我想过一些不那么优雅的方法来解决这个问题,但我知道我一定遗漏了什么。

我的onItemSelected立即启动,没有与用户进行任何交互,这是不希望的行为。我希望UI能够等到用户选择某样东西后再执行任何操作。

我甚至尝试在onResume()中设置监听器,希望能有所帮助,但它没有。

我怎样才能阻止它在用户可以触摸控件之前发射?

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.
    }
}
}

当前回答

不幸的是,解决这个问题的两个最常见的建议解决方案,即统计回调发生次数和发布Runnable以在稍后设置回调,在启用可访问性选项时都可能失败。下面是一个帮助类,它可以解决这些问题。进一步的解释在评论区。

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(); }
}

其他回答

我希望您的解决方案能够工作——我认为如果在设置侦听器之前设置适配器,则选择事件不会触发。

也就是说,一个简单的布尔标志将允许您检测到恶意的第一次选择事件并忽略它。

我也遇到过类似的情况,我有一个简单的解决办法。

看起来setSelection(int position)和setSelected(int position, boolean animate)方法有不同的内部实现。

当你使用第二个方法setSelected(int position, boolean animate)并带有false animate标志时,你得到的选择不会触发onItemSelected监听器。

这也不是一个优雅的解决方案。事实上,这有点像鲁布-戈德堡,但似乎很有效。通过扩展数组适配器并覆盖其getDropDownView,我确保旋转器至少被使用过一次。在新的getDropDownView方法中,我有一个布尔标志,被设置为显示下拉菜单至少被使用过一次。在设置标志之前,我会忽略对侦听器的调用。

MainActivity.onCreate ():

ActionBar ab = getActionBar();
ab.setDisplayShowTitleEnabled(false);
ab.setNavigationMode(ActionBar.NAVIGATION_MODE_LIST);
ab.setListNavigationCallbacks(null, null);

ArrayList<String> abList = new ArrayList<String>();
abList.add("line 1");
...

ArAd  abAdapt = new ArAd (this
   , android.R.layout.simple_list_item_1
   , android.R.id.text1, abList);
ab.setListNavigationCallbacks(abAdapt, MainActivity.this);

覆盖的数组适配器:

private static boolean viewed = false;
private class ArAd extends ArrayAdapter<String> {
    private ArAd(Activity a
            , int layoutId, int resId, ArrayList<String> list) {
        super(a, layoutId, resId, list);
        viewed = false;
    }
    @Override
    public View getDropDownView(int position, View convertView,
            ViewGroup parent) {
        viewed = true;
        return super.getDropDownView(position, convertView, parent);
    }
}

修改监听器:

@Override
public boolean onNavigationItemSelected(
   int itemPosition, long itemId) {
   if (viewed) {
     ...
   }
   return false;
}

我找到了更优雅的解决方法。它包括计算ArrayAdapter(在您的例子中是“适配器”)被调用的次数。假设你有一个转轮,你调用:

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);

在onCreate之后声明一个int计数器,然后在onItemSelected()方法内部放置一个“if”条件来检查atapter被调用了多少次。在你的例子中,你只调用了一次:

if(iCountAdapterCalls < 1)
{
  iCountAdapterCalls++;
  //This section executes in onCreate, during the initialization
}
else
{
  //This section corresponds to user clicks, after the initialization
}

如果你在代码中进行选择,就会发生这种情况;

mSpinner.setSelection(0);

代替上述语句

mSpinner.setSelection(0,false);//只是简单地不动画它

编辑:此方法不适用于Mi Android版本的Mi UI。