java - 获取 numberFormatException 无效 double 值

Question

我将一个数值放入 EditText 中。假设我得到输入首先说“输入”。然后对输入执行toString()。然后parseDouble()。假设结果是输入*2。所以我然后在 EditText 中进行设置。假设，

          package com.hasibshovon.unitconverter;

         import android.app.Activity;
      import android.os.Bundle;
       import android.view.Menu;
      import android.view.View;
      import android.widget.AdapterView;
       import android.widget.AdapterView.OnItemSelectedListener;
        import android.widget.ArrayAdapter;
    import android.widget.EditText;
     import android.widget.Spinner;

         public class MainActivity extends Activity {
// data source
private static String[] types = { "Angle", "Area", "Bits&Bytes", "Density",
        "Electric Current", "Energy", "Force", "Length", "Mass", "Power",
        "Pressure", "Speed", "Temperature", "Time", "Volume" };

private static String[] AngleUnits = { "Degree", "Radian", "Grad", "Gon",
        "Minute", "Second", "SIgn", "Mil", "Revolution", "Circle", "Turn",
        "Quadrant", "Right", "Triangle", "Sextant" };

private static String[] AreaUnits = { "SquareMeter", "SquareKilometer",
        "SquareHectometer", "SquareDekameter", "SquareDecimeter",
        "SquareCentimeter", "SquareMilimeter", "SquareMicrometer",
        "SquareNanometer", "Hectare", "SquareMile", "SquareYard",
        "SquareFoot", "SquareInch", "Acre" };

private static String[] BitsBytesUnits = { "bit", "byte", "kilobit",
        "kilobyte", "megabit", "megabyte", "gigabit", "gigabyte",
        "terabit", "terabyte", "petabit", "petabyte", "exabit", "exabyte" };

private static String[] DensityUnits = { "kilogram/cubicmeter",
        "kilogram/cubiccentimeter", "gram/cubicmeter",
        "gram/cubiccentimeter", "gram/cubicmilimeter",
        "miligram/cubicmeter", "miligram/cubiccentimeter",
        "miligram/cubicmilimeter", "exagram/liter", "petagram/liter",
        "teragram/liter", "gigagram/liter", "meggram/liter",
        "kilogram/liter", "hectogram/liter", "decagram/liter",
        "gram/liter", "decigram/liter", "centigram/liter",
        "miligram/liter", "microgram/liter", "nanogram/liter",
        "picogram/liter" };

private static String[] CurrentUnits = { "ampere", "kiloampere",
        "miliampere", "biot", "abaampere", "stataampere" };

private static String[] EnergyUnits = { "joule", "gigajoule", "megajoule",
        "kilojoule", "milijoule", "microjoule", "nanojoule", "attojoule" };

private static String[] ForceUnits = { "newton", "dyne", "joul/meter",
        "joul/centimeter", "gram-force", "kilogram-force", "kip-force",
        "pond", "kilo-pond" };

private static String[] LengthUnits = { "meter", "exameter", "terameter",
        "petameter", "gigameter", "megameter", "kilometer", "hectometer",
        "dekameter", "decimeter", "centimeter", "milimeter", "micrometer",
        "nanometer", "picometer", "femtometer", "attometer" };

private static String[] MassUnits = { "gram", "kilogram", "miligram",
        "dalton", "pound", "ounce", "ton", "quarter", "grain" };

private static String[] PowerUnits = { "watt", "megawatt", "horsepower",
        "kilocalorie", "joul/hour", "kilojoul/hour", "joul/second" };

private static String[] PressureUnits = { "pascal", "newton/squaremeter",
        "bar", "kilogram-force/squaremeter", "ton-force/squarefoot",
        "poundal/squarefoot", "atmosphere(atm)" };

private static String[] SpeedUnits = { "meter/second", "kilometer/hour",
        "foot/hour", "yard/hour", "mile/hour", "mile/second", "knot" };

private static String[] TemperatureUnits = { "kelvin", "celsius",
        "farenheit", "rankine", "reaumur" };

private static String[] TimeUnits = { "second", "milisecond",
        "microsecond", "nanosecond", "minute", "hour", "day", "week",
        "month", "year", "decade", "century", "millenium" };

private static String[] VolumeUnits = { "cubicmeter", "cubickilometer",
        "cubiccentimeter", "liter", "cc", "barrel", "cup", "cubicmile",
        "cubicfoot", "cubicyard", "cubicinch", "acre-foot" };

private Spinner spnUnitTypes;
private Spinner spnFromUnit;
private Spinner spnToUnit;
private EditText etFrom;
private EditText etTo;
public String value1, value2;
public double fromDouble;
public double result;
// adapters
ArrayAdapter<String> adaptUnittype;
ArrayAdapter<String> adaptFrom;
ArrayAdapter<String> adaptTo;

// private OnItemSelectedListener UnitLisetener;

@Override
protected void onCreate(Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);
    setContentView(R.layout.activity_main);
    // spnUnitTypes.setOnItemSelectedListener(UnitLisetener);
    etFrom = (EditText) findViewById(R.id.etConvertFrom);

    etTo = (EditText) findViewById(R.id.etToResult);

    // initialize view
    spnUnitTypes = (Spinner) findViewById(R.id.spnUnitType);
    spnFromUnit = (Spinner) findViewById(R.id.spnFromUnit);
    spnToUnit = (Spinner) findViewById(R.id.spnToUnit);

    // initialize adapter
    adaptUnittype = new ArrayAdapter<String>(MainActivity.this,
            android.R.layout.simple_spinner_item, types);

    // bind adapter and view
    spnUnitTypes.setAdapter(adaptUnittype);
    spnUnitTypes.setOnItemSelectedListener(new OnItemSelectedListener() {

        @Override
        public void onItemSelected(AdapterView<?> arg0, View arg1,
                int postion, long arg3) {
            if (types[postion].equals("Time")) {

                adaptFrom = new ArrayAdapter<String>(MainActivity.this,
                        android.R.layout.simple_spinner_item, TimeUnits);
                adaptTo = new ArrayAdapter<String>(MainActivity.this,
                        android.R.layout.simple_spinner_item, TimeUnits);

            } else if (types[postion].equals("Mass")) {

                adaptFrom = new ArrayAdapter<String>(MainActivity.this,
                        android.R.layout.simple_spinner_item, MassUnits);
                adaptTo = new ArrayAdapter<String>(MainActivity.this,
                        android.R.layout.simple_spinner_item, MassUnits);

            } else if (types[postion].equals("Angle")) {

                adaptFrom = new ArrayAdapter<String>(MainActivity.this,
                        android.R.layout.simple_spinner_item, AngleUnits);
                adaptTo = new ArrayAdapter<String>(MainActivity.this,
                        android.R.layout.simple_spinner_item, AngleUnits);

            } else if (types[postion].equals("Area")) {

                adaptFrom = new ArrayAdapter<String>(MainActivity.this,
                        android.R.layout.simple_spinner_item, AreaUnits);
                adaptTo = new ArrayAdapter<String>(MainActivity.this,
                        android.R.layout.simple_spinner_item, AreaUnits);

            } else if (types[postion].equals("Density")) {

                adaptFrom = new ArrayAdapter<String>(MainActivity.this,
                        android.R.layout.simple_spinner_item, DensityUnits);
                adaptTo = new ArrayAdapter<String>(MainActivity.this,
                        android.R.layout.simple_spinner_item, DensityUnits);

            } else if (types[postion].equals("Bits&Bytes")) {

                adaptFrom = new ArrayAdapter<String>(MainActivity.this,
                        android.R.layout.simple_spinner_item,
                        BitsBytesUnits);
                adaptTo = new ArrayAdapter<String>(MainActivity.this,
                        android.R.layout.simple_spinner_item,
                        BitsBytesUnits);

            } else if (types[postion].equals("Electric Current")) {

                adaptFrom = new ArrayAdapter<String>(MainActivity.this,
                        android.R.layout.simple_spinner_item, CurrentUnits);
                adaptTo = new ArrayAdapter<String>(MainActivity.this,
                        android.R.layout.simple_spinner_item, CurrentUnits);

            } else if (types[postion].equals("Energy")) {

                adaptFrom = new ArrayAdapter<String>(MainActivity.this,
                        android.R.layout.simple_spinner_item, EnergyUnits);
                adaptTo = new ArrayAdapter<String>(MainActivity.this,
                        android.R.layout.simple_spinner_item, EnergyUnits);

            } else if (types[postion].equals("Force")) {

                adaptFrom = new ArrayAdapter<String>(MainActivity.this,
                        android.R.layout.simple_spinner_item, ForceUnits);
                adaptTo = new ArrayAdapter<String>(MainActivity.this,
                        android.R.layout.simple_spinner_item, ForceUnits);

            } else if (types[postion].equals("Length")) {

                adaptFrom = new ArrayAdapter<String>(MainActivity.this,
                        android.R.layout.simple_spinner_item, LengthUnits);
                adaptTo = new ArrayAdapter<String>(MainActivity.this,
                        android.R.layout.simple_spinner_item, LengthUnits);

            } else if (types[postion].equals("Power")) {

                adaptFrom = new ArrayAdapter<String>(MainActivity.this,
                        android.R.layout.simple_spinner_item, PowerUnits);
                adaptTo = new ArrayAdapter<String>(MainActivity.this,
                        android.R.layout.simple_spinner_item, PowerUnits);

            } else if (types[postion].equals("Pressure")) {

                adaptFrom = new ArrayAdapter<String>(MainActivity.this,
                        android.R.layout.simple_spinner_item, PressureUnits);
                adaptTo = new ArrayAdapter<String>(MainActivity.this,
                        android.R.layout.simple_spinner_item, PressureUnits);

            } else if (types[postion].equals("Speed")) {

                adaptFrom = new ArrayAdapter<String>(MainActivity.this,
                        android.R.layout.simple_spinner_item, SpeedUnits);
                adaptTo = new ArrayAdapter<String>(MainActivity.this,
                        android.R.layout.simple_spinner_item, SpeedUnits);

            } else if (types[postion].equals("Temperature")) {

                adaptFrom = new ArrayAdapter<String>(MainActivity.this,
                        android.R.layout.simple_spinner_item,
                        TemperatureUnits);
                adaptTo = new ArrayAdapter<String>(MainActivity.this,
                        android.R.layout.simple_spinner_item,
                        TemperatureUnits);
            }
            spnFromUnit.setAdapter(adaptFrom);
            spnToUnit.setAdapter(adaptTo);
            spnFromUnit
                    .setOnItemSelectedListener(new OnItemSelectedListener() {

                        @Override
                        public void onItemSelected(AdapterView<?> parent,
                                View arg1, int pos, long arg3) {
                            Object item = parent.getItemAtPosition(pos);
                            value1 = item.toString();
                        }

                        @Override
                        public void onNothingSelected(AdapterView<?> arg0) {
                            // TODO Auto-generated method stub

                        }

                    });
            spnToUnit
                    .setOnItemSelectedListener(new OnItemSelectedListener() {

                        @Override
                        public void onItemSelected(AdapterView<?> parent,
                                View arg1, int pos, long arg3) {
                            Object item1 = parent.getItemAtPosition(pos);
                            value2 = item1.toString();

                        }

                        @Override
                        public void onNothingSelected(AdapterView<?> arg0) {
                            // TODO Auto-generated method stub

                        }

                    });

        }

        @Override
        public void onNothingSelected(AdapterView<?> arg0) {

        }
    });
    String fromstr = etFrom.getText().toString();
    double fromDouble = Double.parseDouble(fromstr);

}


public void convert(View v) {
    if (value1.equals("Degree") && value2.equals("Radian")) {
        etTo.setText(String.valueOf(fromDouble*2));
    }
}

@Override
public boolean onCreateOptionsMenu(Menu menu) {
    // Inflate the menu; this adds items to the action bar if it is present.
    getMenuInflater().inflate(R.menu.main, menu);
    return true;
}

}

Answer 1

您的输入似乎为空或不包含要解析的数字。通过使用 try/catch 记录或打印出值来尝试调试

String fromstr = etFrom.getText().toString();
try {
      double fromDouble = Double.parseDouble(fromstr);
} catch (NumberFormatException e) {
    System.out.println(fromstr)
}