Spinner ()执行不当

Question

可能重复：

Android Spinner OnItemSelected Called Erroneously (without user action on opening spinner)

当布局被实例化时，有人知道如何防止onItemSelected() (OnItemSelectedListener接口)方法运行吗？我需要知道是否有办法做到这一点，因为我希望将我的布局实例化方式与这个侦听器分开。

我尝试在重写方法中的所有代码周围创建一个最初设置为false的if语句，但是无法知道何时将其设置为true，因为重写的方法每次运行在onCreate()、onStart()和onResume()方法之后。

关于这一点，我没有找到明确的答案。任何明确的解决方案都将不胜感激。

Answer 1

大卫，这是我为这个问题写的教程.

问题陈述

当库(或旋转器)正在初始化时，会触发一个不受欢迎的onItemSelected()。这意味着代码是过早地执行的；代码只在用户实际做出选择时才会执行。

溶液

1. in onCreate()，计算视图中有多少图库(或旋转器)小部件。(mGalleryCount)
2. in onItemSelected()，计算它触发的频率。(mGalleryInitializedCount)
3. when (mGalleryInitializedCount < mGalleryCount) == false，然后执行用于用户

的代码

代码示例

public class myActivity extends Activity implements OnItemSelectedListener
{
    //this counts how many Gallery's are on the UI
    private int mGalleryCount=0;

    //this counts how many Gallery's have been initialized
    private int mGalleryInitializedCount=0;

    //UI reference
    private Gallery mGallery;


    @Override
    public void onCreate(Bundle savedInstanceState)
    {

        super.onCreate(savedInstanceState);
        setContentView(R.layout.myxmllayout);

        //get references to UI components
        mGallery = (Gallery) findViewById(R.id.mygallery);

        //trap selection events from gallery
        mGallery.setOnItemSelectedListener(this);

        //trap only selection when no flinging is taking place
        mGallery.setCallbackDuringFling(false);

        //
        //do other stuff like load images, setAdapter(), etc
        //

        //define how many Gallery's are in this view
        //note: this could be counted dynamically if you are programmatically creating the view
        mGalleryCount=1;

    }


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

        if (mGalleryInitializedCount < mGalleryCount)
        {
            mGalleryInitializedCount++;
        }
        else
        {
            //only detect selection events that are not done whilst initializing
            Log.i(TAG, "selected item position = " + String.valueOf(position) );
        }

    }

}

为什么这样做，

此解决方案之所以有效，是因为库在用户进行物理选择之前很久就完成了初始化。

Answer 2

这里是一个修改版本的“某人某处”的代码。如果您有一个视图，您可以使用它。

public class myActivity extends Activity implements OnItemSelectedListener
{
// Set view initialization to false while the it is being built
private boolean initializedView = false;

//UI reference
private Gallery mGallery;


@Override
public void onCreate(Bundle savedInstanceState)
{

    super.onCreate(savedInstanceState);
    setContentView(R.layout.myxmllayout);

    //get references to UI components
    mGallery = (Gallery) findViewById(R.id.mygallery);

    //trap selection events from gallery
    mGallery.setOnItemSelectedListener(this);

    //trap only selection when no flinging is taking place
    mGallery.setCallbackDuringFling(false);

    //
    //do other stuff like load images, setAdapter(), etc
    //


}


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

    if (initializedView ==  false)
    {
        initializedView = true;
    }
    else
    {
        //only detect selection events that are not done whilst initializing
        Log.i(TAG, "selected item position = " + String.valueOf(position) );
    }

}
}

Answer 3

同样的解决办法：

private int m_intSpinnerInitiCount = 0;
private static final int NO_OF_EVENTS = 1;

...

m_spnTemplates.setOnItemSelectedListener(new Spinner.OnItemSelectedListener() {
            @Override
            public void onItemSelected(AdapterView<?> parentView, 
                    View selectedItemView, int position, long id) { 

                //trying to avoid undesired spinner selection changed event, a known problem
                    if (m_intSpinnerInitiCount < NO_OF_EVENTS) {
                        m_intSpinnerInitiCount++;
                    } else {                
                        //YOUR CODE HERE
                    }                           
            }