Plotting in java with gnuplot gives me a line

I am programming in java and i have to make a plot with some values. The values i want to plot are being written in a file called "cleanOutput.txt" and they are separated by ";". I am writing the following commands on a script file that goes into GnuPlot:

try (PrintWriter writer = new PrintWriter(ficheiroComando)) {
                writer.write("set datafile separator \";\"\n");
                writer.write("set size ratio 0.75\n");
                writer.write("set format x \"%.5f\"\n");
                writer.write("set terminal png\n");
                writer.write("set output '" + output + "'\n");
                writer.write("plot [0:30][0:1]'" + input + "' using 1:2 with lines title 'Suscetiveis' lc rgb 'red',\\\n");
                writer.write("'" + input + "' using 1:3 with lines title 'Infetados' lc rgb 'blue',\\\n");
                writer.write("'" + input + "' using 1:4 with lines title 'Recuperados' lc rgb 'green'\n");
            }

I can use any external library as this is a school project. Here you have some lines of the document input to give you some context:

0,000000;0,500000;0,300000;0,200000;
0,200000;0,501467;0,299024;0,199509;
0,300000;0,502929;0,298052;0,199019;
0,400000;0,504385;0,297084;0,198531;
0,500000;0,505835;0,296121;0,198044;
0,600000;0,507280;0,295162;0,197558;
0,700000;0,508718;0,294207;0,197074;
0,800000;0,510152;0,293257;0,196591;

I want to get a plot where the first column is the x and then each of the following columns will be the y, so that i have 3 plots on the same grid. The thing is, i am having trouble with plotting as i am only getting a horizontal line. Anyone can help?

I have tried messing around with changing the columns i am plotting and have tried different scales on the plot.

Solution

As user85421 pointed out in the comments the decimalsign is the problem. Default in gnuplot is typically decimal point .. If you type show decimalsign in the gnuplot console you might get something like this:

decimalsign for input is  . 
decimalsign for output is . 
degree sign for output is °

So, be aware that there is a decimal sign setting for input (input data) and output (numbers in the graph). In gnuplot console type help decimalsign. It's a bit confusing: set decimalsign ',' will not set your input data decimal sign to ,.

If you type:

set decimalsign locale "French"   # or "German" will also work
set decimalsign "."

and after typing show decimalsign, you will get:

decimalsign for input is  , 
decimalsign for output is . 
degree sign for output is °