Question

我使用微调器在Calendar类上显示日期。

我可以得到年份和月份，但我无法在spinner获得一天的价值。

显示

java.lang.NullPointerException: Attempt to invoke virtual method 'java.lang.String java.lang.Object.toString()' on a null object reference

我该如何解决这个问题？

以下是代码：

private void datePick(){
        Calendar calendar = Calendar.getInstance();

        for (int i = 0; i < 100; i++) {
            dataYear.add("" + (calendar.get(Calendar.YEAR) - i));
        }

        adapterSpYear = new ArrayAdapter<String>(getActivity(), R.layout.spinner, dataYear);
        adapterSpYear.setDropDownViewResource(R.layout.support_simple_spinner_dropdown_item);
        spYear.setAdapter(adapterSpYear);
        spYear.setSelection(34);//for 1982

        for (int i = 1; i <= 12; i++) {
            dataMonth.add("" + (i < 10 ? "0" + i : i));
        }

        adapterSpMonth = new ArrayAdapter<String>(getActivity(), R.layout.spinner, dataMonth);
        adapterSpMonth.setDropDownViewResource(R.layout.support_simple_spinner_dropdown_item);
        spMonth.setAdapter(adapterSpMonth);


        adapterSpDay = new ArrayAdapter<String>(getActivity(), R.layout.spinner, dataDay);
        adapterSpDay.setDropDownViewResource(android.R.layout.simple_spinner_dropdown_item);
        spDay.setAdapter(adapterSpDay);

        spMonth.setOnItemSelectedListener(new AdapterView.OnItemSelectedListener() {
            @Override
            public void onItemSelected(AdapterView<?> adapterView, View view, int arg2, long arg3) {
                dataDay.clear();
                Calendar calendar1 = Calendar.getInstance();
                calendar1.set(Calendar.YEAR, Integer.valueOf(spYear.getSelectedItem().toString()));
                calendar1.set(Calendar.MONTH, arg2);
                int dayOfMonth = calendar1.getActualMaximum(Calendar.DAY_OF_MONTH);
                for (int i = 1; i <= dayOfMonth; i++) {
                    dataDay.add("" + (i < 10 ? "0" + i : i));
                }
                adapterSpDay.notifyDataSetChanged();


                String year=spYear.getSelectedItem().toString();
                String month=spMonth.getSelectedItem().toString();
                String day=spDay.getSelectedItem().toString();

                Log.i("test",".>>>>Year>>>>"+year);
                Log.i("test",".>>>>Month>>>>"+month);
                Log.i("test",".>>>>Day>>>>"+day);
            }

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

            }
        });
    }

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Answer 1

在Spinner Adapter adapterSpDay.notifyDataSetChanged();中不会刷新适配器数据。您必须在

中再次创建适配器并设置适配器

   spMonth.setOnItemSelectedListener(new AdapterView.OnItemSelectedListener() {
            @Override
            public void onItemSelected(AdapterView<?> adapterView, View view, int arg2, long arg3) 
             {  // Here create adapter for day again by passing new data and set that adapter to day spinner.
                ............
                      }

当我使用Calendar时，如何获得我的微调器值

1 个答案: