private POSPrinter posprinter = initUSBPrinter("POSPrinter1");
private POSPrinter posprinter2 = initUSBPrinter("POSPrinter2");

private static POSPrinter initUSBPrinter(String printerName) {
    POSPrinter ptr = new POSPrinter();
    try {
        ptr.open(printerName);
        ptr.claim(1000);
        ptr.setDeviceEnabled(true);
    } catch (JposException e) {
        e.printStackTrace();
    }
    return ptr ;
}