"The substring begins at the specified beginIndex and extends to the character at index endIndex - 1. Thus the length of the substring is endIndex-beginIndex."
Indices in Java start at 0.
So  goes from the first character, included, to the 3rd (0, 1, 2), excluded.
To get the last two characters, you have to use the other version: "The substring begins with the character at the specified index and extends to the end of this string." so use (2) (or if you prefer, (2, 4))

Ok that seems prettly clear, but when I plug it in I get an error saying 'string index out of range:4'... not sure what it doesnt like about it.

This is a selection of the data i am importing (4 digits so should work!)

1441      pm          sym      
1551      pm          sym
2332      pm          sym
1818      pm              rep
2002      pm          sym

Hmm, still no, could it be a factor that some of the strings start with a 0? eg 0123..i thought that woulnt matter with strings rather than integers..

my whole code is here( the table class is pasted at the end because i was having trouble making it work another way:

PImage blueImage;
Table dataTable;
int rowCount;

                   

void setup(){
 size (200, 181);
 blueImage = loadImage("blueImage.png");
 dataTable = new Table("testnums.txt");
 rowCount = dataTable.getRowCount();
}
 
 
 
 
void draw() {
 background(255);
 image(blueImage, 0, 0);
 smooth();
 fill(192,0,0);
 noStroke();

for(int row = 1; row < rowCount; row++) {
 String time = dataTable.getString(row, 0); // column 1.
 String daytime = dataTable.getString(row, 1); // column 2.
 String kind = dataTable.getString(row, 2);//column3.
 String hourx = time.substring(2,4);
 
 
 // ellipse(x, y, 9, 9);
 
 
 //textFont("Helvetica.dfont", 32);
 //fill(51);
 //text("time");
 
 println(time);
 println(daytime);
 println(kind);
 println(hourx);
}
}




class Table {
 String[][] data;
 int rowCount;
 
 
 Table() {
   data = new String[10][10];
 }

 
 Table(String filename) {
   String[] rows = loadStrings(filename);
   data = new String[rows.length][];
   
   for (int i = 0; i < rows.length; i++) {
     if (trim(rows[i]).length() == 0) {
       continue; // skip empty rows
     }
     if (rows[i].startsWith("#")) {
       continue;  // skip comment lines
     }
     
     // split the row on the tabs
     String[] pieces = split(rows[i], TAB);
     // copy to the table array
     data[rowCount] = pieces;
     rowCount++;
     
     // this could be done in one fell swoop via:
     //data[rowCount++] = split(rows[i], TAB);
   }
   // resize the 'data' array as necessary
   data = (String[][]) subset(data, 0, rowCount);
 }


 int getRowCount() {
   return rowCount;
 }
 
 
 // find a row by its name, returns -1 if no row found
 int getRowIndex(String name) {
   for (int i = 0; i < rowCount; i++) {
     if (data[i][0].equals(name)) {
       return i;
     }
   }
   println("No row named '" + name + "' was found");
   return -1;
 }
 
 
 String getRowName(int row) {
   return getString(row, 0);
 }


 String getString(int rowIndex, int column) {
   return data[rowIndex][column];
 }

 
 String getString(String rowName, int column) {
   return getString(getRowIndex(rowName), column);
 }

 
 int getInt(String rowName, int column) {
   return parseInt(getString(rowName, column));
 }

 
 int getInt(int rowIndex, int column) {
   return parseInt(getString(rowIndex, column));
 }

 
 float getFloat(String rowName, int column) {
   return parseFloat(getString(rowName, column));
 }

 
 float getFloat(int rowIndex, int column) {
   return parseFloat(getString(rowIndex, column));
 }
 
 
 void setRowName(int row, String what) {
   data[row][0] = what;
 }


 void setString(int rowIndex, int column, String what) {
   data[rowIndex][column] = what;
 }

 
 void setString(String rowName, int column, String what) {
   int rowIndex = getRowIndex(rowName);
   data[rowIndex][column] = what;
 }

 
 void setInt(int rowIndex, int column, int what) {
   data[rowIndex][column] = str(what);
 }

 
 void setInt(String rowName, int column, int what) {
   int rowIndex = getRowIndex(rowName);
   data[rowIndex][column] = str(what);
 }

 
 void setFloat(int rowIndex, int column, float what) {
   data[rowIndex][column] = str(what);
 }


 void setFloat(String rowName, int column, float what) {
   int rowIndex = getRowIndex(rowName);
   data[rowIndex][column] = str(what);
 }
 
 
 // Write this table as a TSV file
 void write(PrintWriter writer) {
   for (int i = 0; i < rowCount; i++) {
     for (int j = 0; j < data[i].length; j++) {
       if (j != 0) {
         writer.print(TAB);
       }
       if (data[i][j] != null) {
         writer.print(data[i][j]);
       }
     }
     writer.println();
   }
   writer.flush();
 }
}

Hmm, your example works for me too, but still nothing for mine. Will have a play around with it. Thanks, L.

Well I got around it by adding a '0' to the start o all of the numerical data in my table, then changing the substrings to go from (3,5) etc, which seems to have sorted it for some reason!(?)

Thanks again for your help.