再次选择当前选定的项目时，如何在 Android Spinner 中获取事件？

Question

我已经为微调器编写了一个 setOnItemSelectedListener 以在微调器项目更改时做出响应。我的要求是当我再次单击当前选定的项目时，应该显示一个 toast。如何获得这个活动？再次单击当前选定的项目时，微调器没有响应。 `

    StorageSpinner.setOnItemSelectedListener(new AdapterView.OnItemSelectedListener(){

        @Override
        public void onItemSelected(AdapterView adapter, View v, int i, long lng) {              
            Toast.makeText(getApplicationContext(), (CharSequence) StorageSpinner.getSelectedItem(), Toast.LENGTH_SHORT).show();

        }

        @Override
        public void onNothingSelected(AdapterView arg0) {
            Toast.makeText(getApplicationContext(), "Nothing selected", Toast.LENGTH_SHORT).show();

        }
    });  

Answer 1

我花了好几个小时试图解决这个问题。我结束了以下。我不确定它是否适用于所有情况，但它似乎对我有用。它只是 Spinner 类的扩展，它检查选择并在选择设置为相同值时调用侦听器。

import android.content.Context;
import android.util.AttributeSet;
import android.widget.Spinner;


/** Spinner extension that calls onItemSelected even when the selection is the same as its previous value */
public class NDSpinner extends Spinner {

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

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

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

    @Override 
    public void setSelection(int position, boolean animate) {
        boolean sameSelected = position == getSelectedItemPosition();
        super.setSelection(position, animate);
        if (sameSelected) {
            // Spinner does not call the OnItemSelectedListener if the same item is selected, so do it manually now
            getOnItemSelectedListener().onItemSelected(this, getSelectedView(), position, getSelectedItemId());
        }
    } 

    @Override
    public void setSelection(int position) {
        boolean sameSelected = position == getSelectedItemPosition();
        super.setSelection(position);
        if (sameSelected) {
            // Spinner does not call the OnItemSelectedListener if the same item is selected, so do it manually now
            getOnItemSelectedListener().onItemSelected(this, getSelectedView(), position, getSelectedItemId());
        }
    }

}

Answer 2

试试这个

public class MySpinner extends Spinner{

OnItemSelectedListener listener;

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

    @Override
    public void setSelection(int position)
    {
        super.setSelection(position);

        if (position == getSelectedItemPosition())
        {
            listener.onItemSelected(null, null, position, 0);
        }       
    }

    public void setOnItemSelectedListener(OnItemSelectedListener listener)
    {
        this.listener = listener;
    }
}

Answer 3

此微调器将始终告诉您选择已更改：

package com.mitosoft.ui.widgets;

import java.lang.reflect.Method;
import android.content.Context;
import android.content.DialogInterface;
import android.util.AttributeSet;
import android.util.Log;
import android.widget.AdapterView;
import android.widget.Spinner;

//com.mitosoft.ui.widgets.NoDefaultSpinner
public class NoDefaultSpinner extends Spinner {

    private int lastSelected = 0;
    private static Method s_pSelectionChangedMethod = null;


    static {        
        try {
            Class noparams[] = {};
            Class targetClass = AdapterView.class;

            s_pSelectionChangedMethod = targetClass.getDeclaredMethod("selectionChanged", noparams);            
            if (s_pSelectionChangedMethod != null) {
                s_pSelectionChangedMethod.setAccessible(true);              
            }

        } catch( Exception e ) {
            Log.e("Custom spinner, reflection bug:", e.getMessage());
            throw new RuntimeException(e);
        }
    }

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

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

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

    public void testReflectionForSelectionChanged() {
        try {
            Class noparams[] = {};          
            s_pSelectionChangedMethod.invoke(this, noparams);
        } catch (Exception e) {
            Log.e("Custom spinner, reflection bug: ", e.getMessage());
            e.printStackTrace();                
        }
    } 




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

            lastSelected = which;
    }
}

Answer 4

我想我会为那些使用较新 Android 版本的人留下一个更新的答案。

我根据上述答案编译了一个函数，该函数至少适用于 4.1.2 和 4.3（我测试过的设备）。此函数不使用反射，而是跟踪最后选择的索引本身，因此即使 SDK 更改了类相互扩展的方式，也应该可以安全使用。

import android.content.Context;
import android.util.AttributeSet;
import android.widget.Spinner;

public class SelectAgainSpinner extends Spinner {

    private int lastSelected = 0;

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

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

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

    @Override
    protected void onLayout(boolean changed, int l, int t, int r, int b) {
        if(this.lastSelected == this.getSelectedItemPosition() && getOnItemSelectedListener() != null)
            getOnItemSelectedListener().onItemSelected(this, getSelectedView(), this.getSelectedItemPosition(), getSelectedItemId());
        if(!changed)
            lastSelected = this.getSelectedItemPosition();

        super.onLayout(changed, l, t, r, b);
    } 
}

Answer 5

kotlin，希望对你有帮助

import android.content.Context
import android.util.AttributeSet
import androidx.appcompat.widget.AppCompatSpinner

class MoreSpinner : AppCompatSpinner {

    constructor(context: Context) : super(context)
    constructor(context: Context, attrs: AttributeSet?) : super(context, attrs)
    constructor(context: Context, attrs: AttributeSet?, defStyleAttr: Int) : super(context, attrs, defStyleAttr)

    override fun setSelection(position: Int, animate: Boolean) {
        val sameSelected = position == selectedItemPosition
        super.setSelection(position, animate)
        if (sameSelected) {
            onItemSelectedListener?.onItemSelected(
                this,
                selectedView,
                position,
                selectedItemId
            )
        }
    }

    override fun setSelection(position: Int) {
        val sameSelected = position == selectedItemPosition
        super.setSelection(position)
        if (sameSelected) {
            onItemSelectedListener?.onItemSelected(
                this,
                selectedView,
                position,
                selectedItemId
            )
        }
    }
}

Answer 6

对于较新的平台，请尝试将此添加到 Dimitar 的解决方案中。我认为它有效:)

（你必须重写 onLayout 并移除 onClick 方法）

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

@Override
protected void onLayout(boolean changed, int l, int t, int r, int b) {
    if(this.lastSelected == this.getSelectedItemPosition())
        testReflectionForSelectionChanged();
    if(!changed)
        lastSelected = this.getSelectedItemPosition();

    super.onLayout(changed, l, t, r, b);
} 

Answer 7

我发现，如果在微调器中再次选择相同的项目，则不会调用 OnItemSelectedListener。当我单击微调器并再次选择相同的值时，不会调用 OnItemSelectedListener 方法。如果根据 UI 设计单击已经处于活动状态的选择，人们不会期望发生任何事情。

Answer 8

@Dimitar。哇，出色的工作。感谢那。我不能支持您的解决方案（分数不够），但 NoDefaultSpinner 类有效。只有这一件事是一个问题：因为您在“OnClick”中调用 super.onClick 然后 testReflectionForSelectionChanged()，如果选择确实发生了变化，您将获得微调器的 onItemSelected 处理程序被调用两次（而功能是正确的，如果相同项目被重新选择）。我通过破解它解决了这个问题。我添加了一个 onTouchEvent 覆盖，记录了哪个项目被触摸，然后检查它是否在“onClick”中发生了变化：

private Object ob=null; //class level variable
 @Override
public boolean onTouchEvent(MotionEvent m)
{
    if (m.getAction()==MotionEvent.ACTION_DOWN)
    {
        ob=this.getSelectedItem();
    }
    return super.onTouchEvent(m);
}
@Override
public void onClick(DialogInterface dialog, int which) {    
    super.onClick(dialog, which);
    if (this.getSelectedItem().equals(ob))
        testReflectionForSelectionChanged();
}

Answer 9

从这个答案继续https://stackoverflow.com/a/17099104/7392507

在您的 xml 文件中，创建一个微调器。将微调器标签 <Spinner> 替换为 <yourdomain.yourprojectname.yourpackagename.spinnerclassname>，例如 <com.company.appname.utility.MySpinner>。

在您的 java 文件中，定义 spinner 变量，如下所示： -Spinnerclassname varName = findViewById(R.id.spinnerId);

例如： -MySpinner varSpinner = findViewById(R.id.spinnerId);

Answer 10

这不是完整的解决方案，但如果您只想在从任何地方返回片段/活动时调用它，它就可以工作。

考虑到 mSpinner 是您的 Spinner 视图，我们这样称呼它的监听器：

@Override public void onResume() {
        if (mSpinner.getCount() > 0) {
            mSpinner.getOnItemSelectedListener()
                    .onItemSelected( mSpinner, null, mSpinner.getSelectedItemPosition(), 0 );
        }
        super.onResume();
    }

Answer 11

您好，感谢@Dimitar 对这个问题的创造性回答。我已经尝试过了，它在 2.x 等较旧的 Android 版本上运行良好，但不幸的是，它不适用于 3.0 及更高版本（已尝试 3.2 和 4.0.3）。由于某种原因，onClick 方法永远不会在较新的平台上调用。有人在这里写了一个错误报告：http://code.google.com/p/android/issues/detail?id=16245

无法在较新的平台上运行意味着我需要不同的解决方案。在我的应用程序中，模拟一个未选中的微调器就足够了，并在开始时隐藏了一个“虚拟”条目。然后，如果将“隐藏”项设置为选择项，则单击的每个项都会导致回调。对某些人来说，一个缺点可能是不会显示任何内容，但可以使用 Spinner 类覆盖技巧来解决这个问题。

见How to hide one item in an Android Spinner

Answer 12

我们的要求不会出现 Spinner 行为。我的解决方案不适用于 Spinners，以一种类似的方式进行，在一个 BaseFragment 中使用一个 ListView 来研究我们所期望的功能。

好处是：

1. 扩展 Spinner 默认设置不再令人头疼。
2. 易于实施和定制。
3. 完全兼容所有 Android API。
4. 第一次 OnItemSelectedListener.onItemSelected 调用没有面子。

主要思想是做这样的事情：

BaseFragment 布局可能类似于：

<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
              android:background="@null"
              android:layout_width="match_parent"
              android:layout_height="match_parent"
              android:orientation="vertical"
              android:gravity="center">

    <ListView
            android:id="@+id/fragment_spinnerList"
            android:layout_width="wrap_content"
            android:layout_height="wrap_content"/>
</LinearLayout>

代码如下所示：

public class SpinnerListFragment extends android.support.v4.app.DialogFragment {

    static SpinnerListFragment newInstance(List<String> items) {

        SpinnerListFragment spinnerListFragment = new SpinnerListFragment();
        Bundle args = new Bundle();

        args.putCharSequenceArrayList("items", (ArrayList) items);
        spinnerListFragment.setArguments(args);

        return spinnerListFragment;
    }

    @Override
    public Dialog onCreateDialog(Bundle savedInstanceState) {

        Dialog dialog = new Dialog(getActivity(), R.style.dialog);
        final View view = getActivity().getLayoutInflater().inflate(R.layout.dialog_spinner_list, null);

        dialog.getWindow().setContentView(view);
        dialog.setCanceledOnTouchOutside(true);

        // CUSTOMIZATION...

        final List items = (ArrayList) getArguments().getCharSequenceArrayList("items");

        final ListView spinnerList = (ListView) view.findViewById(R.id.fragment_spinnerList);

        ArrayAdapter<String> arrayAdapter =
                new ArrayAdapter<String>(
                        getActivity(),
                        R.layout.search_spinner_list_item,
                        items);

        spinnerList.setAdapter(arrayAdapter);

        spinnerList.setOnItemClickListener(new AdapterView.OnItemClickListener() {

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

                // DO SOMETHING...

                SpinnerListFragment.this.dismiss();
            }
        });

        return dialog;
    }

}

Answer 13

我的解决方案是基于 benoffi7 的 MySpinner。通过保存最后选择的父项和视图来修复在同一项目选择上传递空值。

public class MySpinner extends Spinner {

    private OnItemSelectedListener listener;
    private AdapterView<?> lastParent;
    private View lastView;
    private long lastId;

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

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

    private void initInternalListener() {
        super.setOnItemSelectedListener(new OnItemSelectedListener() {

            @Override
            public void onItemSelected(AdapterView<?> parent, View view,
                int position, long id) {
                lastParent = parent;
                lastView = view;
                lastId = id;
                if (listener != null) {
                    listener.onItemSelected(parent, view, position, id);
                }
            }

            @Override
            public void onNothingSelected(AdapterView<?> parent) {
                //lastParent = parent; // do we need it?
                if (listener != null) {
                    listener.onNothingSelected(parent);
                }
            }
        });
    }

    @Override
    public void setSelection(int position) {
        if (position == getSelectedItemPosition() && listener != null) {
            listener.onItemSelected(lastParent, lastView, position, lastId);
        } else {
            super.setSelection(position);
        }
    }

    @Override
    public void setOnItemSelectedListener(OnItemSelectedListener listener) {
        this.listener = listener;
    }
}

Answer 14

class MySpinner extends Spinner {


    public MySpinner(Context context) {
        super(context);
        // TODO Auto-generated constructor stub
    }
    public MySpinner(Context context, AttributeSet attrs)
    {
        super(context, attrs);
    }
    @Override
    public void setSelection(int position, boolean animate) {
        ignoreOldSelectionByReflection();
        super.setSelection(position, animate);
    }

    private void ignoreOldSelectionByReflection() {
        try {
            Class<?> c = this.getClass().getSuperclass().getSuperclass().getSuperclass();
            Field reqField = c.getDeclaredField("mOldSelectedPosition");
            reqField.setAccessible(true);
            reqField.setInt(this, -1);
        } catch (Exception e) {
            Log.d("Exception Private", "ex", e);
            // TODO: handle exception
        }
    }

    @Override
    public void setSelection(int position) {
        ignoreOldSelectionByReflection();
        super.setSelection(position);
    }

}

Answer 15

这是一个简单的解决方案，因为可以基于“onTouch”以编程方式设置“选定项”，如下所示：

spinnerobject.setOnTouchListener(new AdapterView.OnTouchListener() {
        @Override
        public boolean onTouch(View v, MotionEvent event) {

            final int MAKE_A_SELECTION = 1; //whatever index that is the normal starting point of the spinner.
            spinnerObject.setSelection(MAKE_A_SELECTION);
            return false;
        }
    });

有一个微小的损失，即 (1) 微调器文本将在显示微调器行之前更改回默认值，以及 (2) 此默认项将成为列表的一部分。也许有人可以添加如何禁用微调器的特定项目？

一般来说，由于微调器选择可能会执行可重复的事件（例如开始搜索），因此无法在微调器中重新选择项目实际上是 Spinner 类中缺少的功能/错误，这是 Android 开发人员的错误应该尽快改正。

Answer 16

嗨，伙计，这对我有用：

ArrayAdapter<String> adaptador1 = new ArrayAdapter<String>( Ed_Central.this, 
                                                            android.R.layout.simple_spinner_item,
                                                            datos1
                                                            );
        lista1.setAdapter( adaptador1 );

        lista1.setOnItemSelectedListener( new AdapterView.OnItemSelectedListener() {
            @Override
            public void onItemSelected( AdapterView<?> parent, View view, int position, long id ) {

                lista1.setSelection( 0 );

                switch ( position ) {
                    case 1:
                        Toast.makeText( getApplicationContext(), "msg1", Toast.LENGTH_SHORT ).show();
                        break;
                    case 2:
                        Toast.makeText( getApplicationContext(), "msg2", Toast.LENGTH_SHORT ).show();
                        break;
                    case 3:
                        Toast.makeText( getApplicationContext(), "msg3", Toast.LENGTH_SHORT ).show();
                        break;

                    default:
                        break;
                }
            }

适配器始终位于“0”位置，您可以展示您的 toast。

Answer 17

package customclasses;

/**
 * Created by Deepak on 7/1/2015.
 */

import android.content.Context;
import android.util.AttributeSet;
import android.widget.Spinner;

/**
 * Spinner extension that calls onItemSelected even when the selection is the same as its previous value
 */
public class NDSpinner extends Spinner {
    public boolean isDropDownMenuShown=false;

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

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

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


    @Override
    public void
    setSelection(int position, boolean animate) {
        boolean sameSelected = position == getSelectedItemPosition();
        super.setSelection(position, animate);
        if (sameSelected) {
            // Spinner does not call the OnItemSelectedListener if the same item is selected, so do it manually now
            getOnItemSelectedListener().onItemSelected(this, getSelectedView(), position, getSelectedItemId());
        }
    }

    @Override
    public boolean performClick() {
        this.isDropDownMenuShown = true; //Flag to indicate the spinner menu is shown
        return super.performClick();
    }
    public boolean isDropDownMenuShown(){
        return isDropDownMenuShown;
    }
    public void setDropDownMenuShown(boolean isDropDownMenuShown){
        this.isDropDownMenuShown=isDropDownMenuShown;
    }
    @Override
    public void
    setSelection(int position) {
        boolean sameSelected = position == getSelectedItemPosition();
        super.setSelection(position);
        if (sameSelected) {
            // Spinner does not call the OnItemSelectedListener if the same item is selected, so do it manually now
            getOnItemSelectedListener().onItemSelected(this, getSelectedView(), position, getSelectedItemId());
        }
    }
    @Override
    public void onDetachedFromWindow() {
        super.onDetachedFromWindow();
    }
}

Answer 18

在 Kotlin 中具有相同项目选择回调的自定义微调器：

class StorageSpinner : AppCompatSpinner {

    constructor(context: Context) : super(context)
    constructor(context: Context, attrs: AttributeSet?) : super(context, attrs)
    constructor(context: Context, attrs: AttributeSet?, defStyleAttr: Int) : super(context, attrs, defStyleAttr)

    interface StorageSpinnerSelectionCallback {
        fun onItemSelected(position: Int)
    }

    private var selectionCallback: StorageSpinnerSelectionCallback? = null

    fun setSelectionCallback(selectionCallback: StorageSpinnerSelectionCallback) {
        this.selectionCallback = selectionCallback
    }

    fun removeSelectionCallback() {
        selectionCallback = null
    }

    override fun setSelection(position: Int) {
        super.setSelection(position)

        if (position == selectedItemPosition) selectionCallback?.onItemSelected(position)
    }
}

Answer 19

试试这个，这可能不是正确的解决方案，但如果不制作自定义微调器，这可能是目前可用的最佳解决方案。

您要做的是在每次点击项目时重置微调器适配器，

 @Override
    public void onItemSelected(AdapterView adapter, View v, int position, long lng) {              

    if (position == getSelectedItemPosition())
    {
        //do your thing
        //then at end of statement reset adapter like

       spinner.setAdapter(adapter);
    } 

    }

希望能帮到你解决问题

Answer 20

如果您真的想在您的 XML 中执行此任务，当您的微调器显示添加一个编辑文本并设置可见性消失属性时；并为微调器创建服装适配器，并在 view.onclicklisner 上设置的服装适配器以及 clickevent 触发 EditText.setText("0");并在活动集 edittext textWatcher 事件和事件块中添加您的 onSpinerItem 事件块代码；你的问题解决了

Answer 21

您必须执行以下步骤： 1.为微调器创建一个适配器客户 2.在override fun getDropDownView(...)中，必须放一个view.setOnClickListener {"interface"} 3. 创建界面

Answer 22

无需扩展微调器。 我以下列方式使用 SpinnerAdapter：

    public View onCreateView(LayoutInflater inflater, ViewGroup container, Bundle  savedInstanceState) {
    //....
    //Create an ArrayAdapter as usual
    myArrayAdapter = new ArrayAdapter(mParentView.getContext(),R.layout.myarrayadapter_item);
    //Create a Spinner as usual
    mySpinner = (Spinner)mParentView.findViewById(R.id.myspinner);

    //create a spinneradapter
    //selecting the same item twice will not throw an onselectionchange event
    //therefore add an OnTouchlistener to the DropDownView items
    SpinnerAdapter o_SpinnerAdapter = new SpinnerAdapter() {
            private ArrayAdapter m_ArrayAdapter = myArrayAdapter;
            private View.OnTouchListener m_OnTouchListener = new View.OnTouchListener() {
            @Override
            public boolean onTouch(View v, MotionEvent event) {
                    //do something
                   return false; //return false, don't consume the event
            };
            @Override
            public View getDropDownView(int position, View convertView, ViewGroup parent) {
                    TextView o_TextView; //usual the view is a TextView
                    o_TextView = (TextView)m_ArrayAdapter.getView(position,convertView,parent);
                    o_TextView.setOnTouchListener(m_OnTouchListener); //Add the ontouchlistener
                    return o_TextView;
            }

            @Override
            public void registerDataSetObserver(DataSetObserver observer) {
                    m_ArrayAdapter.registerDataSetObserver(observer);
            }
            @Override
            public void unregisterDataSetObserver(DataSetObserver observer) {
                    m_ArrayAdapter.unregisterDataSetObserver(observer);
            }
            @Override
            public int getCount() {
                    return m_ArrayAdapter.getCount();
            }
            @Override
            public Object getItem(int position) {
                    return m_ArrayAdapter.getItem(position);
            }
            @Override
            public long getItemId(int position) {
                    return m_ArrayAdapter.getItemId(position);
            }
            @Override
            public boolean hasStableIds() {
                    return m_ArrayAdapter.hasStableIds();
            }
            @Override
            public View getView(int position, View convertView, ViewGroup parent) {
                    return m_ArrayAdapter.getView(position, convertView, parent);
            }
            @Override
            public int getItemViewType(int position) {
                    return m_ArrayAdapter.getItemViewType(position);
            }
            @Override
            public int getViewTypeCount() {
                    return m_ArrayAdapter.getViewTypeCount();
            }
            @Override
            public boolean isEmpty() {
                    return m_ArrayAdapter.isEmpty();
            }
    };
    //Set the SpinnerAdapter instead of myArrayAdapter
    m_SpinnerDMXDeviceGroups.setAdapter(o_SpinnerAdapter);

    //.......
    }

希望对你有帮助

Answer 23

试试这个。

@Override
public void onItemSelected(AdapterView adapter, View v, int i, long lng) {  

    if(v.hasFocus() {            
        Toast.makeText(getApplicationContext(), (CharSequence) StorageSpinner.getSelectedItem(), Toast.LENGTH_SHORT).show();
    }    
}

希望它可以工作。

Answer 24

当您再次单击当前选定的项目时，它不会触发任何事件。因此，您无法捕获 setOnItemSelectedListener 以使微调器响应。