For some reason loop doesn't print out correct array values

Question

I'm having some trouble getting the correct output when printing an array. Essentially what I'm trying to do is set up an array in the main method, then send that array to another method that would print out something like this:

   89   12   33   7   72   42   76   49
   69   85   61   23

With it being 3 spaces to the right and starting a new print line after the 8th number. Seems easy enough but I get something like this instead.

   89
   69   85   61   23

It doesn't print out the values between position 1 and 7 for some reason. This is what I have.

public class Test
{
    public static void main (String [] args)
    {
        int [] myInches = {89,12,33,7,72,42,76,49,69,85,61,23};
        printArrayValues(myInches);
    }

    public static void printArrayValues(int [] myInchesParam) {
        for (int i = 0; i < 8; i++) {
            System.out.print("   " + myInchesParam[i]);
            System.out.println();
            for (i = 8; i < 12; i++) {
                System.out.print("   " + myInchesParam[i]);
            }
        }
    }
}

Should I use a do-while instead? Or can I still do it with a for loop and I'm just doing it wrong?

Your 8-11 loop is inside your 0-7 loop, and using the same loop variable. — khelwood
– khelwood, Commented Apr 11, 2019 at 21:07
Use } to close off your first loop before your second one starts. — Dawood ibn Kareem
– Dawood ibn Kareem, Commented Apr 11, 2019 at 21:08
move the inner for loop to after the first one. Alternatively, get rid of the inner for loop, have the outer one loop through all the values and have System.out.println only if i % 8 === 7. — p.s.w.g
– p.s.w.g, Commented Apr 11, 2019 at 21:08
Use another variable in second for loop, i is already defined in first loop — Marios Nikolaou
– Marios Nikolaou, Commented Apr 11, 2019 at 21:13

brandonx · Accepted Answer · 2019-04-11 21:12:55Z

1

There are many ways to solve this but one would be using the modulo operator to check if 8 entries have already been printed. You add 1 to i because your array is 0 indexed.

   for (int i = 0; i < myInchesParam.length; i++) {      
        System.out.print(myInchesParam[i] + "   ");
        if((i + 1) % 8 == 0) {
            System.out.println();
        }
   }

EDIT: The benefit of this method is that it works for any array length. Some of the other suggestions will not.

answered Apr 11, 2019 at 21:12

brandonx

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Comments

Filip Eriksson · Accepted Answer · 2019-04-11 21:15:50Z

1

Well, what is happening is that in the loop i starts as 0, then when it reaches the second loop you set i to 8, and thus the condition i < 8 is no longer valid. Easiest fix would be to not nest your loops but have

    for (int i = 0; i < 8; i++) {
        System.out.print("   " + myInchesParam[i]);
    }
    System.out.println();
    for (i = 8; i < 12; i++) {
            System.out.print("   " + myInchesParam[i]);
    }

instead. Even nicer is probably

    for (int i = 0; i < 12; i++) {
        System.out.print("   " + myInchesParam[i]);
        if(i==7) {
          System.out.println();
        }
    }

answered Apr 11, 2019 at 21:15

Filip Eriksson

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Comments

Samuel Philipp · Accepted Answer · 2019-04-11 21:21:54Z

The problem is you that you are using the same variable in two nested for loops. This will cause the outer array to stop after the first iteration and print only the values in the second line.

Just use one loop and print a new line if i > 0 && i % 8 == 0:

public static void printArrayValues(int[] myInchesParam) {
    for (int i = 0; i < myInchesParam.length; i++) {
        if (i > 0 && i % 8 == 0)
            System.out.println();
        System.out.print("   " + myInchesParam[i]);
    }
}

Alternatively you can just use i % 8 === 7 to insert a new line afterwards:

public static void printArrayValues(int[] myInchesParam) {
    for (int i = 0; i < myInchesParam.length; i++) {
        System.out.print("   " + myInchesParam[i]);
        if (i % 8 == 7)
            System.out.println();
    }
}

But you could have a trailing new line in some cases with this last solution.

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