ArrayList replace element if exists at a given index?

问题

How to replace element if exists in an ArrayList at a given index?

回答1:

  arrayList.set(index i,String replaceElement);

回答2:

If you're going to be requiring different set functionaltiy, I'd advise extending ArrayList with your own class. This way, you won't have to define your behavior in more than one place.

// You can come up with a more appropriate name
public class SizeGenerousArrayList<E> extends java.util.ArrayList<E> {

    @Override
    public E set(int index, E element) {
        this.ensureCapacity(index+1); // make sure we have room to set at index
        return super.set(index,element); // now go as normal
    }

    // all other methods aren't defined, so they use ArrayList's version by default

}

回答3:

An element is over-written if it already exists at an index, that is the default behaviour: Javadoc.

Or am I missing your point completely?

回答4:

Just add a break after your remove() statement

来源：https://stackoverflow.com/questions/5617175/arraylist-replace-element-if-exists-at-a-given-index