如何将微调器中的第一个值(默认值)设置为空 [英] How to set my first value (default value) in spinner as empty

问题描述

如何将微调器中的第一个值(默认值)设置为空.意味着，直到用户从列表中选择值，微调器将没有值.我在下面尝试过

How to set my first value (default value) in spinner as empty. Means, until the user selects value from list, spinner will have no value. I tried below

list.add(""); 

但是，它不起作用.下面是我的代码:

But, it won't work. Below is my code :

if(values.contains("options")){
       spinner.setOnItemSelectedListener(MyClass.this);
       List<String> list = new ArrayList<String>();
       list.add("");
       list.add("Test");
       list.add("Working");
       ArrayAdapter<String> adapter = new ArrayAdapter<String>(mContext, android.R.layout.simple_spinner_item, list) {};

      adapter.setDropDownViewResource(R.layout.custom_spinner_list);
      spinner.setAdapter(adapter);     
   }
 }

推荐答案

我找到了解决方法.这是我们的操作方法，让最后一行是

i found out the way. Here is how we do it, let the last line be

list.add("");

并添加以下代码:

ArrayAdapter<String> adapter = new ArrayAdapter<String>(mContext, android.R.layout.simple_spinner_item, list) {

                        @Override
                        public View getView(int position, View convertView, ViewGroup parent) {

                                View v = super.getView(position, convertView, parent);
                                if (position == getCount()) {
                                    ((TextView)v.findViewById(android.R.id.text1)).setText("");
                                    ((TextView)v.findViewById(android.R.id.text1)).setHint(getItem(getCount())); //"Hint to be displayed"
                                }

                                return v;
                            }       

                            @Override
                            public int getCount() {
                                return super.getCount()-1;            // you don't display last item. It is used as hint.
                            }

                    };


                    adapter.setDropDownViewResource(R.layout.custom_spinner_list);
                    spinner.setAdapter(adapter);
                    spinner.setSelection(adapter.getCount());        //set the hint the default selection so it appears on launch.
                    spinner.setOnItemSelectedListener(this);
                    notifyDataSetChanged();        

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