Question

Write a Java program that contains a method named ReadAndFindMax. The argument to this method is the filename (of String type). The method opens the file specified in the method argument filename and then reads integers from it. This file can contain any number of integers. Next, the method finds the maximum of these integers and returns it.

The main method must first ask the user to enter the filename; then call ReadAndFindMax method with the entered filename as an argument; and finally it must print the maximum integer value that is returned from this method.

You would have the screenshots similar to shown below (assuming that you are using console I/O):

Enter the file name: myfile.txt

The maximum number is 45

Assuming that the file myfile.txt contains the following four integer numbers:

23

34

45

2

Answer 1

Here is the code for you:

import java.util.*;
import java.io.*;
class ReadFileAndFindMaxInteger
{
    // The argument to this method is the filename (of String type). The method opens the
    // file specified in the method argument filename and then reads integers from it.
    // This file can contain any number of integers.
    // Next, the method finds the maximum of these integers and returns it.
    public static int ReadAndFindMax(String fileName) throws FileNotFoundException
    {
       Scanner sc = new Scanner(new File(fileName));
       int maxValue = sc.nextInt();
       while(sc.hasNext())
       {
          int value = sc.nextInt();
          if(value > maxValue)
              maxValue = value;  
       }
       return maxValue;
    }
   
    // The main method must first ask the user to enter the filename; then call
    // ReadAndFindMax method with the entered filename as an argument; and finally it must
    // print the maximum integer value that is returned from this method.
    public static void main(String[] args) throws FileNotFoundException
    {
       String fileName;
       Scanner sc = new Scanner(System.in);
       System.out.print("Enter the file name: ");
       fileName = sc.next();
       int max = ReadAndFindMax(fileName);
       System.out.println("The maximum number is " + max);
    }
}

And the output screenshot is: