Scanner class

[Emanuel Campolo]

Hi everybody.. the following code creates scanner objects that read characters from a string and attempt to match the specified pattern.
Is there any way to read the whole file with the scanner object ? i mean, scan for the next subsequence that matches the pattern ? I want to avoid creating one scanner object per line readed.

 public class Main {
    public static void main(String[] args) {
        try{
            String a;
            Pattern p=Pattern.compile("32\\.\\d\\d\\d\\.\\d\\d\\d");
            File file=new File("archivo.txt");
            FileReader fr=new FileReader(file);
            BufferedReader br=new BufferedReader(fr);
            Scanner s=new Scanner(br);
           
            while((a=br.readLine())!=null){                
                System.out.println(new Scanner(a).findInLine(p));
               
            }    
            
        }catch(Exception e){
            System.out.println("error");
        }
        
    }
}   

[Ankit Garg]

Hi Emanuel! Welcome to javaranch.

Why don't you read the file completely first, then scan it. like this

public class Main {
    public static void main(String[] args) {
        try{
            String a;
            //Pattern p=Pattern.compile("32\\.\\d\\d\\d\\.\\d\\d\\d");
            File file=new File("archivo.txt");
            FileReader fr=new FileReader(file);
            BufferedReader br=new BufferedReader(fr);
            StringBuffer sb = new StringBuffer();
            while((a=br.readLine())!=null){                
                sb.append(a);
               
            }    
            Scanner s=new Scanner(sb.toString());
            while(s.hasNext(p))
            {
                System.out.println(s.findInLine(p));
            }
        }catch(Exception e){
            System.out.println("error");
        }
    }
}

I have not tested this code but I think it will work...

[patrick avery]

If you use scanner.next(), it will read the whole file:

try {
File file = new File("OTHER\\Oats.css");
         Scanner scanner = new Scanner(file);
         while (scanner.hasNext()) {
String xx = scanner.next();
         System.out.println("readFile   - " + xx);
         }
         scanner.close();
       } catch (FileNotFoundException e) {
         e.printStackTrace();
       }
  

[saipavan vallabhaneni]

hi Emanuel,
the following code might help you

  import java.util.*;
import java.util.regex.*;
import java.io.*;
 public class ScannerOnFile {
    public static void main(String[] args) {
        try{
            String a;
            //Pattern p = Pattern.compile(".\\d\\d");
String p = "\\d\\d";
            File file=new File("archivo.txt");
file.createNewFile();
            /*FileReader fr=new FileReader(file);
            BufferedReader br=new BufferedReader(fr);
                    
            while((a=br.readLine())!=null){                
                System.out.println(new Scanner(a).findInLine(p));
               
            }*/ 
 Scanner s=new Scanner(file);
while (s.findInLine(p) != null)
{
System.out.println(s.next());
}
            
        }catch(Exception e){
            System.out.println("error");
        }
        
    }
}     

a scanner can directly take file as an argument...and the scanner's findInLine() can take only a String...so specify the pattern you want in a String and pass it to findInLine() and check the result

[Emanuel Campolo]

Yes ! It works great, thank you.. just a little comment.. I replaced the hasNext(Pattern p) method with the no-arg hasNext() method. That's because, i suppose, if in the first token the pattern is not matched, the expression returns false and it will never get into the loop.

PS:. Sorry for my english, i learned the language reading kathy sierra's certification book

Originally posted by Ankit Garg:
Hi Emanuel! Welcome to javaranch.

Why don't you read the file completely first, then scan it. like this

public class Main {
    public static void main(String[] args) {
        try{
            String a;
            //Pattern p=Pattern.compile("32\\.\\d\\d\\d\\.\\d\\d\\d");
            File file=new File("archivo.txt");
            FileReader fr=new FileReader(file);
            BufferedReader br=new BufferedReader(fr);
            StringBuffer sb = new StringBuffer();
            while((a=br.readLine())!=null){                
                sb.append(a);
               
            }    
            Scanner s=new Scanner(sb.toString());
            while(s.hasNext()) // MODIFIED
            {
                System.out.println(s.findInLine(p));
            }
        }catch(Exception e){
            System.out.println("error");
        }
    }
}

I have not tested this code but I think it will work...

[Emanuel Campolo]

Thank you saipavan vallabhaneni ! but with that code it doesn't even get into the loop.. I tried this and it runs but, while expression returns a false value when it is evaluated the first time.

Scanner s=new Scanner(texto)
while (s.findInLine(p) != null)
{
System.out.println(s.next());
}

Originally posted by saipavan vallabhaneni:
hi Emanuel,
the following code might help you

  import java.util.*;
import java.util.regex.*;
import java.io.*;
 public class ScannerOnFile {
    public static void main(String[] args) {
        try{
            String a;
            //Pattern p = Pattern.compile(".\\d\\d");
String p = "\\d\\d";
            File file=new File("archivo.txt");
file.createNewFile();
            /*FileReader fr=new FileReader(file);
            BufferedReader br=new BufferedReader(fr);
                    
            while((a=br.readLine())!=null){                
                System.out.println(new Scanner(a).findInLine(p));
               
            }*/ 
 Scanner s=new Scanner(file);
while (s.findInLine(p) != null)
{
System.out.println(s.next());
}
            
        }catch(Exception e){
            System.out.println("error");
        }
        
    }
}