Reading a .txt file using Scanner class in Java

I am working on a Java program that reads a text file line-by-line, each with a number, takes each number throws it into an array, then tries and use insertion sort to sort the array. I need help with getting the program to read the text file.

I am getting the following error messages:

java.io.FileNotFoundException: 10_Random (The system cannot find the file specified)
at java.io.FileInputStream.open(Native Method)
at java.io.FileInputStream.<init>(Unknown Source)
at java.util.Scanner.<init>(Unknown Source)
at insertionSort.main(insertionSort.java:14)

I have a copy of the .txt file in my "src" "bin" and main project folder but it still cannot find the file. I am using Eclipse by the way.

import java.io.File;
import java.io.FileNotFoundException;
import java.util.Scanner;

public class insertionSort {

public static void main(String[] args) {

    File file = new File("10_Random");

    try {

        Scanner sc = new Scanner(file);

        while (sc.hasNextLine()) {
            int i = sc.nextInt();
            System.out.println(i);
        }
        sc.close();
    } 
    catch (FileNotFoundException e) {
        e.printStackTrace();
    }
 }
}

Solution 1:

You have to put file extension here

File file = new File("10_Random.txt");

Solution 2:

Use following codes to read the file

import java.io.File;
import java.util.Scanner;

public class ReadFile {

    public static void main(String[] args) {

        try {
            System.out.print("Enter the file name with extension : ");

            Scanner input = new Scanner(System.in);

            File file = new File(input.nextLine());

            input = new Scanner(file);


            while (input.hasNextLine()) {
                String line = input.nextLine();
                System.out.println(line);
            }
            input.close();

        } catch (Exception ex) {
            ex.printStackTrace();
        }
    }

}

-> This application is printing the file content line by line

Solution 3:

here are some working and tested methods;

using Scanner

package io;

import java.io.File;
import java.util.Scanner;

public class ReadFromFileUsingScanner {
    public static void main(String[] args) throws Exception {
        File file=new File("C:\\Users\\pankaj\\Desktop\\test.java");
        Scanner sc=new Scanner(file);
        while(sc.hasNextLine()){
            System.out.println(sc.nextLine());
        }
    }
}

Here's another way to read entire file (without loop) using Scanner class

package io;

import java.io.File;
import java.io.FileNotFoundException;
import java.util.Scanner;

public class ReadingEntireFileWithoutLoop {
    public static void main(String[] args) throws FileNotFoundException {
        File file=new File("C:\\Users\\pankaj\\Desktop\\test.java");
        Scanner sc=new Scanner(file);
        sc.useDelimiter("\\Z");
        System.out.println(sc.next());
    }
}

using BufferedReader

 package io;
import java.io.*;
public class ReadFromFile2 {
    public static void main(String[] args)throws Exception {
        File file=new File("C:\\Users\\pankaj\\Desktop\\test.java");
        BufferedReader br=new BufferedReader(new FileReader(file));
        String st;
        while((st=br.readLine())!=null){
            System.out.println(st);
        }
    }
}

using FileReader

package io;
import java.io.*;
public class ReadingFromFile {
    public static void main(String[] args) throws Exception {
        FileReader fr=new FileReader("C:\\Users\\pankaj\\Desktop\\test.java");
        int i;
        while((i=fr.read())!=-1){
            System.out.print((char) i);
        }
    }
}

Solution 4:

1. Make sure the filename is correct (proper capitalisation, matching extension etc - as already suggested).

2. Use the Class.getResource method to locate your file in the classpath - don't rely on the current directory:

   URL url = insertionSort.class.getResource("10_Random");
   
   File file = new File(url.toURI());
   

3. Specify the absolute file path via command-line arguments:

   File file = new File(args[0]);
   

In Eclipse:

1. Choose "Run configurations"
2. Go to the "Arguments" tab
3. Put your "c:/my/file/is/here/10_Random.txt.or.whatever" into the "Program arguments" section

Solution 5:

No one seems to have addressed the fact that your not entering anything into an array at all. You are setting each int that is read to "i" and then outputting it.

for (int i =0 ; sc.HasNextLine();i++)
{
    array[i] = sc.NextInt();
}

Something to this effect will keep setting values of the array to the next integer read.

Than another for loop can display the numbers in the array.

for (int x=0;x< array.length ; x++)
{
    System.out.println("array[x]");
}