negative numbers input filter

Question

I want to restrict the edittext input to -99.99. But my inputfilter prevents me to enter "-". Could you guys help me to check what's wrong with it.

private int min, max;

public InputFilterMinMax(int min, int max) {
    this.min = min;
    this.max = max;
}

public InputFilterMinMax(String min, String max) {
    this.min = Integer.parseInt(min);
    this.max = Integer.parseInt(max);
}

@Override
public CharSequence filter(CharSequence source, int start, int end, Spanned dest, int dstart, int dend) {
    try {
        double input = Double.valueOf(dest.toString() + source.toString());
        if (isInRange(min, max, input))
            return null;
    } catch (NumberFormatException nfe) { }
    return "";
}

private boolean isInRange(int a, int b, double c) {
    return b > a ? c >= a && c <= b : c >= b && c <= a;
}

mainactivity

text.setFilters(new InputFilter[]{new InputFilterMinMax("-99", "99")});

xml

android:inputType="numberDecimal|numberSigned"
        android:digits="0123456789+-."

thanks :)

Answer 1

Try this!

Min max filter

 public class MinMaxFilter  implements InputFilter {
    private int min,max;
    Context context;

    //contructor
    public MinMaxFilter(int min, int max, Context context){
        this.min = min;
        this.max = max;
        this.context = context;
    }

    @Override
    public CharSequence filter(CharSequence source, int start, int end, Spanned dest, int dStart, int dEnd) {
        //code for filter input between -25 to 100
        //get current number
        String newValue = dest.subSequence(0,dStart)
                + source.subSequence(start,end).toString()
                + dest.subSequence(dEnd,dest.length());

        //need to define because prevent error in null exception in line 40
        int input = 0;

        try{
            //if first input is "-" = false
            //if dest variabel has 0 length = false
            if(!(dest.length() == 0) || !newValue.trim().equals("-")){
                input = Integer.parseInt(newValue);
            }

            //if input <= max and input >= min it will return true
            if(isInRange(min,max,input)){
                //if true keyboard can click
                return null;
            }
        }catch (NumberFormatException ex){
            ex.printStackTrace();
        }

        //if input doesn't complete requirement it will prevent keyboard input to edit text
        return "";
    }

    //if input <= max and input >= min it will return true

    private boolean isInRange(int min, int max, int input)
    {
        return input >= min && input <= max;
    }
}

set your edit text's filter with minmax filter

//your edit text
    temperatureET = findViewById(R.id.editTextNumber);
    temperatureET.setFilters(new InputFilter[]{ new MinMaxFilter(-25,100,getApplicationContext())});

BTW, this is my first answer in stackoverflow. So i'am sorry if this answer is so ugly.

Answer 2

Then you can change the data type to string to allow it, followed by extracting the relevant numbers (depending how clean coded you want).

At the moment, it is Double...so it wouldn't take negative.

Answer 3

Replace your filter method with below code-

  @Override
public CharSequence filter(CharSequence source, int start, int end, Spanned dest, int dStart, int dEnd) {
    try {
        // Remove the string out of destination that is to be replaced
        String newVal = dest.toString().substring(0, dStart) + dest.toString().substring(dEnd, dest.toString().length());
        newVal = newVal.substring(0, dStart) + source.toString() + newVal.substring(dStart, newVal.length());
        if (newVal.equals("-") || newVal.equals(".")){
            if(end == 0){
                return "";
            }
            return newVal;
        }
        double input = Double.parseDouble(newVal);

        if (isInRange(minValue, maxValue, input)) {
            return null;
        }
    } catch (NumberFormatException e) {
        e.printStackTrace();
    }
    return "";
}