How to change the color of a particular string in edit text on the fly??-Android

Question

In my app, I want the users to give their answers in the form of text through edit text. So for the correct answer I want the letters to turn green (or red for incorrect) on the fly while typing.

For example, if the answer is DOG, I want the the text to turn green if the user types DOG dynamically. Even if the the first letter he types is D then I want the text color to be green. Only when the user's input text is not correct do I want it to be red. The text color should change on the fly while typing.

Answer 1

Create EditText and call addTextChangedListener for it supplying custom TextWatcher where you mostly need to override its onTextChanged.

In this method change your text color according to your logic.

Snapshot :

    mEditBox = (EditText) findViewById(R.id.my_edit_box_id);
    mEditBox.addTextChangedListener(new TextWatcher() {

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

            String currentText = mEditBox.getText().toString();
            // highligt correct answer in green
            if ("DOG".startsWith(currentText)) { // user starts typing "DOG"
                mEditBox.setTextColor(Color.GREEN);
            } else {
                mEditBox.setTextColor(Color.RED); // incorrect input
            }

        }

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

        }

        @Override
        public void afterTextChanged(Editable s) {

        }
    });