I came up with some less elegant solutions to this problem, but I knew I had to leave out something.
My onitem selected will trigger immediately without any interaction with the user, which is not a welcome behavior. I want the UI to wait until the user chooses to do anything.
I even tried to set up a listener on onResume(), which I hope will help, but it wasn't.
How can I stop this operation before the user touches the control?
public class CMSHome extends Activity { private Spinner spinner; @Override public void onCreate(Bundle savedInstanceState) { super.onCreate(savedInstanceState); setContentView(R.layout.main); // Heres my spinner /////////////////////////////////////////// spinner = (Spinner) findViewById(R.id.spinner); ArrayAdapter<CharSequence> adapter = ArrayAdapter.createFromResource( this, R.array.pm_list, android.R.layout.simple_spinner_item); adapter.setDropDownViewResource(android.R.layout.simple_spinner_dropdown_item); spinner.setAdapter(adapter); }; public void onResume() { super.onResume(); spinner.setOnItemSelectedListener(new MyOnItemSelectedListener()); } public class MyOnItemSelectedListener implements OnItemSelectedListener { public void onItemSelected(AdapterView<?> parent, View view, int pos, long id) { Intent i = new Intent(CMSHome.this, ListProjects.class); i.putExtra("bEmpID", parent.getItemAtPosition(pos).toString()); startActivity(i); Toast.makeText(parent.getContext(), "The pm is " + parent.getItemAtPosition(pos).toString(), Toast.LENGTH_LONG).show(); } public void onNothingSelected(AdapterView parent) { // Do nothing. } } }
#1 building
A solution with Boolean flags or counters won't help me because onItemSelected() calls the "overflow" flag or counter when the direction changes.
I subclass android.widget.Spinner and make some minor additions. The relevant parts are as follows. This solution works for me.
private void setHandleOnItemSelected() { final StackTraceElement [] elements = Thread.currentThread().getStackTrace(); for (int index = 1; index < elements.length; index++) { handleOnItemSelected = elements[index].toString().indexOf("PerformClick") != -1; //$NON-NLS-1$ if (handleOnItemSelected) { break; } } } @Override public void setSelection(int position, boolean animate) { super.setSelection(position, animate); setHandleOnItemSelected(); } @Override public void setSelection(int position) { super.setSelection(position); setHandleOnItemSelected(); } public boolean shouldHandleOnItemSelected() { return handleOnItemSelected; }
#2 building
I created a small utility method to change the Spinner selection without notifying the user:
private void setSpinnerSelectionWithoutCallingListener(final Spinner spinner, final int selection) { final OnItemSelectedListener l = spinner.getOnItemSelectedListener(); spinner.setOnItemSelectedListener(null); spinner.post(new Runnable() { @Override public void run() { spinner.setSelection(selection); spinner.post(new Runnable() { @Override public void run() { spinner.setOnItemSelectedListener(l); } }); } }); }
It disables the listener, changes the selection, and then re enables the listener.
The trick is that the call is asynchronous with the UI thread, so you have to do this in consecutive handler posts.
#3 building
I am in a similar situation and I have a simple solution to work for me.
It seems that the methods setSelection(int position) and setSelected(int position, boolean animate) have different internal implementations.
When you use the second method setSelected(int position, boolean animate) with the false animate flag, you get the selection without triggering the onItemSelected listener.
#4 building
I found a more elegant solution. It involves calculating the number of times the ArrayAdapter (in your case, the "adapter") is called. Suppose you have a spinner and you call:
int iCountAdapterCalls = 0; ArrayAdapter<CharSequence> adapter = ArrayAdapter.createFromResource( this, R.array.pm_list, android.R.layout.simple_spinner_item); adapter.setDropDownViewResource(android.R.layout.simple_spinner_dropdown_item); spinner.setAdapter(adapter);
Declare an int counter after onCreate, and then place an "if" condition inside the onItemSelected() method to check how many times the atapter has been called. In your case, you only need to call once:
if(iCountAdapterCalls < 1) { iCountAdapterCalls++; //This section executes in onCreate, during the initialization } else { //This section corresponds to user clicks, after the initialization }
#5 building
Unfortunately, it seems that two of the most common recommended solutions to this problem are to calculate callback events and to publish Runnable so that callbacks can be set later, such as when accessibility options are enabled. This is a helper class to solve these problems. Further expansion is in the comment block.
import android.view.View; import android.widget.AdapterView; import android.widget.AdapterView.OnItemSelectedListener; import android.widget.Spinner; import android.widget.SpinnerAdapter; /** * Spinner Helper class that works around some common issues * with the stock Android Spinner * * A Spinner will normally call it's OnItemSelectedListener * when you use setSelection(...) in your initialization code. * This is usually unwanted behavior, and a common work-around * is to use spinner.post(...) with a Runnable to assign the * OnItemSelectedListener after layout. * * If you do not call setSelection(...) manually, the callback * may be called with the first item in the adapter you have * set. The common work-around for that is to count callbacks. * * While these workarounds usually *seem* to work, the callback * may still be called repeatedly for other reasons while the * selection hasn't actually changed. This will happen for * example, if the user has accessibility options enabled - * which is more common than you might think as several apps * use this for different purposes, like detecting which * notifications are active. * * Ideally, your OnItemSelectedListener callback should be * coded defensively so that no problem would occur even * if the callback was called repeatedly with the same values * without any user interaction, so no workarounds are needed. * * This class does that for you. It keeps track of the values * you have set with the setSelection(...) methods, and * proxies the OnItemSelectedListener callback so your callback * only gets called if the selected item's position differs * from the one you have set by code, or the first item if you * did not set it. * * This also means that if the user actually clicks the item * that was previously selected by code (or the first item * if you didn't set a selection by code), the callback will * not fire. * * To implement, replace current occurrences of: * * Spinner spinner = * (Spinner)findViewById(R.id.xxx); * * with: * * SpinnerHelper spinner = * new SpinnerHelper(findViewById(R.id.xxx)) * * SpinnerHelper proxies the (my) most used calls to Spinner * but not all of them. Should a method not be available, use: * * spinner.getSpinner().someMethod(...) * * Or just add the proxy method yourself :) * * (Quickly) Tested on devices from 2.3.6 through 4.2.2 * * @author Jorrit "Chainfire" Jongma * @license WTFPL (do whatever you want with this, nobody cares) */ public class SpinnerHelper implements OnItemSelectedListener { private final Spinner spinner; private int lastPosition = -1; private OnItemSelectedListener proxiedItemSelectedListener = null; public SpinnerHelper(Object spinner) { this.spinner = (spinner != null) ? (Spinner)spinner : null; } public Spinner getSpinner() { return spinner; } public void setSelection(int position) { lastPosition = Math.max(-1, position); spinner.setSelection(position); } public void setSelection(int position, boolean animate) { lastPosition = Math.max(-1, position); spinner.setSelection(position, animate); } public void setOnItemSelectedListener(OnItemSelectedListener listener) { proxiedItemSelectedListener = listener; spinner.setOnItemSelectedListener(listener == null ? null : this); } public void onItemSelected(AdapterView<?> parent, View view, int position, long id) { if (position != lastPosition) { lastPosition = position; if (proxiedItemSelectedListener != null) { proxiedItemSelectedListener.onItemSelected( parent, view, position, id ); } } } public void onNothingSelected(AdapterView<?> parent) { if (-1 != lastPosition) { lastPosition = -1; if (proxiedItemSelectedListener != null) { proxiedItemSelectedListener.onNothingSelected( parent ); } } } public void setAdapter(SpinnerAdapter adapter) { if (adapter.getCount() > 0) { lastPosition = 0; } spinner.setAdapter(adapter); } public SpinnerAdapter getAdapter() { return spinner.getAdapter(); } public int getCount() { return spinner.getCount(); } public Object getItemAtPosition(int position) { return spinner.getItemAtPosition(position); } public long getItemIdAtPosition(int position) { return spinner.getItemIdAtPosition(position); } public Object getSelectedItem() { return spinner.getSelectedItem(); } public long getSelectedItemId() { return spinner.getSelectedItemId(); } public int getSelectedItemPosition() { return spinner.getSelectedItemPosition(); } public void setEnabled(boolean enabled) { spinner.setEnabled(enabled); } public boolean isEnabled() { return spinner.isEnabled(); } }