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.
}
}
}
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
}
在抽出我的头发很长一段时间后，现在我已经创建了自己的Spinner类。我已经添加了一个方法，它可以适当地断开和连接侦听器。
public class SaneSpinner extends Spinner {
public SaneSpinner(Context context) {
super(context);
}
public SaneSpinner(Context context, AttributeSet attrs) {
super(context, attrs);
}
public SaneSpinner(Context context, AttributeSet attrs, int defStyleAttr) {
super(context, attrs, defStyleAttr);
}
// set the ceaseFireOnItemClickEvent argument to true to avoid firing an event
public void setSelection(int position, boolean animate, boolean ceaseFireOnItemClickEvent) {
OnItemSelectedListener l = getOnItemSelectedListener();
if (ceaseFireOnItemClickEvent) {
setOnItemSelectedListener(null);
}
super.setSelection(position, animate);
if (ceaseFireOnItemClickEvent) {
setOnItemSelectedListener(l);
}
}
}
在XML中像这样使用它:
<my.package.name.SaneSpinner
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:id="@+id/mySaneSpinner"
android:entries="@array/supportedCurrenciesFullName"
android:layout_weight="2" />
你所要做的就是在膨胀和调用集选择之后检索SaneSpinner实例:
mMySaneSpinner.setSelection(1, true, true);
这样，就不会触发任何事件，用户交互也不会中断。这大大降低了我的代码复杂性。这应该包括在Android的股票，因为它确实是一个PITA。
我的解决方案使用onTouchListener，但不限制它的使用。如果需要，它会在设置onItemSelectedListener时为onTouchListener创建一个包装器。
public class Spinner extends android.widget.Spinner {
/* ...constructors... */
private OnTouchListener onTouchListener;
private OnItemSelectedListener onItemSelectedListener;
@Override
public void setOnItemSelectedListener(OnItemSelectedListener listener) {
onItemSelectedListener = listener;
super.setOnTouchListener(wrapTouchListener(onTouchListener, onItemSelectedListener));
}
@Override
public void setOnTouchListener(OnTouchListener listener) {
onTouchListener = listener;
super.setOnTouchListener(wrapTouchListener(onTouchListener, onItemSelectedListener));
}
private OnTouchListener wrapTouchListener(final OnTouchListener onTouchListener, final OnItemSelectedListener onItemSelectedListener) {
return onItemSelectedListener != null ? new OnTouchListener() {
@Override
public boolean onTouch(View view, MotionEvent motionEvent) {
Spinner.super.setOnItemSelectedListener(onItemSelectedListener);
return onTouchListener != null && onTouchListener.onTouch(view, motionEvent);
}
} : onTouchListener;
}
}
