How to shift element in an Arraylist to the right in java

Question

So I am trying to create a method that shifts all of the elements in an arraylist to the right and the last element will become the first element. When I run the code, I am told I have an out of bounds error. Here is what I have so far:

public void shiftRight() 
{
    //make temp variable to hold last element
    int temp = listValues.get(listValues.size()-1); 

    //make a loop to run through the array list
    for(int i = listValues.size()-1; i >= 0; i--)
    {
        //set the last element to the value of the 2nd to last element
        listValues.set(listValues.get(i),listValues.get(i-1)); 

        //set the first element to be the last element
        listValues.set(0, temp); 
    }

}

This may help you..

Ramiz Wachtler
– Ramiz Wachtler

2015-09-03 23:57:23 +00:00
Commented Sep 3, 2015 at 23:57 — Ramiz Wachtler
– Ramiz Wachtler, Commented Sep 3, 2015 at 23:57
So you want to do a circular rotation of the elements?

Nayuki
– Nayuki

2015-09-04 00:29:37 +00:00
Commented Sep 4, 2015 at 0:29 — Nayuki
– Nayuki, Commented Sep 4, 2015 at 0:29

user949300 · Accepted Answer · 2015-09-04 00:13:47Z

12

Maybe this is an exercise you are working on, but the ArrayList.add(int index,E element) method does almost what you want.

"Inserts the specified element at the specified position in this list. Shifts the element currently at that position (if any) and any subsequent elements to the right (adds one to their indices)." (italics added)

So just add the last element in the list at position 0. And delete it from the end.

answered Sep 4, 2015 at 0:13

user949300

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Comments

logee · Accepted Answer · 2015-09-04 00:06:58Z

A few problems here:

Your for loop condition needs to exclude the zeroth element so it should be i > 0 otherwise you'll get to the point where you want to put element at position -1 to position 0 resulting in out of bounds error.
Setting the first element to be the last should be outside the loop.

listValues.set takes in an index in the list as the first parameter, you are giving it the object in the list

public void shiftRight() 
{
    //make temp variable to hold last element
    int temp = listValues.get(listValues.size()-1); 

    //make a loop to run through the array list
    for(int i = listValues.size()-1; i > 0; i--)
    {
        //set the last element to the value of the 2nd to last element
        listValues.set(i,listValues.get(i-1)); 
    }
    //set the first element to be the last element
    listValues.set(0, temp);     
}

Reza · Accepted Answer · 2020-10-14 14:05:48Z

2

The easiest and shortest solution : (if you don't have concurrent use of list - Because in concurrent use and iterating on it, the list size should not change, otherwise you get ConcurrentModificationException)

public void shiftOneToRight() {
    
    listValues.add(0, listValues.remove(listValues.size() - 1));
    
}

answered Oct 14, 2020 at 14:05

Reza

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Comments

Jay · Accepted Answer · 2020-11-26 12:45:43Z

2

Here is the simplest solution

Collections.rotate(list, rotationPosition);

answered Nov 26, 2020 at 12:45

Jay

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Comments

Dan Alboteanu · Accepted Answer · 2017-01-26 16:07:28Z

0

my code to put a number in the right place in a List

            int nr = 5;  // just a test number
            boolean foundPlace = false;

            for(int i = 0; i < integerList.size(); i++){

                if(nr <= integerList.get(i)){
                    integerList.add(i,nr);
                    foundPlace = true;
                    break;
                }

            }
            if (!foundPlace)
                integerList.add(integerList.size(), nr);

as the guy above said, "integerList.add(element)" inserts the specified element at the specified position in this list. Shifts the element currently...

answered Jan 26, 2017 at 16:07

Dan Alboteanu

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Comments

PankajChandankar · Accepted Answer · 2020-06-23 06:45:12Z

0

input array list: locationMap

shift LHS elements from idxStart in circular way

shifted output list: extendedList

// make extended list to behave like circular
List<String> extendedList = new ArrayList<>();
for (int i = idxStart; i < locationMap.size(); i++) { // current to end
    extendedList.add(locationMap.get(i));
}
for (int i = 0; i < idxStart; i++) { // 0 to current
    extendedList.add(locationMap.get(i));
}

answered Jun 23, 2020 at 6:45

PankajChandankar

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