Can't found symbol error

Question

After compiling the following code .I am getting four errors if I am using
package.If I am not using any package than code compiled successfully.
So can anyone tell me what mistake I had done.
package smspack;
import java.io.*;
import java.rmi.*;
import java.util.*;
import javax.comm.*;
class Port {
private static String portName;
private static SerialPort port;
private static OutputStreamWriter out;
private static InputStreamReader in;
static final String COMPORT = "COM1";
//public static JTextArea ta = new JTextArea(40, 100);
private static String number;
private static String message;
private static boolean numbertype; // national or international dialing number
/** open the connection via the serial line
* @throws Exception
public static void open() throws Exception {
//----- open the connection via the serial line
try {
CommPortIdentifier portId = CommPortIdentifier.getPortIdentifier(SMS.COMPORT);
port = (SerialPort)portId.open("SMS Transceiver", 10); // open port
// set parameter for serial port
port.setSerialPortParams(19200, SerialPort.DATABITS_8, SerialPort.STOPBITS_1, SerialPort.PARITY_NONE);
out = new OutputStreamWriter(port.getOutputStream(), "ISO-8859-1");
in = new InputStreamReader(port.getInputStream(), "ISO-8859-1");
System.out.println("open port\n"); // for debugging
} // try
catch (Exception e) {
SMS.showText("could not open port:" + e);
System.exit(0);
} // catch
} // open
/** sends an AT command to ME and receives the answer of the ME
* @param atcommand AT command for the GSM Modem
* @return answer string of the ME
* @throws java.rmi.RemoteException
public static String sendAT(String atcommand) throws java.rmi.RemoteException {
String s="";
try {
Thread.sleep(300); // wait 300 msec [Timing]
writeln(atcommand); // send AT command to ME
Thread.sleep(300); // wait 300 msec [Timing]
s = read(); // get response from ME
Thread.sleep(300); // wait 300 msec [Timing]
} // try
catch (Exception e) {
SMS.showText("ERROR: send AT command failed; " + "Command: " + atcommand + "; Answer: " + s + " " + e);
} // catch
return s;
} // sendAT
/** write a string to the output buffer
* @param s string for the serial output buffer
* @throws Exception
public static void write(String s) throws Exception {
out.write(s);
out.flush();
} // write
/** write a character to the output buffer
* @param s character for the serial output buffer
* @throws Exception
public static void write(char[] s) throws Exception {
out.write(s);
out.flush();
} // write
/** write a string with CR at the end to the output buffer
* @param s string for the serial output buffer
* @throws Exception
public static void writeln(String s) throws Exception {
out.write(s);
out.write('\r');
out.flush();
System.out.println("write port: " + s + "\n"); // for debugging
} // writeln
/** receives a character string from the serial line
* @return received character string from ME
* @throws Exception
* Remark: Some mobile phones don't send one byte immediate after the other
* byte to the PC. Thus it is necessary to check (about) 5 times after
* a delay that all bytes are received. It is also important to collect
* the bytes not too fast, because this can result in some lost bytes.
public static String read() throws Exception {
int n, i;
char c;
String answer = new String("");
do {                              // wait until the first byte is received
Thread.sleep(100); // wait at least 100 msec [Timing]
} while (in.ready() == false);
for (i = 0; i < 10; i++) {         // look 5 times for character string to receive
//----- collect all characters from the serial line
while (in.ready()) {            // there is a byte available
n = in.read(); // get the byte from the serial line
if (n != -1) {                // one byte received
c = (char)n; // convert the received integer to a character
answer = answer + c; // collect the characters from the serial line
Thread.sleep(1); // wait 1 msec between every collected byte from the mobile phone [Timing]
} // if
else break; // no more bytes available
} // while
Thread.sleep(100); // wait 100 msec [Timing]
} // for
System.out.println("read port: " + answer + "\n"); // for debugging
return answer; // give the received string back to the caller
} // read
/** close the connection via the serial line
* @throws Exception
public static void close() throws Exception {
try {
port.close();
System.out.println("close port\n"); // for debugging
} // try
catch (Exception e) {
SMS.showText("Error: close port failed: " + e);
} // catch
} // close
} // Port
Port.java:36: cannot find symbol
symbol : variable SMS
location: class smspack.Port
CommPortIdentifier portId = CommPortIdentifier.getPortIdentifier(SMS.COMPORT);
^
Port.java:45: cannot find symbol
symbol : variable SMS
location: class smspack.Port
SMS.showText("could not open port:" + e);
^
Port.java:67: cannot find symbol
symbol : variable SMS
location: class smspack.Port
SMS.showText("ERROR: send AT command failed; " + "Command: " + atcommand + "; Answer: " + s + " " + e);
^
Port.java:145: cannot find symbol
symbol : variable SMS
location: class smspack.Port
SMS.showText("Error: close port failed: " + e);
^
4 errors

Answer 1

place the java file in a directory named the same as the package (and also do this for the two classes that cannot be found), then compile from above these directories using the full (relative to where you are) path to the files.