Compare two text files string by string in java

Question

I have two text files and I want to compare the contents of text files using java.

For example First file e1.txt has the content "hello this is india" , and another e2.txt contents "hello this is usa". I want the output should be the text which is not similer in both files(here output should be india or usa).

Problem which I was facing here is that java IO method reads line by line so in this case no output will be given(both lines are different), also white spaces should be ignored. I will be very much thankful if anyone will help me in this problem.

Here is my Code :

 public void fh() throws FileNotFoundException, IOException{
    File f1=new File("C:\\\\Users\\\\Ramveer\\\\Desktop\\\\idrbt Project\\\\e1.txt");
    File f2=new File("C:\\\\Users\\\\Ramveer\\\\Desktop\\\\idrbt Project\\\\e2.txt");
    FileInputStream fi1=new FileInputStream(f1);
    FileInputStream fi2=new FileInputStream(f2); 
    DataInputStream di1=new DataInputStream(fi1);
    BufferedReader br1=new BufferedReader(new InputStreamReader(di1));
    DataInputStream di2=new DataInputStream(fi2);
    BufferedReader br2=new BufferedReader(new InputStreamReader(di2));
    String s1, s2;  
    while ((s1=br1.readLine())!=null && (s2=br2.toString())!=null) 
     {
    if(!s1.equals(s2)){
    System.out.println(s1);
      }
    } 
}

Answer 1

Just as what I commented, use java.util.Scanner

public static void fha(InputStream is1, InputStream is2) throws IOException {
    Scanner sc1 = new Scanner(is1);
    Scanner sc2 = new Scanner(is2);
    while (sc1.hasNext() && sc2.hasNext()) {
        String str1 = sc1.next();
        String str2 = sc2.next();
        if (!str1.equals(str2))
            System.out.println(str1 + " != " + str2);
    }
    while (sc1.hasNext())
        System.out.println(sc1.next() + " != EOF");
    while (sc2.hasNext())
        System.out.println("EOF != " + sc2.next());
    sc1.close();
    sc2.close();
}

Answer 2

Take a look at the StringTokenizer class, and the String.indexOf(String s) method.

You can use a StringTokenizer to break-up a String into sections, separated by delimiters.

You can use String.indexOf(String s) to find a particular String within another String.

You can probably solve your problem using a combination of these.

Answer 3

It depends on how you want the comparison go (e.g. word by word, char by char), i.e. given

 Hello this is India

and

 Hello this is Indonesia

should it output:

1. "India"/"Indonesia"?
2. "ia" vs. "onesia"?

In any case, you can use br1.read() and br2.read() to do a character by character comparison (case 2). Or you could use loops to read each file until the next delimiter (space maybe) and then compare the words.

Answer 4

import java.io.*;

public class CompareTextFiles {

    public static void main(String args[]) throws Exception {

      FileInputStream fstream1 = new FileInputStream("C:\\text1.txt");
      FileInputStream fstream2 = new FileInputStream("C:\\text2.txt");

      DataInputStream in1= new DataInputStream(fstream1);
      DataInputStream in2= new DataInputStream(fstream2);

      BufferedReader br1 = new BufferedReader(new InputStreamReader(in1));
      BufferedReader br2 = new BufferedReader(new InputStreamReader(in2));

      String strLine1, strLine2;


      while((strLine1 = br1.readLine()) != null && (strLine2 = br2.readLine()) != null){
          if(strLine1.equals(strLine2)){
              System.out.println(strLine1);

          }
      }
    }
}