spinner中的onNothingSelected方法到底什么时候调用？

这个东东大家在开发中可能不太能用到，所以总是容易被忽略，由于工作原因，我最近琢磨了一下onNothingSelected方法的调用时机问题，其实很简单，只要我们稍微看一下源码就明白了：

  

   

    

     

    
    

     
 /**
     
    
   

    

     

    
    

     

       * Callback method to be invoked when the selection disappears from this
     
    
   

    

     

    
    

     

       * view. The selection can disappear for instance when touch is activated
     
    
   

    

     

    
    

     

       * or when the adapter becomes empty.
     
    
   

    

     

    
    

     

       *
     
    
   

    

     

    
    

     

       * @param parent The AdapterView that now contains no selected item.
     
    
   

    

     

    
    

     

       */
     
    
   

    

     

    
    

     
 void onNothingSelected(AdapterView<?> parent);
     
    
  
 

  

   

    

     

    
    

     
	@Override
     
    
   

    

     

    
    

     
	protected void onCreate(Bundle savedInstanceState) {
     
    
   

    

     

    
    

     
		super.onCreate(savedInstanceState);
     
    
   

    

     

    
    

     

      		setContentView(R.layout.activity_main);
     
    
   

    

     

    
    

     

      		initData();
     
    
   

    

     

    
    

     

      		provinces = (Spinner) this.findViewById(R.id.provinces);
     
    
   

    

     

    
    

     

      		adapter = new ArrayAdapter<String>(this, android.R.layout.simple_spinner_dropdown_item,
     
    
   

    

     

    
    

     

       data);
     
    
   

    

     

    
    

     

      		provinces.setAdapter(adapter);
     
    
   

    

     

    
    

     

      		provinces.setOnItemSelectedListener(new OnItemSelectedListener() {
     
    
   

    

     

    
    

     
 
     
    
   

    

     

    
    

     
			@Override
     
    
   

    

     

    
    

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

    

     

    
    

     

       Log.d("qianfeng", "您选择了" + data.get(position));
     
    
   

    

     

    
    

     

      			}
     
    
   

    

     

    
    

     
 
     
    
   

    

     

    
    

     
			@Override
     
    
   

    

     

    
    

     
			public void onNothingSelected(AdapterView<?> parent) {
     
    
   

    

     

    
    

     

       Log.d("qianfeng", "NothingSelected");
     
    
   

    

     

    
    

     

      			}
     
    
   

    

     

    
    

     

      		});
     
    
   

    

     

    
    

     

      	}
     
    
   

    

     

    
    

     
	
     
    
   

    

     

    
    

     
	/**
     
    
   

    

     

    
    

     

       * 点击button时，将集合中的数据全部移除，同时调用adapter的notifyDataSetChanged方法
     
    
   

    

     

    
    

     

       * @param view
     
    
   

    

     

    
    

     

       */
     
    
   

    

     

    
    

     
	public void btnClick(View view){
     
    
   

    

     

    
    

     

      		data.removeAll(data);
     
    
   

    

     

    
    

     

      		adapter.notifyDataSetChanged();
     
    
   

    

     

    
    

     

      	}
     
    
   

    

     

    
    

     
 
     
    
   

    

     

    
    

     
	private void initData() {
     
    
   

    

     

    
    

     

      		data = new ArrayList<String>();
     
    
   

    

     

    
    

     

      		data.add("山东");
     
    
   

    

     

    
    

     

      		data.add("广西");
     
    
   

    

     

    
    

     

      		data.add("陕西");
     
    
   

    

     

    
    

     

      		data.add("广东");
     
    
   

    

     

    
    

     

      	}
     
    
  
 

文章来源: wangsong.blog.csdn.net，作者：_江南一点雨，版权归原作者所有，如需转载，请联系作者。

原文链接：wangsong.blog.csdn.net/article/details/50598673