Java - Exception in thread “main” java.util.ConcurrentModificationException

Question

Is there any way I can modify the HashMap values of a particular key while iterating over it?

A sample program is given below:

public st         


        

Answer 1

If you want to add to the original ArrayList, then iterate through it on your own:

final ArrayList arr = hm.get(1);
final int size = arr.size();

// this will add size number of "hello" strings to ArrayList arr
for(int i = 0; i < size; ++i){
    // you don't appear to ever use this value
    final String s = arr.get(i);

    // do something to arr
    arr.add("hello");
}