Thread: I need to fix this algorithm please. Do you have any suggestion to make this algorithm working fine.thanks

public static void file(String f)throws IOException{
        BufferedReader br3 = new BufferedReader(new FileReader(f));
        int docCount=1;
        int lineSimilar=0;
        int lineNotSimilar=0;
        try {
 
            query = "SELECT Assignment_ID,Assignment_Path FROM assignments";
            ResultSet rs = st.executeQuery(query) ;
 
            int y = 0;
            String x;
 
            String lineA = "";
            String lineB = "";
 
            int similarity = 0;
            int lineSimilar1 = 0;
            int lineSimilar2 = 0;
            String line1 ="";
            String line2 ="";
            line1 ="";
            line2 ="";
            y = 0;
            int doc=0;
 
 
            while ( rs.next() ) {
                BufferedReader br4 = new BufferedReader(new FileReader(rs.getString("assignment_path")));
                br3 = new BufferedReader(new FileReader(f));
                doc = 0;
                y = 0;
                while((line2 = br3.readLine()) != null ){ 
                                        //problem here
                    while((line1 = br4.readLine()) != null){ 
                        if(line2.equals(line1)){           
                            y++;
 
                            //System.out.println(""+line1);
                            doc++;
 
                            lineSimilar++;
                            lineSimilar1++;
                        }else{
                            //System.out.println("line not similar");
                            lineNotSimilar++;
                        }
                    } 
                }
                //System.out.println("line similar"+""+lineSimilar);
 
                if (lineSimilar1 > (doc/2)/2){
                     /*JOptionPane.showMessageDialog(null,"The result against the document number"+" "+docCount+" "+"is plagiarised");
                    JOptionPane.showMessageDialog(null,"The lines similar are:"+"  "+lineSimilar);
                    JOptionPane.showMessageDialog(null,"The lines different are:"+"  "+lineNotSimilar);*/
                    String message="";
                    for(int i=0; i<1; i++){
                        message += "The result against the document number"+" "+docCount+" "+"is plagiarised";
                        message += "\n";
                        message += "The line similar are:"+"  "+lineSimilar;
                        message += "\n";
                        message += "The line different are:"+"  "+lineNotSimilar;
                        message += "\n";
 
                    }
                    JOptionPane.showMessageDialog(null, message);
                    similarity++;
                    //i++;
                }else{
                     String message="";
                    for(int i=0; i<1; i++){
                        message += "The result against the document number"+" "+docCount+" "+"is good";
                        message += "\n";
                        message += "The line similar are:"+"  "+lineSimilar;
                        message += "\n";
                        message += "The line different are:"+"  "+lineNotSimilar;
                        message += "\n";
 
                    }
                }
                docCount++;
                }
        } catch (Exception e) {
            e.printStackTrace();
 
        }

sorry I'm new here!!thanks

You are trying to compare one file with all the assignment files whose locations are stored in database. First thing to me is that there will be memory leak due to not closed buffered reader. Please correct this first. I will look deeper to your algorithm. thanks.

--- Update ---

You'd better split your code into different functional levels. for instance:
public void compareFiles(String file2){
int lineSimilar2 = 0;
try{
origBR = new BufferedReader(new FileReader(file));
int doc = 0;
int y = 0;
String line = "";
String line2 = "";
while((line = origBR.readLine()) != null){
BufferedReader br2 = new BufferedReader(new FileReader(file2));
while((line2 = br2.readLine()) != null){
if(line.equals(line2)){
y++;
doc++;
lineSimilar++;
lineSimilar2++;
}
else
lineNotSimilar++;
}
}

System.out.println(lineSimilar + " lines are similar");
System.out.println(lineNotSimilar + " lines are not similar");
}catch(Exception e){
e.printStackTrace();
}

}

public void compare(){
//read in files from database
//loop each file from resultset and compare with the original file
compareFiles(eachFile);

Alternatively, because you are only reading files and compare them, you may use multiple threads to compare multiple files at the same time