Java

Merging two files

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Join Date: Dec 2008

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Reputation: StarZ is an unknown quantity at this point

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StarZ

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Merging two files

Nov 3rd, 2009

I'm supposed to merge a ordered data of two files into a third file, keeping the data in order. I'm suppose to create a MergeFiles application that merges the integers ordered from low to high in two files into a third file, keeping the order from low to high. Then should merge the two files by taking one element at a time from each, and the third file should contain the numbers from both file from lowest to highest. so, i saved the numbers in wordpad as data1.txt, and data2.txt.

Data1: 11 25 36 45 56 78 90
Data2: 1 3 5 7 54 32 78 99

I can't compile my program because there are still errors and missing codes... can someone help me edit it, and is this how i do it according to the requirements. thx.

so far:

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package mergetwofiles;
 
import java.io.BufferedReader;
import java.io.FileReader;
import java.io.FileWriter;
 
public class Main {
 
 
    public static void main(String[] args) {
        FileReader file1=new FileReader("Data1.txt");
        FileReader file2=new FileReader("Data2.txt");
        BufferedReader br1 = new BufferedReader of(file1);
        BufferedReader br2 = new BufferedReader of(file2);
 
        String temp1, temp2;
        while(br1.readLine() !=null)
        {
        temp1=br1.readLine()+temp1;
        }
        while(br2.readLine()!=null)
        {
        temp2=br2.readLine()+temp2;
        }
        String temp = temp1 + temp2;
        FileWriter fw=new FileWriter("data3.txt");
        char buffer[]=new char[temp.length];
        temp.getChars(0,temp.length(),buffer,0);
        fw.write(buffer);
        file1.close();
        file2.close();
        fw.close();
     }
}
package mergetwofiles;

import java.io.BufferedReader;
import java.io.FileReader;
import java.io.FileWriter;

public class Main {

    
    public static void main(String[] args) {
        FileReader file1=new FileReader("Data1.txt");
        FileReader file2=new FileReader("Data2.txt");
        BufferedReader br1 = new BufferedReader of(file1);
        BufferedReader br2 = new BufferedReader of(file2);
        
        String temp1, temp2;
        while(br1.readLine() !=null)
        {
        temp1=br1.readLine()+temp1;
        }
        while(br2.readLine()!=null)
        {
        temp2=br2.readLine()+temp2;
        }
        String temp = temp1 + temp2;
        FileWriter fw=new FileWriter("data3.txt");
        char buffer[]=new char[temp.length];
        temp.getChars(0,temp.length(),buffer,0);
        fw.write(buffer);
        file1.close();
        file2.close();
        fw.close();
     }
}

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Join Date: Sep 2008

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Reputation: BestJewSinceJC is a splendid one to behold

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BestJewSinceJC BestJewSinceJC is offline

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Nov 3rd, 2009

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Originally Posted by StarZ

I'm supposed to merge a ordered data of two files into a third file, keeping the data in order. I'm suppose to create a MergeFiles application that merges the integers ordered from low to high in two files into a third file, keeping the order from low to high. Then should merge the two files by taking one element at a time from each, and the third file should contain the numbers from both file from lowest to highest. so, i saved the numbers in wordpad as data1.txt, and data2.txt.

Data1: 11 25 36 45 56 78 90
Data2: 1 3 5 7 54 32 78 99

Let me make sure I get what you said: I'm assuming that according to what you said, for the two files above, a third file would be produced:

data3: 1 3 5 7 11 25 32 36 45 56 78 78 90 99

So your only requirement is to order them from lowest to highest and put them in a third file? Or do you also have to read in the numbers in alternating fashion? Either way, since the order in which you read in the elements is trivial, I'll explain how this works.

Options:

1) Ordering your elements from lowest to highest is called sorting. To do so, you will need to use a sorting algorithm. So you could create an array (or ArrayList), read all of the numbers from both files in, and sort the array. In fact, if you do this using an ArrayList, sorting the numbers is as simple as calling the arrayList.sort() method. If you use an array you'll need to write your own sorting method.

2) You could also use a LinkedList to store your values. You would maintain the list's sorted order as you read in the values. To do so, you would figure out what place a particular value belonged in the LinkedList, then you would insert() it in that position. (This might actually be more efficient than option 1, but I'm not positive. Either way, both options work. The reason you'd use a LinkedList in this case is because if you're inserting new values between previous values (example, you currently have 15, 28 in your list and you read in 20) then you'd need to put 20 between 15 and 28 which in an array, would involve copying elements).

After you do one of those two things, you would simply write your list out to a file. To do file writing in Java I usually use PrintWriter . . I'm sure you can find other ways to do it (BufferedWriter, etc) and plenty of examples on google.

Last edited by BestJewSinceJC; Nov 3rd, 2009 at 8:51 pm.

Out.