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Log function call on new line in Java and C#

I have a logging function in CSharp and Java that I use in walking the stack. How do I make each log print to a new line only. Below are my Java and CSharp Functions.
public static void LogFunctionCall(String parameters){
Object trace = Thread.currentThread().getStackTrace()[3];
android.util.Log.i("##################" + trace.toString()+ "", parameters );
}
the java version is this
public static void LogFunctionCall(string parameters,
[System.Runtime.CompilerServices.CallerMemberName] string methodName = "",
[System.Runtime.CompilerServices.CallerFilePath] string sourceFilePath = "",
[System.Runtime.CompilerServices.CallerLineNumber] int sourceLineNumber = 0)
{
var stackFrame = new StackFrame(1);
var callerMethod = stackFrame.GetMethod();
var className = callerMethod.DeclaringType;
System.Diagnostics.Trace.WriteLine("CCCCCCCCCCCCCCCC" + " " + className + " " + methodName + " " + sourceLineNumber + " " + parameters + "\n");
}
I code on a windows machine.
Please where exactly do I need to place the new line character. I tried this
public static void LogFunctionCall(String parameters){
Object trace = Thread.currentThread().getStackTrace()[3];
android.util.Log.i("##################" + trace.toString()+ "", parameters + "\n" );
}
but I still saw some of the logs being clumped up on a single line.

Instead of \n, try \r\n (carriage return and newline). Some text editors will display differently, so the newline may be in there, but whatever app you're using to read the logs might not be displaying it correctly.

You could also try
System.lineSeparator();
I've seen instances where the /n won't work but the lineSep does.

Also, because it hasn't been mentioned, Environment.NewLine will give you the new line character that is configured for the current environment.

Why won't "\t" create a tab?

I want the "Module Code = " and "Result = " to be separated by a tab but whenever I run the code below it literally just outputs
"Module Code = Biology\tResult = 40.0"
public String toString()
{
return "Module Code = " + moduleCode + "\t" + "Result = " + result;
}

The problem is that you're viewing the value of the produced string in the BlueJ window. That window is good for debugging purposes, but it won't exhibit the same behavior that a proper output device would, especially with respect to characters such as newline, tabulation, etc. Those characters will still appear with their escape sequences, just like you typed them in your source code.
In other words, your toString() method is fine and it works as intended. If you want to see its results formatted properly, don't view them using BlueJ -- print them somewhere else. The console is a good choice:
System.out.println(module.toString());

Why won't “\t” create a new line?
well, that is because “\t” is a tabulation not a new line “\n”
if you need a new line try instead
return "Module Code = " + moduleCode + "\n" + "Result = " + result;

Better string manipulation code

I'm looking for an efficient (one line) string manipulation code to achieve this, regex probably.
I have a string, for example, "Calvin" and I need to convert this to "/C/a/l/Calvin".
i.e. take first three characters, separate them using '/' and later append the original string.
This is the code I've come up with and its working fine, just looking for a better one.
String first = StringUtils.substring(prodName, 0, 1);
String second = StringUtils.substring(prodName, 1, 2);
String third = StringUtils.substring(prodName, 2, 3);
String prodPath = path + "/" + first + "/" + second + "/" + third + "/" + prodName + "/" ;

prodName.replaceAll("^(.)(.)(.).*", "/$1/$2/$3/$0")

What is the point of StringUtils.substring(prodName, 0, 1) when the built-in prodName.substring(0, 1) will do the same thing??
Anyway, assuming prodName is always at least 3 characters long (since you didn't give rules for expected output if it is not), this is the fastest way to do it:
String prodPath = path + '/' +
prodName.charAt(0) + '/' +
prodName.charAt(1) + '/' +
prodName.charAt(2) + '/' +
prodName + '/';
Normally, char + char is integer addition, not string concatenation, but since the first value is a String, and the + operator is left-associative, all + operators are string concatenations, not numeric additions.

How about using String.charAt
StringBuilder b = new StringBuilder (path);
b.append ('/').append (prodName.charAt (0))
.append ('/').append(prodName.charAt (1))
.append ('/').append(prodName.charAt (2))
.append ('/').append (prodName).append ('/');

Don't use regex for simple stuff like this. You may save a couple lines, but you loose a lot in readability. Regex usually take some time to understand when reading them.
String s = path;
for (int i = 0; i < 3; i++)
s += prodName.substring(i,i+1) + "/";
s += prodName

You can use MessageFormat.format()
MessageFormat.format("{0}/{1}/{2}/{3}/{4}/", baseDir, name.charAt(0), name.charAt(1), name.charAt(2), name);
imho i would wrap it for readability,
private String getProductionDirectoryPath(String baseDir, String name) {
return MessageFormat.format("{0}/{1}/{2}/{3}/{4}/", baseDir, name.charAt(0), name.charAt(1), name.charAt(2), name);
}

Positive look ahead can be used
public static void main(String[] args) {
String s = "Calvin";
System.out.println(s.replaceAll("(?=^(\\w)(\\w)(\\w))", "/$1/$2/$3/"));
}
O/P:
/C/a/l/Calvin

No use of a regex, but a simple split over nothing =)
String[] firstThree = prodName.split("");
String prodPath = path + "/" + firstThree[0] + "/" + firstThree[1] + "/" + firstThree[2] + "/" + prodName + "/";
Another approach is using charAt():
String prodPath = path + "/" + prodName.charAt(0) + "/" + prodName.charAt(1) + "/"+ prodName.charAt(2) + "/" + prodName + "/";

You said efficient but you maybe meant terse. I doubt either should be an objective, so you have a different problem.
Why do you care that this string transformation requires four lines of code? Are you concerned that something that in your mind is one operation ("create transformed string") is spread over four Java operations? You should extract the four lines of Java into their own method. Then, when you read the code where the operation is needed you have one conceptual operation ("create transformed string") corresponding to one Java operation (call a method). You could call the methid createTransformedString to make the code even clearer.

You can use String Builder:
StringBuilder sb = new StringBuilder();
for (int i = 0; i < 3; i++) {
sb.append("/").append(prodName.charAt(i));
}
sb.append('/').append(prodName);
Or you can put all the code in loop:
int size = 2;
StringBuilder sb = new StringBuilder();
for (int i = 0; i <= size; i++) {
if (i == 0)
sb.append('/');
sb.append(prodName.charAt(i)).append("/");
if (i == size)
sb.append(prodName);
}

How to save information from JTable to a File?

Here is my case:
So far my group and I, managed to read information from an external file and place it in a JTable. But we need an update button. So we guess we should take all the information from JTable after editting something inside it, and replace it with the current information in the same file. So we kind of think we have to overwrite the old file.
So far we got this: (for int i... is a part of the code but can't get it inside the grey area :P)
for(int i = 0; i < model.getRowCount(); i++) {
p += model.getValueAt(i, 0) + " "
+ model.getValueAt(i, 1) + " "
+ (Integer) model.getValueAt(i, 2) + " "
+ model.getValueAt(i, 3) + " "
+ (Integer)model.getValueAt(i, 4) + " "
+ model.getValueAt(i, 5) + " "
+ model.getValueAt(i, 6) + " "
+ model.getValueAt(i, 7) + " "
+ (Integer)model.getValueAt(i, 8) + "\n";
}
// Update File
SaveMember sm = new SaveMember();
sm.update(p);
Inside our SaveMember.java we got:
public void update(String x) throws Exception {
File f = new File("Members/Members.txt");
PrintStream output = new PrintStream(f);
output.print(x);
So by now when we go and change the data and press the button update, it doesn't do anything at all, and doesn't replace the old data with the new.. Thanks for reading! :)

I'm not sure. If you have double checked that your code is executed at all (maybe you forgot to attach the ActionListener to your button - we all do that from time to time...) try flush the output stream and close the stream afterwards.

First check if your code in the for loop is executed at all. Set a breakpoint after the for loop and inspect the string p. If you are not familiar with debugging, print the string to the console with System.out.println(p).
If your code is NOT executed: Check why the method your code is in is not called. Perhaps you forgot to attach an action listener to your update button or the action listener has an early return under some circumstances.
If your code is executed: What do you do with the exception that is thrown by the method update? Make sure to log it with your logger or print it to the console (again via System.out.println(exc)). If you get a FileNotFoundException the path to the file is not correct.

Split a string in Java

I have a function that accepts a message in String form. The message looks like this : "HTTP/1.1 GET /1/ \n"
I have been using the java.String.split method to break down the string into three smaller substrings, version, command, and number. Then I reconstruct the oringal string from the substrings and output it.
However, when I run teh function the program results in ArrayIndex out of bounds : 1, but still functions properly. But when I run the program step by step in the debugger (netbeans) the program does not result in the ArrayIndex out of bounds nonesense and functions as normal
Any suggestions?
Sam
String output = "";
String[] tokens = clientMessage.split(" ");
String version = tokens[0];
String command = tokens[1];
String potNum = tokens[2];
output = version + " " + command + " " + potNum;
EDIT yes, the program is multithreaded, the clientMsessage string contains "HTTP/1.1 GET /1/ \n" all the time, the value fo clientMessage never changes. The clientMessage is a string sent from a client program and then processed on the server and the output is snet back tot eh client but I keep getting the array errors

I suggest you print out/log your inputs. I suspect you are doing something differently when you debug your program. Its possible this works the first time you call it but when its called again, it fails.
Add before the split.
System.out.println("clientMessage >" + clientMessage +"<");
If your output looks like
clientMessage >HTCPCP/1.0 PROPFIND /1/<
clientMessage >HTCPCP/1.0 PROPFIND /1/<
clientMessage ><
It appears you have an empty request message. I imagine this means the client will not be sending more requests and you have to handle this differently.

ArrayIndexOutOfBounds arises when you are accessing index of an array which does not have any values means in your case tokens[1] does not exists. When debugging are you using same string as input??

Sorry this is not an answer but just an additional question to find what is actually wrong and comments are too small to put that much code. The following works for me, so one of your asumptions is wrong:
import java.io.IOException;
public class Main {
public static void main(String[] args) throws IOException {
String clientMessage = "HTTP/1.1 GET /1/ \n";
String[] tokens = clientMessage.split(" ");
String version = tokens[0];
String command = tokens[1];
String potNum = tokens[2];
System.err.println(version + " " + command + " " + potNum);
}
}

It runs OK on my side. I would have to guess that sometimes clientMessage is a value that does not contain enough spaces to be seperated in 3 parts.

Perhaps there is more to the code than you are including here. I put your code in a class as follows and it compiles and runs without error. Is there something missing?
public class Andrew {
public static void main(String args[]) {
String output = "";
String clientMessage = "HTTP/1.1 GET /1/ \n";
String[] tokens = clientMessage.split(" ");
String version = tokens[0];
String command = tokens[1];
String potNum = tokens[2];
output = version + " " + command + " " + potNum;
System.out.println(output);
}
}