Thread: Read and write to a text file and calculate values

Hi, thanks for your reply, I have no problem with reading and writing the file, i am struggling with calculating the time taken for each journey and compare it with user input. : )

I don't know what to use to set a specific value in the text file, for instant how do I assign the third line of the text file into a variable.
Thanks I think to compare the result an if statement does the work. : )

Originally Posted by Norm

Can you post the code for the reading the first two lines?
Explain what the problem is with reading the third line.

it reads the text file line by line:

File infile = new File("data.txt");
try {

Scanner scanner = new Scanner(infile);

while (scanner.hasNextLine()) {
String line = scanner.nextLine();
System.out.println(line);
}
scanner.close();
} catch (FileNotFoundException e) {
e.printStackTrace();
}


Are you asking how to write data to a text file?

I am trying to calculate the time for each journey but to do that i need to call the values in the text file. I dont actually know how to add my calculation to the above code.

is it possible to use a for loop to read through the text file and calculate the time. Or a for loop within a for loop !

Originally Posted by Norm

Does that code compile and execute and print out the correct values?

It does print the first three line of the txt file and displays the result.

Originally Posted by Norm

The next thing you need to do is use the value read into the number of changes to read in that number of lines worth of data (distance and speed).

Could you expand a little bit more on this please!

posts deleted by s.sariyan:

post 1:

i wrote the text file values at the top; first, second and third journey and parts of the formula is at the top too:
text file contains:
first
1
100 40
200 70
second
0
300 60
third
2
300 80
200 50
400 60


and format plus formulas:

<name>
<N> // N is the number of changes
<FB><DB> // for each leg B, FB is the distance and DB is the speed. Note B=(N+1)

post 2:
the data to work with are the distance, the speed and number of changes in journey, the formulas are
the distance devided by speed in which :

program needs to read data in textfile from the following format:

<name> // First, Second, Third
<N> // N is the number of changes
<FB><DB> // for each leg B, FB is the distance and DB is the speed. Note B=(N+1).

--- Update ---

sorry for my english language : (

post 3:
the text file contains:

first //Name
1 //Number of changes
100 40 //distans and 40 the speed
200 70 //distans and 70 the speed

second //Second journey
0 //number of change
300 60 // 300 distance and 60 speed

third //third journey
2 // number of change
300 80 // the distance and the speed
200 50 // the distance and the speed
400 60 // the distance and the speed

i dont know how to read the data from the text file in the following format:
<name>
<number of changes>
<distance> and <speed>

in terms of calculations, the program should calculate the time that takes for each journey then the program should compare the time with requested time from the user. if the calculated time matches the user input then the program should display the output.

post 4:
I have no problem with reading and writing the file line by line,, I am struggling with reading the file in this specific format. I dont know how to assign data in the text file to variables for later calculations.

The formula is: time = distance(number of change+1) devided by speed(number of changes +1) i am also not sure about the formula. how to compare the result of calculation with user input!

the steps:
1.Request time period from the user
2.read the text file in following format(mentioned above)
3.calculate the time that takes for each journey in the text file
4.compare the result with user input
5.display the output based on the comparison(if the journeys are appropriate or not)
6.if the journey is appropriate and matches the user input, save it to a different text file

I hope i was able to explain it and make it more understandable : ) Thank you

post 5:
user= JOptionPane.showInputDialog ( "Request Time:" );
Scanner inFile = new Scanner(new FileReader ("data.txt"));
String user;
String name;
int change;
int distance;
int speed;
int sum;
int ch = Integer.parseInt(args[0]);
int di = Integer.parseInt(args[1]);
int sp = Integer.parseInt(args[2]);

JOptionPane.showMessageDialog(null, "journey name: "+name+" \n Number of Changes: "+ch+" \n Distance and speed: "+di, "Journey Planner",JOptionPane.INFORMATION_MESSAGE);

}

}

i think that I have done this completely wrong, as i mentioned i am a complete beginner sorry : )