How to keep onItemSelected from firing off on a ne

2019-01-01 07:56发布

I've thought of some less than elegant ways to solve this, but I know I must be missing something.

My onItemSelected fires off immediately without any interaction with the user, and this is undesired behavior. I wish for the UI to wait until the user selects something before it does anything.

I even tried setting up the listener in the onResume(), hoping that would help, but it doesn't.

How can I stop this from firing off before the user can touch 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.
    }
}
}

30条回答
浪荡孟婆
2楼-- · 2019-01-01 08:09
if () {        
       spinner.setSelection(0);// No reaction to create spinner !!!
     } else {
        spinner.setSelection(intPosition);
     }


spinner.setOnItemSelectedListener(new AdapterView.OnItemSelectedListener() {

    @Override
    public void onItemSelected(AdapterView<?> parent, View view, int position, long id) {

         if (position > 0) {
           // real selection
         }

      }

    @Override
    public void onNothingSelected(AdapterView<?> parent) {

     }
});
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素衣白纱
3楼-- · 2019-01-01 08:09

I might be answering too late over the post, however I managed to achieve this using Android Data binding library Android Databinding . I created a custom binding to make sure listener is not called until selected item is changed so even if user is selecting same position over and over again event is not fired.

Layout xml file

    <layout>
  <RelativeLayout xmlns:android="http://schemas.android.com/apk/res/android"
 android:layout_width="match_parent"
android:layout_height="wrap_content"
android:layout_marginTop="@dimen/activity_vertical_margin"
xmlns:app="http://schemas.android.com/apk/res-auto">


<Spinner
    android:id="@+id/spinner"
    android:layout_width="150dp"
    android:layout_height="wrap_content"
    android:spinnerMode="dropdown"
    android:layout_below="@id/member_img"
    android:layout_marginTop="@dimen/activity_vertical_margin"
    android:background="@drawable/member_btn"
    android:padding="@dimen/activity_horizontal_margin"
    android:layout_marginStart="@dimen/activity_horizontal_margin"
    android:textColor="@color/colorAccent"
    app:position="@{0}"
    />
 </RelativeLayout>
 </layout>

app:position is where you are passing position to be selected.

Custom binding

  @BindingAdapter(value={ "position"}, requireAll=false)
  public static void setSpinnerAdapter(Spinner spinner, int selected) 
  {

    final int [] selectedposition= new int[1];
    selectedposition[0]=selected;


    // custom adapter or you can set default adapter
        CustomSpinnerAdapter customSpinnerAdapter = new CustomSpinnerAdapter(spinner.getContext(), <arraylist you want to add to spinner>);
        spinner.setAdapter(customSpinnerAdapter);
            spinner.setSelection(selected,false);


    spinner.setOnItemSelectedListener(new AdapterView.OnItemSelectedListener() {
        @Override
        public void onItemSelected(AdapterView<?> parent, View view, int position, long id) {

            String item = parent.getItemAtPosition(position).toString();
        if( position!=selectedposition[0]) {
                        selectedposition[0]=position;
            // do your stuff here
                    }
                }


        @Override
        public void onNothingSelected(AdapterView<?> parent) {

        }
    });
}

You can read more about custom data binding here Android Custom Setter

NOTE

  1. Don't forget to enable databinding in your Gradle file

       android {
     ....
     dataBinding {
     enabled = true
    }
    }
    
  2. Include your layout files in <layout> tags

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ら面具成の殇う
4楼-- · 2019-01-01 08:10
mYear.setOnItemSelectedListener(new OnItemSelectedListener() {
            @Override
            public void onItemSelected(AdapterView<?> parent, View arg1, int item, long arg3) {
                if (mYearSpinnerAdapter.isEnabled(item)) {

                }
            }

            @Override
            public void onNothingSelected(AdapterView<?> parent) {
            }
        });
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几人难应
5楼-- · 2019-01-01 08:12

I would have expected your solution to work -- I though the selection event would not fire if you set the adapter before setting up the listener.

That being said, a simple boolean flag would allow you to detect the rogue first selection event and ignore it.

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春风洒进眼中
6楼-- · 2019-01-01 08:13

After having had the same problem, I came to this solutions using tags. The idea behind it is simple: Whenever the spinner is changed programatically, make sure the tag reflects the selected position. In the listener then you check if the selected position equals the tag. If it does, the spinner selection was changed programatically.

Below is my new "spinner proxy" class:

package com.samplepackage;

import com.samplepackage.R;
import android.widget.Spinner;

public class SpinnerFixed {

    private Spinner mSpinner;

    public SpinnerFixed(View spinner) {
         mSpinner = (Spinner)spinner;
         mSpinner.setTag(R.id.spinner_pos, -2);
    }

    public boolean isUiTriggered() {
         int tag = ((Integer)mSpinner.getTag(R.id.spinner_pos)).intValue();
         int pos = mSpinner.getSelectedItemPosition();
         mSpinner.setTag(R.id.spinner_pos, pos);
         return (tag != -2 && tag != pos);
    }

    public void setSelection(int position) {
        mSpinner.setTag(R.id.spinner_pos, position);
        mSpinner.setSelection(position);
    }

    public void setSelection(int position, boolean animate) {
        mSpinner.setTag(R.id.spinner_pos, position);
        mSpinner.setSelection(position, animate);
    }

    // If you need to proxy more methods, use "Generate Delegate Methods"
    // from the context menu in Eclipse.
}

You will also need an XML file with the tag setup in your Values directory. I named my file spinner_tag.xml, but that's up to you. It looks like this:

<resources xmlns:android="http://schemas.android.com/apk/res/android">
  <item name="spinner_pos" type="id" />
</resources>

Now replace

Spinner myspinner;
...
myspinner = (Spinner)findViewById(R.id.myspinner);

in your code with

SpinnerFixed myspinner;
...
myspinner = new SpinnerFixed(findViewById(R.id.myspinner));

And make your handler somewhat look like this:

myspinner.setOnItemSelectedListener(new AdapterView.OnItemSelectedListener() {

    @Override
    public void onItemSelected(AdapterView<?> parent, View view, int position, long id) {
        if (myspinner.isUiTriggered()) {
            // Code you want to execute only on UI selects of the spinner
        }
    }

    @Override
    public void onNothingSelected(AdapterView<?> parent) {
    }
});

The function isUiTriggered() will return true if and only if the spinner has been changed by the user. Note that this function has a side effect - it will set the tag, so a second call in the same listener call will always return false.

This wrapper will also handle the problem with the listener being called during layout creation.

Have fun, Jens.

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闭嘴吧你
7楼-- · 2019-01-01 08:13

The solution with a boolean flag or a counter didn't help me, 'cause during orientation change onItemSelected() calls "overflew" the flag or the counter.

I subclassed android.widget.Spinner and made tiny additions. The relevant parts are below. This solution worked 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;
}
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