Problem with shifting array elements

[holy.water]

Hi,

I need help in arrays.

Let's say i have array that contains DD,GG and JJ.

arr="DD","GG","JJ"

if i want to insert FF in between DD and GG, i would need to shift GG and JJ one space back to have this final array.

arr="DD","FF","GG","JJ"

I have written this code but i am not sure why the final results become this way.

arr="DD","FF","JJ","JJ"

  for (int i = arr.length +1; i > 1; i--) {
        arr[i] = arr[i-1];
       }

Pls advise. Thank You.

[KevinWorkman]

Add a print statement in there that specifies what element you're moving to which index and what the total array looks like each iteration, and you'll see what's going on.

[holy.water]

for (int i = arr.length +1; i > 1; i--) {
        arr[i] = arr[i-1];
System.out.println(arr[i]);
System.out.println(arr[i-1]);
       }

As in this way?

[gcalvin]

for (int i = arr.length +1; i > 1; i--) {
        arr[i] = arr[i-1];
System.out.println(arr[i]);
System.out.println(arr[i-1]);
       }

As in this way?

More like this:

        for (int i = arr.length + 1; i > 1; i--) {
            System.out.println("Moving " + arr[i-1] + " to index " + i);
            arr[i] = arr[i-1];
            System.out.print("Array is now: " + arr[0]);
            for (int j = 1; j < arr.length; j++) {
                 System.out.print(", " + arr[j]);
            }
            System.out.println();
        }

-Gary-

[NRitH]

No, no, no--you do NOT want to manipulate arrays directly like this. Use a java.util.ArrayList instead. To wit:

List<String> list = new ArrayList<String>();
list.add("DD");
list.add("GG");
list.add("JJ");

// now add "HH" at the appropriate index. All other elements will shift as needed.
list.add(1, "HH");

// need it to be a regular array again?
String[] arr = list.toArray();

BTW, if you don't like the way that ArrayList is populated, you can always do a quick & dirty

String[] arr = new String[] { "DD", "GG", "JJ" }
List<String> list = new ArrayList<String>(Arrays.asList(arr));

(Why not just List<String> list = Arrays.asList(arr)? Because Arrays.asList() returns a non-modifiable list.)