Question

Java console-based question.

Do not use BufferedReader please.

A file named customers.txt contains the names of customers for a local hairdressing salon. Unfortunately, the data in the file is in no particular order yet the owner of the salon would like the data in alphabetical order. Write a Java program that reads the contents of the file into an array of Strings, sorts the array of Strings into alphabetical order, and then writes the content of the array to a file named sortedCustomers.txt.

customers.txt contains one name per line and may contain data similar to:

      Smith, Alexandra
      Downes, Trish
      Akbal, Maria

Note the following:

• You cannot assume how many lines of text are in the file.

• You cannot assume that the file exists.

• When storing the names in the array you may assume an array size of 500 elements.

• When writing the names to the sortedCustomer.txt file there should be one name per line.

  For example:

        Akbal, Maria
        Downes, Trish
        Smith, Alexandra
  

• Your code must use appropriate methods with parameter passing to solve the question.

Answer 1

Code

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

public class Main
{
public static void main(String[] args)
{
String []names=new String[500];
int countNames=0;
try
{          
Scanner scanner = new Scanner(new File("customers.txt"));
while (scanner.hasNextLine())
{
       names[countNames]=scanner.nextLine();
countNames++;
}
scanner.close();
   }
catch (FileNotFoundException e)
{
System.out.println("File not found. Pleae check.");
   }
String temp;
for (int i = 0; i <= countNames - 1; i++)
{
for (int j = 1; j < countNames ; j++)
{ //Apply the bubble Sort
if (CompareString(names[j - 1], names[j]) == 1)
{ //Pass the two adjacent string for comparing
temp = names[j - 1];
names[j - 1] = names[j];
names[j] = temp;
}
}
}

File file = new File("sortedCustomer.txt");
FileWriter fr = null;
try
{
fr = new FileWriter(file);
for(int i=0;i<countNames;i++)
{
fr.write(names[i]+"\r\n");
}
fr.close();
} catch (IOException e)
{
e.printStackTrace();
}
System.out.println("Done!!!");
}
private static int CompareString(String first, String second) {
int len;

if (first.length() >= second.length()) //we need to take the smallest string length
len = second.length();
else
len = first.length();

for (int i = 0; i <= len; i++) {
if (first.charAt(i) > second.charAt(i)) //Suppose the first string letters is greater then return 1;
return 1;
else if (first.charAt(i) < second.charAt(i)) //if second string letter is greater then return -1;
return -1;
}
return 0; //if both the equal then return 0
}
}

output

text files

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