File reading/writing.
Reading an integer from a file data.txt
// Need this import for reading data:
import java.io.*;
// reading data in a Java application
public class FileRead {
public static void main (String [] args) throws IOException {
// Create a buffered reader
// to read from the file data.txt
BufferedReader in = new BufferedReader(
new FileReader("data.txt"));
// string for storing a line of input
String line;
// Read one integer
// prompt the user:
System.out.print("Please enter an integer: ");
// read a line of input:
line = in.readLine();
// check what the input is:
System.out.println("The input is: " + line);
// extract the integer from the entered data:
int n = Integer.parseInt(line);
// print out the value of n:
System.out.println("n = " + n);
// increment n by 1
n = n + 1;
// print out the result:
System.out.println("n = " + n);
// closing a file
in.close();
}
}
Writing into a file:
// Need this import for reading data:
import java.io.*;
// reading data in a Java application
public class FileWrite {
public static void main (String [] args) throws IOException {
// Create a buffered reader
// to read from the file data.txt
BufferedReader in = new BufferedReader(
new FileReader("data.txt"));
// string for storing a line of input
String line;
// open a file for writing
PrintWriter out = new PrintWriter(new BufferedWriter(
new FileWriter("out.txt")));
// read a line of input:
line = in.readLine();
// check what the input is:
out.println("The input is: " + line);
// extract the integer from the entered data:
int n = Integer.parseInt(line);
// print out the value of n:
out.println("n = " + n);
// increment n by 1
n = n + 1;
// print out the result:
out.println("n = " + n);
in.close();
out.close();
}
}
This is an example from CSci 2101 course.