Question

Create a class called FileSumWrapper with a method that has the signature public static void handle(String filename, int lowerBound).

Make this method call FileSum.read and make your method catch all the errors.

FileSum.read is a method that takes a filename and a lower bound, then sums up all the numbers in that file that are equal to or above the given lower bound.

I'm unsure at how to incorporate the FileSum.read() method to even start anything. I also don't know what the whole "lower bound" means or is suppose to do. Please attach comments/notes as to why something is there/ how it works. I'm also not very great on how to import files. Thank you if you can help even just a bit.

Given:

FileSum.java

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

public class FileSum {

    public static int read(String filename, int lowerBound) throws Exception 
{
        Scanner inputFile = new Scanner(new File(filename));

        int acc = 0;
        boolean atLeastOneFound = false;

        while (inputFile.hasNext()) {
            int data = inputFile.nextInt();
            if (data >= lowerBound) {
                acc += data;
                atLeastOneFound = true;
            }
        }

        if (!atLeastOneFound) {
            throw new UnexpectedException("");
        }
        return acc;
    }
}

---------------------------------------------------------------------------------------------------------

Question1.java

import java.util.Scanner;

public class Question1 {

    public static void main(String[] args) {
        Scanner keyboard = new Scanner(System.in);
        System.out.println("Enter a filename");
        String filename = keyboard.nextLine();
        System.out.println("Enter a lower bound");
        int lowerBound = keyboard.nextInt();

        FileSumWrapper.handle(filename, lowerBound);
    }
}

---------------------------------------------------------------------------------------------------------

err.txt

50 40 30
90
85
23
06
30x
54
675
875
34
2323
423
423
5
5
79
97
90y
7986
5
46
64656
66
6





333 93 9 300 20 2 9 209 290 39 48 85 7847 578048

---------------------------------------------------------------------------------------------------------

t1.txt

50 40 30
90
85
23
06
30
54
675
875
34
2323
423
423
5
5
79
97
90
7986
5
46
64656
66
6





333 93 9 300 20 2 9 209 290 39 48 85 7847 578048

---------------------------------------------------------------------------------------------------------

Input	Output
t1.txtENTER 50	Enter a filename\n Enter a lower bound\n Sum of all numbers in t1.txt is 665177\n

Input	Output
t1.txtENTER 500	Enter a filename\n Enter a lower bound\n Sum of all numbers in t1.txt is 662410\n

Input	Output
t1.txtENTER 5000000	Enter a filename\n Enter a lower bound\n CS112 error: Found no numbers above 5000000\n

Input	Output
t1.txtENTER 6000000	Enter a filename\n Enter a lower bound\n CS112 error: Found no numbers above 6000000\n

Input	Output
t1e.txtENTER 50	Enter a filename\n Enter a lower bound\n CS112 error: Couldn't open t1e.txt\n

Input	Output
t11e.txtENTER 50	Enter a filename\n Enter a lower bound\n CS112 error: Couldn't open t11e.txt\n

Input	Output
err.txtENTER 50	Enter a filename\n Enter a lower bound\n CS112 error: Was reading integers but found something else\n

Answer 1

FileSum.java

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

public class FileSum {
  
public static int read(String filename, int lowerBound) throws Exception
{
Scanner inputFile = new Scanner(new File(filename));

int acc = 0;
boolean atLeastOneFound = false;
  
while (inputFile.hasNext()) {
int data = inputFile.nextInt();
if (data >= lowerBound) {
acc += data;
atLeastOneFound = true;
}
}

if (!atLeastOneFound) {
throw new UnexpectedException("");
}
return acc;
}
}

FileSumWrapper.java

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

public class FileSumWrapper {
  
public static void handle(String fileName, int lowerBound)
{
// section to check:
// 1. If the file exists or not, and
// 2. If only integers are being read from the file or not
Scanner fileReader;
try
{
fileReader = new Scanner(new File(fileName));
while(fileReader.hasNext())
{
if(!isDigit(fileReader.next()))
System.exit(0);
}
fileReader.close();
}catch(FileNotFoundException fnfe){
System.out.println("Error: Couldn't open " + fileName);
System.exit(0);
}
  
// section for calling FileSum.read() method
try
{
int sum = FileSum.read(fileName, lowerBound);
System.out.println("Sum of all numbers in " + fileName + " is " + sum);
  
}catch(Exception ex){
System.out.println("Error: Found no numbers above " + lowerBound);
System.exit(0);
}
}
  
// this method returns true if the String s in an integer, else returns false
private static boolean isDigit(String s)
{
try
{
Integer.parseInt(s);
return true;
}catch(NumberFormatException nfe){
System.out.println("Error: Was reading integers but found something else");
return false;
}
}
}

Question1.java (Main class)

import java.util.Scanner;

public class Question1 {

public static void main(String[] args) {
Scanner keyboard = new Scanner(System.in);

System.out.println("Enter a filename");
String filename = keyboard.nextLine();

System.out.println("Enter a lower bound");
int lowerBound = keyboard.nextInt();

FileSumWrapper.handle(filename, lowerBound);
}
}

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