如何在Android中将默认值设置为微调器下拉列表？

Question

我需要将默认值文本"选择你的设备"值设置为我的微调器下拉列表,我把它作为列表项,所以它作为一个下拉列表项,我隐藏下拉列表,因为这我的下拉列表中有一个空白区域.

我该怎么做？

这是我用过的代码

mToolbar = (Toolbar) findViewById(R.id.toolbar_actionbar);
        setSupportActionBar(mToolbar);
        getSupportActionBar().setDisplayShowHomeEnabled(true);
        getSupportActionBar().setDisplayShowTitleEnabled(false);

        /*Setup a Spinner*/
        mToolbarSpinner = (Spinner) findViewById(R.id.spinner_toolbar);

        /*Manage the spinner*/
        mToolbarSpinnerNavigationItems = new ArrayList<SpinnerNavItem>();

        mToolbarSpinnerNavigationItems.add(new SpinnerNavItem("Select your Seebo", R.drawable.deviceonline));

        /*setting the mToolbarSpinnerNavigationItems to list_item_title_navigation.xml*/
        mArrayAdapter = new ArrayAdapter(this, R.layout.list_item_title_navigation,mToolbarSpinnerNavigationItems){
            @Override
            public View getView(int position, View convertView, ViewGroup parent) {

                // remember to inflate custom layout for spinner item
                // then set anything you want here
                // remember to use convertView.findViewById(), not just findViewById()

                // this is an example
                // inflate layout
                convertView = View.inflate(MainActivity.this, R.layout.list_item_title_navigation, null);
                // get view
                TextView tvText1 = (TextView) convertView.findViewById(R.id.devicetitle);
                ImageView imgIcon = (ImageView) convertView.findViewById(R.id.deviceicon);
                imgIcon.setVisibility(View.GONE);
                //imgIcon.setImageResource(mToolbarSpinnerNavigationItems.get(position).getIcon());
                // set content
                tvText1.setText(mToolbarSpinnerNavigationItems.get(position).getTitle());
                // return
                return convertView;
            }

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

                return convertView;
            }

        };

        //setting adapter to Spinner
        mToolbarSpinner.setAdapter(mArrayAdapter);

Answer 1

至于我对你的问题的理解,你可以做的是通过让它从-1而不是0开始索引来覆盖Spinner view它,这样就可以使数组的第一个条目成为你想要的那个.

选择您的设备

StackOverflow上已存在多个问题,您可以参考这些问题并进行覆盖,建议使用通用解决方案.

请参考这里.

或者反过来说,您也可以使用以下代码片段设置微调器的自定义默认位置:

ArrayAdapter<String> spinnerAdap = (ArrayAdapter<String>) mySpinner.getAdapter();

int spinnerPosition = messgAdap.getPosition(theDefaultValue);

mySpinner.setSelection(spinnerPosition);

Answer 2

你可以使用像，

final ArrayList<String> strDeviceArr = new ArrayList<>();
      strDeviceArr.add("Select device");
      strDeviceArr.add("Nexus X");
      strDeviceArr.add("Nexus XL");

      spnrDevice.setAdapter(new ArrayAdapter<>(MainActivity.this, R.layout
        .layout_spinner_textview, R.id.textView, strDeviceArr));

      spnrDevice.setSelection(0); //set default selection to 0

      spnrDevice.setOnItemSelectedListener(new AdapterView.OnItemSelectedListener() {
         @Override
         public void onItemSelected(AdapterView<?> parent, View view, int position, long id) {
            String valueSelected = strDeviceArr.get(position);
         }

         @Override
         public void onNothingSelected(AdapterView<?> parent) {

         }
      });