Better way to Format Currency Input editText?

I tested your method, but it fails when I use great numbers... I created this:

private String current = "";
@Override
public void onTextChanged(CharSequence s, int start, int before, int count) {
    if(!s.toString().equals(current)){
       [your_edittext].removeTextChangedListener(this);

       String cleanString = s.toString().replaceAll("[$,.]", "");
                
       double parsed = Double.parseDouble(cleanString);
       String formatted = NumberFormat.getCurrencyInstance().format((parsed/100));
                    
       current = formatted;
       [your_edittext].setText(formatted);
       [your_edittext].setSelection(formatted.length());
       
       [your_edittext].addTextChangedListener(this);
    }
}

Kotlin variant:

private var current: String = ""

         override fun onTextChanged(
            s: CharSequence,
            start: Int,
            before: Int,
            count: Int
        ) {
            if (s.toString() != current) {
                discount_amount_edit_text.removeTextChangedListener(this)

                val cleanString: String = s.replace("""[$,.]""".toRegex(), "")

                val parsed = cleanString.toDouble()
                val formatted = NumberFormat.getCurrencyInstance().format((parsed / 100))

                current = formatted
                discount_amount_edit_text.setText(formatted)
                discount_amount_edit_text.setSelection(formatted.length)

                discount_amount_edit_text.addTextChangedListener(this)
            }
        }

Here is my custom CurrencyEditText

import android.content.Context;import android.graphics.Rect;import android.text.Editable;import android.text.InputFilter;import android.text.InputType;import android.text.TextWatcher;
import android.util.AttributeSet;import android.widget.EditText;import java.math.BigDecimal;import java.math.RoundingMode;
import java.text.DecimalFormat;import java.text.DecimalFormatSymbols;
import java.util.Locale;

/**
 * Some note <br/>
 * <li>Always use locale US instead of default to make DecimalFormat work well in all language</li>
 */
public class CurrencyEditText extends android.support.v7.widget.AppCompatEditText {
    private static String prefix = "VND ";
    private static final int MAX_LENGTH = 20;
    private static final int MAX_DECIMAL = 3;
    private CurrencyTextWatcher currencyTextWatcher = new CurrencyTextWatcher(this, prefix);

    public CurrencyEditText(Context context) {
        this(context, null);
    }

    public CurrencyEditText(Context context, AttributeSet attrs) {
        this(context, attrs, android.support.v7.appcompat.R.attr.editTextStyle);
    }

    public CurrencyEditText(Context context, AttributeSet attrs, int defStyleAttr) {
        super(context, attrs, defStyleAttr);
        this.setInputType(InputType.TYPE_CLASS_NUMBER | InputType.TYPE_NUMBER_FLAG_DECIMAL);
        this.setHint(prefix);
        this.setFilters(new InputFilter[] { new InputFilter.LengthFilter(MAX_LENGTH) });
    }

    @Override
    protected void onFocusChanged(boolean focused, int direction, Rect previouslyFocusedRect) {
        super.onFocusChanged(focused, direction, previouslyFocusedRect);
        if (focused) {
            this.addTextChangedListener(currencyTextWatcher);
        } else {
            this.removeTextChangedListener(currencyTextWatcher);
        }
        handleCaseCurrencyEmpty(focused);
    }

    /**
     * When currency empty <br/>
     * + When focus EditText, set the default text = prefix (ex: VND) <br/>
     * + When EditText lose focus, set the default text = "", EditText will display hint (ex:VND)
     */
    private void handleCaseCurrencyEmpty(boolean focused) {
        if (focused) {
            if (getText().toString().isEmpty()) {
                setText(prefix);
            }
        } else {
            if (getText().toString().equals(prefix)) {
                setText("");
            }
        }
    }

    private static class CurrencyTextWatcher implements TextWatcher {
        private final EditText editText;
        private String previousCleanString;
        private String prefix;

        CurrencyTextWatcher(EditText editText, String prefix) {
            this.editText = editText;
            this.prefix = prefix;
        }

        @Override
        public void beforeTextChanged(CharSequence s, int start, int count, int after) {
            // do nothing
        }

        @Override
        public void onTextChanged(CharSequence s, int start, int before, int count) {
            // do nothing
        }

        @Override
        public void afterTextChanged(Editable editable) {
            String str = editable.toString();
            if (str.length() < prefix.length()) {
                editText.setText(prefix);
                editText.setSelection(prefix.length());
                return;
            }
            if (str.equals(prefix)) {
                return;
            }
            // cleanString this the string which not contain prefix and ,
            String cleanString = str.replace(prefix, "").replaceAll("[,]", "");
            // for prevent afterTextChanged recursive call
            if (cleanString.equals(previousCleanString) || cleanString.isEmpty()) {
                return;
            }
            previousCleanString = cleanString;

            String formattedString;
            if (cleanString.contains(".")) {
                formattedString = formatDecimal(cleanString);
            } else {
                formattedString = formatInteger(cleanString);
            }
            editText.removeTextChangedListener(this); // Remove listener
            editText.setText(formattedString);
            handleSelection();
            editText.addTextChangedListener(this); // Add back the listener
        }

        private String formatInteger(String str) {
            BigDecimal parsed = new BigDecimal(str);
            DecimalFormat formatter =
                    new DecimalFormat(prefix + "#,###", new DecimalFormatSymbols(Locale.US));
            return formatter.format(parsed);
        }

        private String formatDecimal(String str) {
            if (str.equals(".")) {
                return prefix + ".";
            }
            BigDecimal parsed = new BigDecimal(str);
            // example pattern VND #,###.00
            DecimalFormat formatter = new DecimalFormat(prefix + "#,###." + getDecimalPattern(str),
                    new DecimalFormatSymbols(Locale.US));
            formatter.setRoundingMode(RoundingMode.DOWN);
            return formatter.format(parsed);
        }

        /**
         * It will return suitable pattern for format decimal
         * For example: 10.2 -> return 0 | 10.23 -> return 00, | 10.235 -> return 000
         */
        private String getDecimalPattern(String str) {
            int decimalCount = str.length() - str.indexOf(".") - 1;
            StringBuilder decimalPattern = new StringBuilder();
            for (int i = 0; i < decimalCount && i < MAX_DECIMAL; i++) {
                decimalPattern.append("0");
            }
            return decimalPattern.toString();
        }

        private void handleSelection() {
            if (editText.getText().length() <= MAX_LENGTH) {
                editText.setSelection(editText.getText().length());
            } else {
                editText.setSelection(MAX_LENGTH);
            }
        }
    }
}

Use it in XML like

 <...CurrencyEditText
        android:layout_width="match_parent"
        android:layout_height="wrap_content"
        />

You should edit 2 constant below for suitable for your project

private static String prefix = "VND ";
private static final int MAX_DECIMAL = 3;

Demo on github

Based on some of the above answers I created a MoneyTextWatcher which you'd use as follows:

priceEditText.addTextChangedListener(new MoneyTextWatcher(priceEditText));

and here's the class:

public class MoneyTextWatcher implements TextWatcher {
    private final WeakReference<EditText> editTextWeakReference;

    public MoneyTextWatcher(EditText editText) {
        editTextWeakReference = new WeakReference<EditText>(editText);
    }

    @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 editable) {
        EditText editText = editTextWeakReference.get();
        if (editText == null) return;
        String s = editable.toString();
        if (s.isEmpty()) return;
        editText.removeTextChangedListener(this);
        String cleanString = s.replaceAll("[$,.]", "");
        BigDecimal parsed = new BigDecimal(cleanString).setScale(2, BigDecimal.ROUND_FLOOR).divide(new BigDecimal(100), BigDecimal.ROUND_FLOOR);
        String formatted = NumberFormat.getCurrencyInstance().format(parsed);
        editText.setText(formatted);
        editText.setSelection(formatted.length());
        editText.addTextChangedListener(this);
    }
}