当用户在编辑文本中输入金额时，用金额替换 0 的最佳方法

Question

I am working on app where an edittext is having $0 as pre-defined text. Zero is editable. But as soon as user enters an amount like $80, its showing $080. I am using textwatcher to non deleted $ and replaced at time of printing value.

How can i achieve the output as $80 when user is typing an amount

preset value - $0 after typing $80, Output = $080 Expected = $80

Thanks in advance.

   amountEdittext.setText("$0");
    Selection.setSelection(amountEdittext.getText(), 
 amountEdittext.getText().length());
    amountEdittext.addTextChangedListener(new TextWatcher() {

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

        }

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

        @Override
        public void afterTextChanged(Editable s) {
            if (!s.toString().startsWith("$")) {
                amountEdittext.setText("$");
                Selection.setSelection(amountEdittext.getText(), amountEdittext.getText().length());

            }

        }
    });

Answer 1

Instead of using the text property you should HINT

amountEdittext.setHint("$0");

you will no longer require to any other code. and keep the text blank you can then add validation to check for empty text.

you can change the hint when it has focus using setOnFocusChangeListener()

Answer 2

Just pass the Edittext clear. When user clicks on edittext just remove the value

amountEdittext.setOnClickListener(new View.OnClickListener() {
    @Override
    public void onClick(View v) {
        amountEdittext.getText().clear();
    }
});

or Something like this

@Override
    public void afterTextChanged(Editable s) {
        String myValue = "$"+amountEdittext.getText().toString();
    }

Answer 3

Better use a InputFilter than using TextWatcher . Since you've the $ sign better to remove it from the EditText and use one TextView along with EditText horizontally. So that you can get rid of the dollar sign

class DecimalDigitsInputFilter(digitsBeforeZero: Int, digitsAfterZero: Int) : InputFilter {
private val mPattern: Pattern

init {
    mPattern =
        Pattern.compile("[0-9]{0," + (digitsBeforeZero ) + "}+((\\.[0-9]{0," + (digitsAfterZero ) + "})?)||(\\.)?")
}

override fun filter(
    source: CharSequence?,
    start: Int,
    end: Int,
    dest: Spanned?,
    dstart: Int,
    dend: Int
): CharSequence? {

    if (source != null && dest != null) {
        val replacement = source.subSequence(start, end).toString()
        val newVal = (dest.subSequence(0, dstart).toString() + replacement
                + dest.subSequence(dend, dest.length).toString())
        val matcher = mPattern.matcher(newVal)
        if (matcher.matches())
            return null

        return if (TextUtils.isEmpty(source))
            dest.subSequence(dstart, dend)
        else
            return ""
    }
    return ""
    }
}

Answer 4

I have just realized what you are doing, Selection.setSelection moves the cursor to the end of text in the edittext,so that will be after zero.

So, here is a solution that i think would work;

    amountEdittext.setText("$0");
    amountEdittext.setOnFocusChange(View view, boolean b) {
        if (b && amountEdittext.getText().toString().matches("^\\$0$")) {
            amountEdittext.setText("$");
            Selection.setSelection(amountEdittext.getText(), amountEdittext.getText().length());
        } else {
            Selection.setSelection(amountEdittext.getText(), amountEdittext.getText().length());
        }
    }

Answer 5

This should solve your question.

    amountEdittext.addTextChangedListener(new TextWatcher() {
        @Override
        public void beforeTextChanged(CharSequence charSequence, int i, int i1, int i2) {
        }

        @Override
        public void onTextChanged(CharSequence charSequence, int i, int i1, int i2) {
        }

        @Override
        public void afterTextChanged(Editable editable) {
            if (editable.length() > 2) {
                for (int i = 0; i < editable.length() - 1; i++) {
                    if (editable.charAt(i) == '$' && editable.charAt(i + 1) == '0') {
                        editable.delete(i + 1, i + 2);
                    }
                }
            }
        }
    });
}