java.lang.IndexOutOfBoundsException for ArrayList

Question

I get an java.lang.IndexOutOfBoundsException for this code.

private List<Integer> LoeschenX = new ArrayList<Integer>();
private List<Integer> LoeschenY = new ArrayList<Integer>();

for (int i : LoeschenY) LoeschenX.add(LoeschenY.get(i));

IndexOutOfBoundsException - if the index is out of range (index < 0 || index >= size()) — Keppil
– Keppil, Commented Jan 26, 2014 at 19:26
I think you misunderstood how a for each loop works. i is not the index, it's the int value hold by each Integer object during the iteration. I.e if your list contains 4,-5,12, i will be equals to 4 (iteration 1), -5(iteration 2) and 12(iteration 3). — Alexis C.
– Alexis C., Commented Jan 26, 2014 at 19:26

Christian Tapia · Accepted Answer · 2014-01-26 19:27:16Z

6

When you do

for (int i : LoeschenY)

you are looping over the elements of LoeschenY, not on indexes. You may want to iterate over indexes so you can use get(i):

for (int i = 0; i < LoeschenY.size(); i++) 
    LoeschenX.add(LoeschenY.get(i));

Remember that get(index) will return the value in an specific index.

Edit: You can also try

for (int i : LoeschenY) 
    LoeschenX.add(i);

since i takes the values of the elements of LoeschenY, you will add these values to LoeschenX.

answered Jan 26, 2014 at 19:27

Christian Tapia

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Comments

webuster · Accepted Answer · 2014-01-26 19:28:56Z

1

You seem to be iterating over the elements in the Y array, but the get method actually uses the element as an index the way you're doing it.

Try

for(int i : LoeschenY)
    LoeschenX.add(i);

Or

for(int i = 0; i < LoeschenY.size(); i++)
    LoeschenX.add(LoeschenY.get(i));

answered Jan 26, 2014 at 19:28

webuster

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