Android Spinner - onItemSelected / setOnItemSelectedListener未触发

Question

This is driving me nuts since it's something I've done before but can't figure out why it isn't working now...

I've got a menu button, implemented in the usual way via a menu.xml file and the onOptionsItemSelected method with a switch in it, that creates and displays a spinner.

I've added the setOnItemSelectedListener , but it never seems to trigger. The spinner appears, I pick an option or back out, neither onItemSelected or onNothingSelected are called.

Here is all the code between the "case" and "return true" of the menu-button-handling switch statement. ( topThis is a variable referring to the context of the activity - works fine for all other toasts in the app)

String[] widgetModes = {"Mode 1", "Mode2"};
ArrayAdapter<String> widgetModeAdapter = new ArrayAdapter<String> (this, android.R.layout.simple_spinner_item, widgetModes);
widgetModeAdapter.setDropDownViewResource(android.R.layout.simple_spinner_dropdown_item);

Spinner widgetModeSpinner = new Spinner(this);
widgetModeSpinner.setAdapter(widgetModeAdapter);
widgetModeSpinner.setPrompt("Choose Widget Mode");

widgetModeSpinner.setOnItemSelectedListener(new OnItemSelectedListener() 
{
    @Override
    public void onItemSelected(AdapterView<?> parentView, View selectedItemView, int position, long id) 
    {
        Toast.makeText(topThis, "derp", Toast.LENGTH_LONG).show();
    }

    @Override
    public void onNothingSelected(AdapterView<?> parentView) 
    {
        Toast.makeText(topThis, "herf", Toast.LENGTH_LONG).show();
    }
});

widgetModeSpinner.performClick();

Any ideas? I vaguely suspect that the fact I'm creating the Spinner programmatically is the problem...

Answer 1

I had the similar problem when I was implementing a spinner, I resolved it by getting the parent View and set Adapter-

spinner1 =(Spinner)findViewById(R.id.spinner1);
spinner1.setAdapter(BindSpinner("ProgramMaster",cols,null,true,""));
spinner1.setOnItemSelectedListener(new OnItemSelectedListener() 
{
protected Adapter initializedAdapter=null;
    @Override
    public void onItemSelected(AdapterView<?> parentView, View selectedItemView, int position, long id) 
    {
        if(initializedAdapter !=parentView.getAdapter() ) {
            initializedAdapter = parentView.getAdapter();
           return;
        }

        String selected = parentView.getItemAtPosition(position).toString();

        if(abc.equals("Select") && !selected.equals("Select"))
        {
            do something
        }

        else 
        {
            Do something
        }
        textQualification=selected;
        SearchUpdated("Qualification");
    }

    @Override
    public void onNothingSelected(AdapterView<?> parentView) {
        // your code here
    }
});

Answer 2

Remember that you can't re-select the same spinner item, it always sets the first item as selected if you are not adding some custom code to handle the spinner selection.

For the Toast not showing, I would suggest to always use the "MyActivity.this" as your context when creating a Toast inside a listener interface like this:

spinner.setOnItemSelectedListener(new AdapterView.OnItemSelectedListener() {
        /**
         * Called when a new item is selected (in the Spinner)
         */
         public void onItemSelected(AdapterView<?> parent, View view, 
                    int pos, long id) {
                // An spinnerItem was selected. You can retrieve the selected item using
                // parent.getItemAtPosition(pos)

                Toast.makeText(MyActivity.this, "Hello Toast",Toast.LENGTH_SHORT).show();

            }

            public void onNothingSelected(AdapterView<?> parent) {
                // Do nothing, just another required interface callback
            }

    }); // (optional)

And the .show() at the end is easy to forget sometimes;)

Answer 3

实际上，如果您的微调器可见性设置为已消失 ，那么当您调用performclick（）方法时它将触发它的单击，但它不会触发其setOnItemSelectedListener，因此您需要更改可见性然后它将起作用

Answer 4

I know the question is a bit old, but in case you are waiting for a AsyncTask callback, make sure that you let your adapter know of the data changes by calling notifyDataSetChanged() on the callback thread!

@Override
public void onPostExecute(String result) {
   ///do something with your data  
   spinnerArrayAdapter.notifyDataSetChanged();
}