Please Simple JAVA I/O exception question

Please follow the bolded instruction of # of lines required etc TY

/**

LineNumberer is the first example program in Chapter 11.

It reads a file and prepends each line with a line number.

For example, if the following is the input file:

Mary had a little lamb

whose fleece was white as snow.

Every where that Mary went,

the lamb was sure to go.

Then the following is the output file (ignoring the // comment symbols)

*/

// /* 1 */ Mary had a little lamb

// /* 2 */ whose fleece was white as snow.

// /* 3 */ Every where that Mary went,

// /* 4 */ the lamb was sure to go.

import java.io.File ;

import java.io.FileNotFoundException ;

import java.io.PrintWriter ;

import java.util.Scanner ;

public class LineNumberer

{

//-----------Start below here. To do: approximate lines of code = 1

// 1. public static void main( ... so that file IO is possible without catching a possible FileNotFoundException

//-----------------End here. Please do not remove this comment. Reminder: no changes outside the todo regions.

{

File infile = null ;

//-----------Start below here. To do: approximate lines of code = 1

// 2. set infile to the file input1

//-----------------End here. Please do not remove this comment. Reminder: no changes outside the todo regions

Scanner scanner = new Scanner(infile) ;

PrintWriter pw = new PrintWriter("output1") ;

int lineNumber = 1 ;

//-----------Start below here. To do: approximate lines .of code = 4

// 3-6. Write the while loop that goes through the input file and prints the output file line by line with the commented line numbers.

//-----------------End here. Please do not remove this comment. Reminder: no changes outside the todo regions.

long length1 = infile.length() ;

pw.close() ;

scanner.close() ;

//This next part is just to show what is in the output file

infile = new File("output1") ;

scanner = new Scanner(infile) ;

while (scanner.hasNextLine()) {

System.out.println(scanner.nextLine()) ;

}

long length2 = infile.length() ;

if (length2 <= length1)

System.out.println("Error: You have to print to the given output file.") ;

}

}