Question

PrintWriter fout = new PrintWriter(new BufferedWriter(
    new FileWriter("numbers.dat")
)); 
for(int i = start; i <= 100; i = i + 2) { 
    fout.print(i + ", "); 
}

Right now my output is like this:

2, 4, 6, 8, 10,

What I want:

2, 4, 6, 8, 10

Answer 1

Here’s a neat way of doing it:

PrintWriter fout = new PrintWriter(new BufferedWriter(
    new FileWriter("numbers.dat")
)); 

String sep = "";
for(int i = start; i <= 100; i += 2) { 
    fout.print(sep + i);
    sep = ", ";
}

Here’s another way:

PrintWriter fout = new PrintWriter(new BufferedWriter(
    new FileWriter("numbers.dat")
)); 

for(int i = start; i <= 100; i += 2) { 
    fout.print((i == start ? "" : ", ") + i);
}

---

Without being too sure of the function of PrintWriter, it may be more efficient to produce the string with a StringBuffer first:

PrintWriter fout = new PrintWriter(new BufferedWriter(
    new FileWriter("numbers.dat")
));

StringBuffer buffer;

for(int i = start; i <= 100; i += 2) { 
    buffer.append(i == start ? "" : ", ").append(i);
}

fout.print(buffer);

Or more efficiently still:

PrintWriter fout = new PrintWriter(new BufferedWriter(
    new FileWriter("numbers.dat")
));

StringBuffer buffer;

for(int i = start; i <= 100; i += 2) { 
    buffer.append(i).append(", ");
}

buffer.setLength(buffer.length()-1);

fout.print(buffer);