微調器 - 重點對第一項

Question

我使用下拉微調與光標適配器。它包含例如1 - 100項。 我選擇了例如項目50.選擇項目。下一次，當我打開微調第一個可見行是項目50.我怎麼能達到這一點，當我打開微調它將集中到第一個項目/第一個可見項目將項目1？

我的意思是像列表中的自動滾動，所以下拉菜單中的第一個可見項目是第一個，沒有選擇一個。

Answer 1

可以使Spinner做你想做的通過擴展它和重寫兩種方法，分別負責設置/顯示值列表：

public class CustomSpinnerSelection extends Spinner { 

    private boolean mToggleFlag = true; 

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

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

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

    public CustomSpinnerSelection(Context context, int mode) { 
     super(context, mode); 
    } 

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

    @Override 
    public int getSelectedItemPosition() { 
     // this toggle is required because this method will get called in other 
     // places too, the most important being called for the 
     // OnItemSelectedListener 
     if (!mToggleFlag) { 
      return 0; // get us to the first element 
     } 
     return super.getSelectedItemPosition(); 
    } 

    @Override 
    public boolean performClick() { 
     // this method shows the list of elements from which to select one. 
     // we have to make the getSelectedItemPosition to return 0 so you can 
     // fool the Spinner and let it think that the selected item is the first 
     // element 
     mToggleFlag = false; 
     boolean result = super.performClick(); 
     mToggleFlag = true; 
     return result; 
    } 

} 

這應該只是罰款什麼你想要做的。

Answer 2

可以Spinner的選擇設置這樣的第一個項目：

yourspinner.setSelection(0); 

您可能要做到這一點的在onStart（）方法。

Answer 3

這段短小的代碼將爲您完成這項工作。

int prevSelection=0; 
    spSunFrom = (Spinner) findViewById(R.id.spTimeFromSun); 
    spSunFrom.setOnTouchListener(new OnTouchListener() { 

     public boolean onTouch(View v, MotionEvent event) { 
      // TODO Auto-generated method stub 
      prevSelection = spSunFrom.getSelectedItemPosition(); 
      spSunFrom.setSelection(0); 
      return false; 
     } 
    }); 
    spSunFrom.setOnItemSelectedListener(new OnItemSelectedListener() { 

     @Override 
     public void onItemSelected(AdapterView<?> arg0, View arg1, 
       int arg2, long arg3) { 
      if(arg2==0) 
       spSunFrom.setSelection(prevSelection); 
      prevSelection = arg2; 

     } 

     @Override 
     public void onNothingSelected(AdapterView<?> arg0) { 
      spSunFrom.setSelection(prevSelection); 
     } 
    });