Android EditText with number format input

Some applications require formatting the EditText's value while typing. I.E., a number that needs to be formatted with decimal and thousands separators.

We've created a little helper class implementing TextWatcher to do just that.

import java.text.DecimalFormat;
import java.text.ParseException;

import android.text.Editable;
import android.text.TextWatcher;
import android.widget.EditText;

public class NumberTextWatcher implements TextWatcher {
    
    private DecimalFormat df;
    private DecimalFormat dfnd;
    private boolean hasFractionalPart;
    
    private EditText et;
    
    public NumberTextWatcher(EditText et)
    {
        df = new DecimalFormat("#,###.##");
        df.setDecimalSeparatorAlwaysShown(true);
        dfnd = new DecimalFormat("#,###");
        this.et = et;
        hasFractionalPart = false;
    }
    
    @SuppressWarnings("unused")
    private static final String TAG = "NumberTextWatcher";

    @Override
    public void afterTextChanged(Editable s)
    {
        et.removeTextChangedListener(this);
        
        try {
            int inilen, endlen;
            inilen = et.getText().length();
            
            String v = s.toString().replace(String.valueOf(df.getDecimalFormatSymbols().getGroupingSeparator()), "");
            Number n = df.parse(v);
            int cp = et.getSelectionStart();
            if (hasFractionalPart) {
                et.setText(df.format(n));
            } else {
                et.setText(dfnd.format(n));
            }
            endlen = et.getText().length();
            int sel = (cp + (endlen - inilen));
            if (sel > 0 && sel <= et.getText().length()) {
                et.setSelection(sel);
            } else {
                // place cursor at the end?
                et.setSelection(et.getText().length() - 1);
            }
        } catch (NumberFormatException nfe) {
            // do nothing?
        } catch (ParseException e) {
            // do nothing?
        }
        
        et.addTextChangedListener(this);
    }

    @Override
    public void beforeTextChanged(CharSequence s, int start, int count, int after)
    {
    }

    @Override
    public void onTextChanged(CharSequence s, int start, int before, int count)
    {
        if (s.toString().contains(String.valueOf(df.getDecimalFormatSymbols().getDecimalSeparator())))
        {
            hasFractionalPart = true;
        } else {
            hasFractionalPart = false;
        }
    }

}

To use it, all you need to do is add a TextChangedListener to the EditText component.

editText.addTextChangedListener(new NumberTextWatcher(editText));

You can get the source code directly from GitHub.