蓝牙打印机为每个新对象打印垃圾字符

Question

我正在参考P25 Demo Example使用蓝牙打印机打印收据。

一切正常。它也以定义的格式打印收据。但问题是每个新的String和StringBuilder对象都会打印很少的垃圾字符。

下面我要添加我的功能： -

private void printStruk() {
    String titleStr = "Receipt" + "\n\n";

    StringBuilder contentSb = new StringBuilder();

    contentSb.append("IDPEL     : 435353535435353" + "\n");
    contentSb.append("NAMA      : LORENSIUS WLT" + "\n");
    contentSb.append("TRF/DAYA  : 50/12244 VA" + "\n");
    contentSb.append("BL/TH     : 02/14" + "\n");
    contentSb.append("ST/MTR    : 0293232" + "\n");
    contentSb.append("RP TAG    : Rp. 100.000" + "\n");
    contentSb.append("JPA REF   :" + "\n");

    StringBuilder content2Sb = new StringBuilder();

    content2Sb.append("ADM BANK  : Rp. 1.600" + "\n");
    content2Sb.append("RP BAYAR  : Rp. 101.600,00" + "\n");


    byte[] titleByte    = Printer.printfont(titleStr, FontDefine.FONT_24PX,FontDefine.Align_CENTER, 
                            (byte)0x1A, PocketPos.LANGUAGE_ENGLISH);

    byte[] content1Byte = Printer.printfont(contentSb.toString(), FontDefine.FONT_24PX,FontDefine.Align_LEFT, 
                            (byte)0x1A, PocketPos.LANGUAGE_ENGLISH);


    byte[] content2Byte = Printer.printfont(content2Sb.toString(), FontDefine.FONT_24PX,FontDefine.Align_LEFT,  
                            (byte)0x1A, PocketPos.LANGUAGE_ENGLISH);

    byte[] totalByte    = new byte[titleByte.length + content1Byte.length +content2Byte.length];


    int offset = 0;
    System.arraycopy(titleByte, 0, totalByte, offset, titleByte.length);
    offset += titleByte.length;

    System.arraycopy(content1Byte, 0, totalByte, offset, content1Byte.length);
    offset += content1Byte.length;

    System.arraycopy(content2Byte, 0, totalByte, offset, content2Byte.length);
    offset += content2Byte.length;

    byte[] senddata = PocketPos.FramePack(PocketPos.FRAME_TOF_PRINT, totalByte, 0, totalByte.length);

    sendData(senddata); 
}

在上面的代码中，它在文件的中心打印标题字符串收据，但在此之前它还会打印一些垃圾字符。