如何读取特定的字符串？

Question

Hi i am trying to make java desktop application where i am receiving value from seril port in my java string variable and i am receiving data through a hardware device and this will throw data continuously i am storing that data in a string variable now i want to get only some specific data from that.

so how can i achieve this i am receiving data in following format

$GPRMC,235949.799,V,,,,,0.00,0.00,050180,,,N*46
$GPVTG,0.00,T,,M,0.00,N,0.00,K,N*32
$GPGGA,235949.799,,,,,0,0,,,M,,M,,*4F
$GPGSA,A,1,,,,,,,,,,,,,,,*1E
$GPGSV,1,1,00*79
$GPGLL,,,,,235949.799,V,N*7D
$GPTXT,01,01,02,ANTSTATUS=OPEN*2B

this string is continuously receiving

i want to get from this string only first line from every String

Here is my code

public class ListPortClass
{
 private int times = 0;



public static void main(String[] s)

{
    BufferedReader br = null;
try
{
     String sCurrentLine;
CommPortIdentifier portIdentifier = CommPortIdentifier.getPortIdentifier("COM6");
if (portIdentifier.isCurrentlyOwned())
{
System.out.println("Port in use!");
}
else {
System.out.println(portIdentifier.getName());

SerialPort serialPort = (SerialPort) portIdentifier.open("ListPortClass", 300);
int b = serialPort.getBaudRate();
System.out.println(Integer.toString(b));
serialPort.setSerialPortParams(300, SerialPort.DATABITS_8, SerialPort.STOPBITS_1, SerialPort.PARITY_NONE);
OutputStream mOutputToPort = serialPort.getOutputStream();
InputStream mInputFromPort = serialPort.getInputStream();
String mValue = "DEBUG_GPS";
System.out.println("beginning to Write . \r\n");
mOutputToPort.write(mValue.getBytes());
System.out.println("DEBUG_GPS Command Written to Port. \r\n");
mOutputToPort.flush();
System.out.println("Waiting for Reply \r\n");
Thread.sleep(500);
byte mBytesIn [];// = new byte[48];
//for(int i=0;i<=mBytesIn.length;i++){
mInputFromPort.read(); 
try{
while(true){
int a = mInputFromPort.read();
char c=(char)a;
//String  c =String.valueOf(a);
//System.out.print(c);
String temp = Character.toString(c);
System.out.print(temp);

}}
catch(IOException e)
{System.out.println(e);}

mOutputToPort.close(); 
mInputFromPort.close();
}
}
catch (Exception ex)
{

System.out.println("Exception : " + ex.getMessage());
}
}
}

here is my updated code

public static void main(String[] s)

{
    BufferedReader br = null;
try
{
     String sCurrentLine;
CommPortIdentifier portIdentifier = CommPortIdentifier.getPortIdentifier("COM6");
if (portIdentifier.isCurrentlyOwned())
{
System.out.println("Port in use!");
}
else {
System.out.println(portIdentifier.getName());

SerialPort serialPort = (SerialPort) portIdentifier.open("ListPortClass", 300);
int b = serialPort.getBaudRate();
System.out.println(Integer.toString(b));
serialPort.setSerialPortParams(300, SerialPort.DATABITS_8, SerialPort.STOPBITS_1, SerialPort.PARITY_NONE);
OutputStream mOutputToPort = serialPort.getOutputStream();
InputStream mInputFromPort = serialPort.getInputStream();
String mValue = "DEBUG_GPS";
System.out.println("beginning to Write . \r\n");
mOutputToPort.write(mValue.getBytes());
System.out.println("DEBUG_GPS Command Written to Port. \r\n");
mOutputToPort.flush();
System.out.println("Waiting for Reply \r\n");
Thread.sleep(500);

try {

            br = new BufferedReader (new InputStreamReader(mInputFromPort));
            while ((sCurrentLine = br.readLine()) != null) {
                System.out.println(sCurrentLine);
            }
}
catch(IOException e){
    e.printStackTrace();
}

//mOutputToPort.close(); 
//mInputFromPort.close();
}
}
catch (Exception ex)
{

System.out.println("Exception : " + ex.getMessage());
}
}
}

i did following code updated code

Answer 1

You already have aBufferedReader object defined in your code, but not used. If you use if you can then use the readLine method. After each sucessful read of a line you can then send it to another method for processing.

Construct your BufferedReader as

br = new BufferedReader(new InputStreamReader(mInputFromPort));

what you want is

//for(int i=0;i<=mBytesIn.length;i++){

// CUT ALL OF THIS CODE

// until here 
try {

        br = new BufferedReader (new InputStreamReader(mInputFromPort));
        while ((sCurrentLine = br.readLine()) != null) {
            System.out.println(sCurrentLine);
        }
} catch(IOException e){
e.printStackTrace();
}

you dont want to be doing mInputFromPort.read(); stuff, you are now going to be using the readLine code NOT both