File Handling in JAVA processing file data


Reading integer from file

This program explains how we can read numerical data from a file and process it.  Remember we need following steps to read from a file:

step-1: create File object and connect the file containing data by passing fileName in object as:

File file = new File(“outputFile.txt”);

Step-2: Test whether the file exists, if it exists 

step-3: Create object to Scanner class and connect it to the file containing data pointed by File object “file” as shown below:

Scanner inputFile = new Scanner(file);

Step-4:  Check if the line being pointed by nextLine() has the data, this is done asL:

while(inputFile.hasNext())

Step-5 read from thefile

sum += inputFile.nextInt();

Now see the complete program, of reading integer values from the file and count the number values in file and find their average.

package com.example;
import javax.print.DocFlavor;
import javax.swing.*;
import java.io.File;
import java.io.IOException;
import java.io.PrintWriter;
import java.util.Scanner;
public class fileHandling
{

public static void main(String[] args) throws IOException
{

int count=0;
int sum =0;
double average;
File file = new File(“outputFile.txt”);
if(file.exists())
{

Scanner inputFile = new Scanner(file);

// checks that the line pointed has the data to be read, if yes then loop proceeds or exits

while(inputFile.hasNext()) 

{

// System.out.println(inputFile.nextLine());// reads the data from the line and moves the pointer to next line
sum += inputFile.nextInt();
count++;

}
inputFile.close();
average= sum/(double)count;
JOptionPane.showMessageDialog(null, “Sum of all values:” + sum + \n+
“The number of values”+ count + \n+
“the average is :”+ average);

}
else
{

JOptionPane.showMessageDialog(null ,“File does not exist”);

}

}

}

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