed in. And
2 allows the user to search for an exact match by typing in the name and in return the program prints out the email of the name the user is looking for.

Problem is with the choice == 2 algorithm. It seems that there is a problem and it does not work properly. No matter what the user types it will always print out "Match is found!" and return the wrong email.
Any suggestions?

Here is my code:

import java.util.Scanner;
public class Main {
    public static void main(String[] args) {
        Scanner in = new Scanner(System.in);
        String[][] rolodex = new String[257][2];
        System.out.println("Welcome!");
        int choice;
        int p = 0;
        String matchValue;
        boolean isFound = false;
        do {
            System.out.println("Please select an option: ");
            choice = in.nextInt();
            in.nextLine();
            if (choice == 1 && p < rolodex.length) {
                System.out.println("What's the name?");
                rolodex[p][0] = in.nextLine();
                System.out.println("What's the email?");
                rolodex[p][1] = in.nextLine();
                p++;
            } else if (choice == 5) {
                for (int i = 0; i < p; i++) {
                    System.out.println("email: " + rolodex[i][1]);
                    System.out.println("name: " + rolodex[i][0]);
                    System.out.println("--------------------");
                }
            } else if (choice == 2) {
                System.out.println("Type in the name of the email you want: ");
                matchValue = in.nextLine();
                for (int i = 0; i < p; i++) {
                    if (matchValue.equals(rolodex[i][0]) && !isFound) {
                        isFound = true;
                    }
                    if (isFound) {
                        System.out.println("Match Found!");
                        System.out.println(rolodex[i][1]);
                    } else {
                        System.out.println("Match not found!");
                    }
                }
            }
        } while (choice != 0);
        System.out.println("Thank you! Have a nice day!");
    }
}

Upvotes: 0

Views: 103

Answers (2)

user15322354
user15322354

Reputation:

The initializing of the boolean variable and not re-initializing in the following repetitions was causing the problem in your code. Hence, in the block of code I am suggesting below, I have removed the boolean variable altogether. Furthermore, you could try by breaking off from the loop once the correct email match has been identified by the program.

for (int i = 0; i < p; i++) {
    if (matchValue.equals(rolodex[i][0])) {
        System.out.println("Match Found!");
        System.out.println(rolodex[i][1]);
        break;
    } else if (i == (p - 1)) {
        System.out.println("Match not found!");
    }
}

Upvotes: 2

Anuj
Anuj

Reputation: 1665

You need to reset the value of isFound after it has been set to true. You have not done so, hence the wrong output.

if (isFound) {
    System.out.println("Match Found!");
    System.out.println(rolodex[i][1]);

    //Add this to your code
    isFound = false;
}

There is another problem with your search. You have to stop the loop once the match has been found. You have not done so.

I do suggest you try to do it on your own. You should also check @Ayyan Tahzib answer as it contains a hint on correcting this problem of your searching procedure.

If you face any problems, do comment. I will be happy to help you.

Upvotes: 2

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