SpannableStringBuilder builder = new SpannableStringBuilder();
        String red = "I am RED ";
        SpannableString redSpannable= new SpannableString(red);
        redSpannable.setSpan(new ForegroundColorSpan(Color.RED), 0, red.length(), 0);
        builder.append(redSpannable);

        EditText et = (EditText)findViewById(R.id.editText1);
        et.setText(builder, BufferType.SPANNABLE);

        int position = et.length();
        Editable etext = et.getText();
        Selection.setSelection(etext, position);