java.lang.NumberFormatException：无效的双精度：“”在 java.lang.StringToReal.invalidReal

Question

您好，我正在从 edittext 中获取一个值并转换为在其他文本中显示该值，但出现运行时错误 java.lang.NumberFormatException: Invalid double: "".at java.lang.StringToReal.invalidReal。在我的 setAdapter 中，它只采用 franheit，这意味着只需要详细信息。我不明白错误在哪里

public class UniqueConverter extends Fragment {

    private Spinner fromDetails, toDetails;
    private EditText fromInput, toInput;
@Override
    public View onCreateView(LayoutInflater inflater, @Nullable ViewGroup container, @Nullable Bundle savedInstanceState) {
        View view = inflater.inflate(R.layout.fragment_uniquelayout, container, false);
onInitVies(view);
        int position = getArguments().getInt("position");
        String ifrom,rto;
        Double inp;
        double out = 0;

        switch (position) {
            case 0:
                setAdapter(temperatureform, "Celsius", "Fahrenheit");
                ifrom = (String) fromDetails.getSelectedItem();
                rto = (String) toDetails.getSelectedItem();
                inp = Double.valueOf(fromInput.getText().toString());
                TemperatureConverter con = new TemperatureConverter();
                TemperatureConverter.Units fromUnit = TemperatureConverter.Units.fromString(ifrom);
                TemperatureConverter.Units toUnit = TemperatureConverter.Units.fromString(rto);
                out = con.TemperatureConvert(fromUnit,toUnit,inp);
                break;
            case 1:
                setAdapter(weightform, "Kilograms", "Grams");
                ifrom = (String) fromDetails.getSelectedItem();
                rto = (String) toDetails.getSelectedItem();
                inp = Double.valueOf(fromInput.getText().toString());
                WeightConverter converter = new WeightConverter();
                WeightConverter.Inus fromInus = WeightConverter.Inus.fromString(ifrom);
                WeightConverter.Inus toInus = WeightConverter.Inus.fromString(rto);
                out = converter.WeightConvert(fromInus, toInus, inp);
                break;

  final double finalOut = out;
        fromInput.addTextChangedListener(new TextWatcher() {
                @Override
                public void beforeTextChanged(CharSequence s, int start, int count, int after) {

                }

                @Override
                public void onTextChanged(CharSequence s, int start, int before, int count) {

                }

                @Override
                public void afterTextChanged(Editable s) {

                    if (!fromInput.getText().toString().equals(""))
                    {
                        toInput.setText(String.valueOf(finalOut));
                    }
                    else
                    {
                        toInput.setText("");
                    }

                }
            });


            return view;

    }


    private void setAdapter(String[] spinnerItems, String fromDefaultText, String toDefaultText) {
        fromDetails.setAdapter(new CustomSpinnerAdapter(getContext(), R.layout.spinner_item, spinnerItems, fromDefaultText));
        toDetails.setAdapter(new CustomSpinnerAdapter(getContext(), R.layout.spinner_item, spinnerItems, toDefaultText));
    }

    private void onInitVies(View view) {
        fromDetails = (Spinner) view.findViewById(R.id.fromSpinner);
        toDetails = (Spinner) view.findViewById(R.id.toSpinner);

        fromInput = (EditText) view.findViewById(R.id.fromInput);
        toInput = (EditText) view.findViewById(R.id.toInput);
    }

日志猫：

 Process: com.cloudicalabs.converters, PID: 8063
03-16 03:47:54.078 8063-8063/com.cloudicalabs.converters E/AndroidRuntime: java.lang.NumberFormatException: Invalid double: ""
03-16 03:47:54.078 8063-8063/com.cloudicalabs.converters E/AndroidRuntime:     at java.lang.StringToReal.invalidReal(StringToReal.java:63)
03-16 03:47:54.078 8063-8063/com.cloudicalabs.converters E/AndroidRuntime:     at java.lang.StringToReal.parseDouble(StringToReal.java:267)
03-16 03:47:54.078 8063-8063/com.cloudicalabs.converters E/AndroidRuntime:     at java.lang.Double.parseDouble(Double.java:301)
03-16 03:47:54.078 8063-8063/com.cloudicalabs.converters E/AndroidRuntime:     at java.lang.Double.valueOf(Double.java:338)
03-16 03:47:54.078 8063-8063/com.cloudicalabs.converters E/AndroidRuntime:     at com.cloudicalabs.converters.fragments.UniqueConverter.onCreateView(UniqueConverter.java:74)
03-16 03:47:54.078 8063-8063/com.cloudicalabs.converters E/AndroidRuntime:     at android.support.v4.app.Fragment.performCreateView(Fragment.java:1962)
03-16 03:47:54.078 8063-8063/com.cloudicalabs.converters E/AndroidRuntime:     at android.support.v4.app.FragmentManagerImpl.moveToState(FragmentManager.java:1067)
03-16 03:47:54.078 8063-8063/com.cloudicalabs.converters E/AndroidRuntime:     at android.support.v4.app.FragmentManagerImpl.moveToState(FragmentManager.java:1248)
03-16 03:47:54.078 8063-8063/com.cloudicalabs.converters E/AndroidRuntime:     at android.support.v4.app.BackStackRecord.run(BackStackRecord.java:738)

Answer 1

try {
   inp = Double.valueOf(fromInput.getText().toString());
} catch (NumberFormatException e) {
   inp = 0;
}

Answer 2

尝试替换此行

inp = Double.valueOf(fromInput.getText().toString());

与

inp = Double.parseDouble(fromInput.getText().toString());

Answer 3

@Override
public void afterTextChanged(Editable s) {

    if (!TextUtils.isEmpty(fromInput.getText())
    {
      String value=null;
        try {
            value=String.valueOf(Double.parseDouble(fromInput.getText().toString()));
            toInput.setText(value);
        } catch (NumberFormatException e) {
            e.printStackTrace();
            toInput.setText("");
        }
    }
    else
    {
        toInput.setText("");
    }
}

Answer 4

在此之前

inp = Double.valueOf(fromInput.getText().toString());

检查 fromInput 文本中的值是否有“”（空 - 即什么都没有：说像 .length == 0）然后你不应该解析它；而是通知用户输入一些值。 也将其放入 try catch。

Answer 5

您的问题是您要从中获取值的变量或资源为空，因此它说“”不是双重的。如果您从 fromInput.getText().toString() 获取值，则 fromInput 没有值，因此 null 不能转换为 double。