Write a method that finds the operations which the results are wrong in given file

Question

Assume that multiple arithmetic operations are stored in a file. However, some of the results are wrong

For example, given operations

1.0 + 2.0 = 4.0

2.5 + 2.5 = 5.0

3.0 / 2.0 = 1.0

the method should return 0th and 2nd line strings.

note:

Consider only those operations: +, -, *, /, %

again:

these operation are stored in a txt file, it needs a read method

Answer 1

import java.util.ArrayList;

import java.io.*;

class MathChecker

{

protected ArrayList<String> A;

public MathChecker()

{

A = new ArrayList<String>();

}

public int GetCount() { return(A.size()); }

public String IndexerGetAtIndex(int iIndexPos)

{

String strReturn = null;

if (iIndexPos>=0 && iIndexPos<A.size())

{

strReturn = (String)A.get(iIndexPos);

}

return(strReturn);

}

public void Go(String filename)

{

try

{

FileReader fileReader = new FileReader(filename);

BufferedReader bufferedReader = new BufferedReader(fileReader);

String inbuff = new String("?");

while (inbuff != null)

{

inbuff = bufferedReader.readLine();

if (inbuff==null || inbuff.length()==0) { break; }

//tokens[0] contains the 1st number; tokens[2] contains the 2nd number

//tokens[1] contains the operations symbol; tokens[3] contains the equal sign

// tokens[4] contains the alleged answer

String tokens[] = (inbuff.trim()).split(" ");

// for (int iLoop=0; iLoop<tokens.length; iLoop++) { System.out.println(" token # " + iLoop + " = " + tokens[iLoop]);}

double num1 = Double.parseDouble(tokens[0]);

double num2 = Double.parseDouble(tokens[2]);

double answer = Double.parseDouble(tokens[4]);

double Answer=0;

switch (tokens[1].charAt(0))

{

case '+' : { Answer = num1 + num2; break; }

case '-' : { Answer = num1 - num2; break; }

case '*' : { Answer = num1 * num2; break; }

case '/' :

{

if (num2==0)

{

Answer = Double.POSITIVE_INFINITY;

}

else

{

Answer = num1/num2;

}

break;

}

case '%' :

{

if (num2==0)

{

Answer = Double.POSITIVE_INFINITY;

}

else

{

Answer = (long)num1%(long)num2;

}

break;

}

} //switch

if (Answer!=answer)

{

A.add(inbuff);

}

} //while

bufferedReader.close();

int n = A.size();

for ( int iLoop=0; iLoop<n; iLoop++)

{

System.out.println((String)A.get(iLoop));

}

}

catch (IOException ex)

{

System.out.println(" IO Exception occurs opening/reading file ");

}

}

public static void main(String args[])

{

if (args.length>=1)

{

MathChecker x = new MathChecker();

x.Go(args[0]);

}

else

{

System.out.println(" issue the following command at the system prompt: \n\n" +

" > java MathChecker filename ");

}

}

}

/******************************************

Input file, E:\mathproblems.dat is:

1.0 + 2.0 = 4.0

2.5 + 2.5 = 5.0

3.0 / 2.0 = 1.0

3.2 * 5.0 = 16.0

15.0 - 7.0 = 8.0

19.0 - 11.0 = 7.0

6.0 * 8.0 = 42.0

7 % 5 = 2

15.0 / 3.0 = 5.0

************************************/