Question

I have a listview connected to a custom array adapter. This list shows information received by a TCP connection which changes the dataSet…

I am able to sort the listview with sort (Comparator<? super T> comparator), but when the dataSet is changed, the listview is no more sorted…

I can use sort () every time the dataSet is changed, but I think this is not the best option…

How can I do that? Any suggestions?

EDIT

I am having problems in implementing the solutions presented…

MyComparatorB.java

public class MyComparatorB implements Comparator<DeviceB> {

private byte orderType;

public MyComparatorB(byte type) {

    this.orderType = type;

}

public int compare(DeviceB lhs, DeviceB rhs) {

    int res = 0;
    if (orderType == SortType.ALPHA) {
            res = (lhs.getName()).compareTo(rhs.getName());
        }
        else if (orderType == SortType.LAST_ACT) {
            res = (rhs.getTime().getTime()).compareTo(lhs.getTime().getTime());
        }
        return res;
    }

}

Snippet of my customArrayAdapter.java

    @Override
public void notifyDataSetChanged() {
    super.notifyDataSetChanged();
}


//-----------Order the content of the arrayAdapter------------//
public void sort(byte sortType) {

    super.sort(new MyComparatorB(sortType));
    notifyDataSetChanged();
}

In my MyActivity.java

myDevAdapter.sort(SortType.ALPHA);

When I am debugging, the method super.sort(new MyComparatorB(sortType)); is called and the constructor of MyComparatorB is called too. But the method compare(DeviceB lhs, DeviceB rhs) is never called and my arrayList is not sorted…
What I am doing wrong?

Answer 1

I guess you need to override notifyDataSetChanged method in your adapter and perform sorting right before calling its super. See below:

@Override
public void notifyDataSetChanged() {
    //do your sorting here

    super.notifyDataSetChanged();
}

Doing so will sort the list whenever you call notifyDataSetChanged method to refresh list items. Otherwise, feed a sorted List/array to your adapter.

---

Or more preferably, use the sort method available in your adapter to get the job done.

adapter.sort(new Comparator<String>() {
    @Override
    public int compare(String lhs, String rhs) {
        return lhs.compareTo(rhs);   //or whatever your sorting algorithm
    }
});