Question

可能重复：
Android Spinner OnItemSelected Called Erroneously (without user action on opening spinner)

有人知道如何在实例化布局时阻止运行onItemSelected（）（OnItemSelectedListener接口）方法吗？我需要知道是否有办法做到这一点，因为我想保持我如何实例化我的布局与该侦听器分开。

我尝试在重写方法内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，因为重写的方法在onCreate（），onStart之后运行（每次都是onResume（）方法。

我没有找到任何明确的答案。任何明确的解决方案都将受到高度赞赏。

Answer 1

大卫，这是我为这个问题写的教程......

问题陈述

在Gallery（或Spinner）初始化时触发了一个不合需要的onItemSelected（）。这意味着代码过早地执行;仅在用户进行实际选择时才执行的代码。

<强>解决方案

在onCreate（）中，计算视图中有多少个Gallery（或Spinner）小部件。（mGalleryCount）
在onItemSelected（）中，计算它触发的频率。（mGalleryInitializedCount）
当（mGalleryInitializedCount＆lt; mGalleryCount）== false时，然后执行适合用户的代码

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) );
        }

    }

}

为什么会这样？

此解决方案有效，因为Gallery在用户实际进行选择之前很久就完成了初始化。

Answer 2

以下是“Someone Somewhere”代码的修改版本。如果您只有一个视图，则可以使用它。

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

相同的解决方案：

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
                    }                           
            }

Answer 4

昨天我用OnCheckedChangedListener遇到了这个问题。我最终在我的适配器类中添加了一个布尔实例变量，并使用访问器方法isListenerEnabled（）。然后我在布局代码中将变量设置为false，并在布局代码的末尾再次将其设置为true。在我的监听器中，我检查变量的值以决定是否执行监听器代码。

Answer 5

每次调用false时，您都可以将变量设置回onPause。至于何时将其设置为true，您可以在onResume之后为第一个动作/键/轨迹球事件执行此操作。

Answer 6

我也在互联网上寻找一个好的解决方案，但没有找到满足我需求的解决方案。所以我已经在Spinner类上编写了这个扩展，因此您可以设置一个简单的OnItemClickListener，它具有与ListView相同的行为。

只有在选择了项目时，才会调用onItemClickListener。

玩得开心！

public class MySpinner extends Spinner
{
    private OnItemClickListener onItemClickListener;


    public MySpinner(Context context)
    {
        super(context);
    }

    public MySpinner(Context context, AttributeSet attrs)
    {
        super(context, attrs);
    }

    public MySpinner(Context context, AttributeSet attrs, int defStyle)
    {
        super(context, attrs, defStyle);
    }

    @Override
    public void setOnItemClickListener(android.widget.AdapterView.OnItemClickListener inOnItemClickListener)
    {
        this.onItemClickListener = inOnItemClickListener;
    }

    @Override
    public void onClick(DialogInterface dialog, int which)
    {
        super.onClick(dialog, which);

        if (this.onItemClickListener != null)
        {
            this.onItemClickListener.onItemClick(this, this.getSelectedView(), which, this.getSelectedItemId());
        }
    }
}

Spinner onItemSelected（）执行不当

6 个答案: