Android：如何在单选模式ListView中选择更改时收到通知？

Question

I want my ListView to highlight the selected item until selection changes. Also, I want to be notified when selection changes.

In order to accomplish the first task, I call list.setChoiceMode(ListView.CHOICE_MODE_SINGLE) .

I'm not sure how to accomplish the second. When a list item is clicked, my OnItemSelectedListener is never notified, and the OnItemClickListener is insufficient because by the time the OnItemClick event occurs, my ListView's checkedItem has been modified, so I cannot distinguish if the click event resulted in a selection change (it is possible/likely that the clicked item was already selected).

One option would be to store the currently checked index in a member variable, which I could use to determine if the click event corresponds to a selection change. But this ugly and So, for this choice mode, certainly there is a way to do this with the provided listeners?

public class Temp extends Activity implements OnItemClickListener, OnItemSelectedListener
{
    ListView mView;

    @Override
    public void onCreate(Bundle savedInstanceState) 
    {
        super.onCreate(savedInstanceState);

        List<String> strings = new ArrayList<String>();
        strings.add("1");
        strings.add("2");
        strings.add("3");
        strings.add("4");
        strings.add("5");


        mView = new ListView(this);
        mView.setChoiceMode(ListView.CHOICE_MODE_SINGLE);
        mView.setAdapter(new ArrayAdapter<String>(this, android.R.layout.simple_list_item_activated_1, strings));
        mView.setItemChecked(0, true);

        mView.setOnItemClickListener(this);
        mView.setOnItemSelectedListener(this);

        setContentView(mView);
    }

    @Override
    public void onItemSelected(AdapterView<?> parent, View view, int position, long id)
    {
        //this never gets called
        Log.e("item selected", ""+position);
    }

    @Override
    public void onNothingSelected(AdapterView<?> parent)
    {
        Log.e("nothing seleted", "");
    }

    @Override
    public void onItemClick(AdapterView<?> parent, View view, int position, long id)
    {
                //by the time this occurs, position == mView.getCheckedItemPosition()
        Log.e("item clicked", ""+position);
    }
}

Answer 1

When a list item is clicked, my OnItemSelectedListener is never notified.

The OnItemSelectedListener is only called by a ListView when you use a trackball, keyboard navigation, or use another type of non-touch navigation. It does not correlate to the choice mode.

One option would be to store the currently checked index in a member variable, which I could use to determine if the click event corresponds to a selection change.

This is the best option. It only involves one extra int and an if-statement.