How print invoice receipt using bluetooth thermal printer

you can use this

void printLine(String txt, char type){
    byte[] format = { 27, 33, 0 };
    byte[] arrayOfByte1 = { 27, 33, 0 };

    if (type == 'b') {
        format[2] = ((byte) (0x8 | arrayOfByte1[2])); //BOLD
    }
    if (type == 'h') {
        format[2] = ((byte) (0x10 | arrayOfByte1[2])); //HEIGHT
    }
    if (type == 'w') {
        format[2] = ((byte) (0x20 | arrayOfByte1[2])); //WIDTH
    }
    if (type == 'u') {
        format[2] = ((byte) (0x80 | arrayOfByte1[2])); //UNDERLINE
    }
    if (type == 's') {
        format[2] = ((byte) (0x1 | arrayOfByte1[2])); //SMALL
    }
    mService.write(format);
    mService.sendMessage(txt,"GBK");
}

credit goes to Leonardo Sapuy and his original q/a Format text in bluetooth printer and thanks to Murtaza Khursheed Hussain for sending me to it

I have found the following image over the internet for Text Alignment. Hope it helps