instead of using

while(Serial.available() > 0)
  {
     incomingByte= Serial.read();
     stringOne = String(stringOne + String(incomingByte));
  }

Use the following to cast them to character

while(Serial.available() > 0)
  {
     char incomingByte= Serial.read();
     stringOne.concat(incomingByte));
  }
Serial.println(stringOne);
stringOne="";

Instead of using:

while(Serial.available() > 0)
  {
     incomingByte= Serial.read();
     stringOne = String(stringOne + String(incomingByte));
  }

Use the following to cast them to character:

while(Serial.available() > 0)
  {
     char incomingByte= Serial.read();
     stringOne.concat(incomingByte));
  }
Serial.println(stringOne);
stringOne="";

instead of using

while(Serial.available() > 0)

{ incomingByte= Serial.read(); stringOne = String(stringOne + String(incomingByte));

}

Use the following to cast them to character

while(Serial.available() > 0)

{ char incomingByte= Serial.read(); stringOne.concat(incomingByte));

} Serial.println(stringOne); stringOne="";

instead of using

while(Serial.available() > 0)
  {
     incomingByte= Serial.read();
     stringOne = String(stringOne + String(incomingByte));
  }

Use the following to cast them to character

while(Serial.available() > 0)
  {
     char incomingByte= Serial.read();
     stringOne.concat(incomingByte));
  }
Serial.println(stringOne);
stringOne="";