Infinite Loop in Java 2d array program

Question

The program is supposed to end and give the amount of correct answers once the last question is answered. Instead the program goes back to the initial question in the loop. "What is the capital of Alabama"

package exercise09_17;
import java.util.Scanner;

public class exercise09_17 {

    static Scanner input = new Scanner(System.in).useDelimiter("\r\n"); 
    public static void main(String[] args) {
        int correctAnswer = 0;
        String [][] grid = {
                {"Alabama", "California", "Delaware", "Florida", "Georgia",
                "Hawaii", "Idaho", "Kansas", "Lousiana", "Maryland", "New Mexico", "Oregon",
                "Pennsylvania", "Rhode Island", "South Carolina", "Texas", "Utah", "Virgina",
                "West Virginia"},
                {"Montgomery", "Sacramento", "Dover", "Tallahassee", "Atlanta",
                "Honolulu", "Boise", "Topeka", "Baton Rouge", "Annapolis", "San Jose", "Salem",
                "Harrisburg", "Providence", "Columbia", "Austin", "Salt Lake City", "Richmond",
                "Charleston"}};

        for(int i = 0; i< grid.length; i++){

            for(int k = 0; k < grid[i].length; k++ ){
                System.out.println("What is the capital of " + grid[0][k] + "?");
                String capital = input.next();
                String answer = grid[1][k];


                if(capital.equalsIgnoreCase(answer)){
                correctAnswer ++;   
                System.out.println("Your answer is correct");
                }
                else
                    System.out.println("The correct answer should be " + answer);
            }

        }
        System.out.println("The correct count is " + correctAnswer);
    }
}

That's not infinite. It's merely repeating itself because of the nesting of the loops. — Makoto
– Makoto, Commented Feb 16, 2014 at 18:35

torquestomp · Accepted Answer · 2014-02-16 18:35:13Z

1

It's not infinite. It just goes twice:

for(int i = 0; i< grid.length; i++){

There's no need for this i variable here, and hence the entire outer-loop as well, since you use both sub-arrays, grid[0] and grid[1] on the first go-through

answered Feb 16, 2014 at 18:35

torquestomp

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Comments

Blue Ice · Accepted Answer · 2014-02-16 18:35:29Z

1

Try removing the extraneous for loop:

public class exercise09_17 {

    static Scanner input = new Scanner(System.in).useDelimiter("\r\n"); 
    public static void main(String[] args) {
        int correctAnswer = 0;
        String [][] grid = {
                {"Alabama", "California", "Delaware", "Florida", "Georgia",
                "Hawaii", "Idaho", "Kansas", "Lousiana", "Maryland", "New Mexico", "Oregon",
                "Pennsylvania", "Rhode Island", "South Carolina", "Texas", "Utah", "Virgina",
                "West Virginia"},
                {"Montgomery", "Sacramento", "Dover", "Tallahassee", "Atlanta",
                "Honolulu", "Boise", "Topeka", "Baton Rouge", "Annapolis", "San Jose", "Salem",
                "Harrisburg", "Providence", "Columbia", "Austin", "Salt Lake City", "Richmond",
                "Charleston"}};



        for(int k = 0; k < grid[0].length; k++ ){
            System.out.println("What is the capital of " + grid[0][k] + "?");
            String capital = input.next();
            String answer = grid[1][k];


            if(capital.equalsIgnoreCase(answer)){
                correctAnswer ++;   
                System.out.println("Your answer is correct");
            } else
                System.out.println("The correct answer should be " + answer);
        }

        System.out.println("The correct count is " + correctAnswer);
    }
}

answered Feb 16, 2014 at 18:35

Blue Ice

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1 Comment

torquestomp Over a year ago

Your code snippet won't compile because there is no i variable, the for loop should have k < grid[0].length

Aniket Thakur · Accepted Answer · 2014-02-16 18:35:34Z

0

Change

System.out.println("What is the capital of " + grid[0][k] + "?");

to

System.out.println("What is the capital of " + grid[i][k] + "?");

Since you are using grid[0][k] after going through all k iterations it will come back for another k iteration on same i=0 till i<grid.length

answered Feb 16, 2014 at 18:35

Aniket Thakur

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Comments

Brian · Accepted Answer · 2014-02-16 18:42:52Z

0

You do not have an infinite loop, but you will repeat the process as many times as the grid length. Basically, you do not need the outer for loop. Remove the loop

for(int i = 0; i < grid.length; i++)

and instead of

for(int k = 0; k < grid[i].length; k++ ){

change to

for(int k = 0; k < grid[0].length; k++ ){

answered Feb 16, 2014 at 18:42

Brian

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