Intermediate Java Grep project

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1

I need help on why my code isn’t working.

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here is my code. Is something out of place or not included?

import java.util.regex.Pattern;
import java.util.regex.Matcher;

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

public class Grep {
public Grep() {}

public static void main(String args) {

String fName;

File f;
Scanner s;

for (int fileNumber = 1; fileNumber <= 5; fileNumber++) {
fName = “TestFile” + fileNumber + “.txt”;
try {
f = new File(fName);
s = new Scanner(files[i]);
} catch (FileNotFoundException e) {
System.out.println(“Problem opening file.”);
e.printStackTrace();
return;
}
s.close();
}
Pattern pattern = Pattern.compile(“\w*\d+\w*”);
String line;
Matcher matcher;
while (s.hasNextLine()) {
line = s.nextLine();
matcher = pattern.matcher(line);

if (matcher.find()) {
System.out.println(fName + “:” + line);
}
}
}
}

and here are the errors I get:

Grep.java:22: error: cannot find symbol
s = new Scanner(files[i]);
^ //arrow is under ‘f’ in files
symbol: variable files

location: class Grep
Grep.java:22: error: cannot find symbol
s = new Scanner(files[i]);
^ //arrow is under ‘i’ after files
symbol: variable i
location: class Grep

2 errors

2

Hi there!

Could you make sure to use proper format when posting code to the forums?
image

It makes your code easier to read. :slight_smile:

But are you still having problems with your code?

3

Ah I did not know to use that thank you, and yes I am still having trouble.

import java.util.regex.Pattern;
import java.util.regex.Matcher;

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

public class Grep {
  public Grep {}
  
  public static void main(String[] args) {
    

String fName;
File f;
Scanner s;

for (int fileNumber = 1; fileNumber <= 5; fileNumber++) {
  fName = "TestFile" + fileNumber + ".txt";
  try {
    f = new File(fName);
    s = new Scanner(files[i]);
  } catch (FileNotFoundException e) {
    System.out.println("Problem opening file.");
    e.printStackTrace();
    return;
  }
  s.close();
}
Pattern pattern = Pattern.compile("\\w*\\d+\\w*");
String line;
Matcher matcher;
while (s.hasNextLine()) {
  line = s.nextLine();
  matcher = pattern.matcher(line);
 
  if (matcher.find()) {
    System.out.println(fName + ":" + line);
  }
}
  }
}

I figured out I had an extra ( ) I deleted, this is the last error I get:

rep.java:9: error: expected
public Grep {}
^
1 error

4

Well, if we take a look a your code you have:

public class Grep {
  public Grep {}
}

You’re getting an error on public Grep because it is a constructor that is not declared correctly.

Here is the error code I receive, perhaps it will give you better idea:

Syntax error, insert "Identifier (" to complete MethodHeaderName
5

Ok, I have no idea what to put as the Identifier.

6

I am not sure of its use, but let’s think about this for a moment.

When you create a method, what does its structure look like?

7

I figured out what was wrong, I had pattern and matcher statements out of place and now it works.

import java.util.regex.Pattern;
import java.util.regex.Matcher;

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

public class Grep {
  public Grep () {
    
  }
  
  public static void main(String[] args) {

String fName;
File f;
Scanner s;

for (int fileNumber = 1; fileNumber <= 5; fileNumber++) {
  fName = "TestFile" + fileNumber + ".txt";
  try {
    f = new File(fName);
    s = new Scanner(f);
    String line;
    Pattern pattern = Pattern.compile("\\d+");
Matcher matcher;
while (s.hasNextLine()) {
  line = s.nextLine();
  matcher = pattern.matcher(line);
 
  if (matcher.find()) {
    System.out.println(fName + ":" + line);
  }
}
  } catch (FileNotFoundException e) {
    System.out.println("Problem opening file.");
    e.printStackTrace();
    return;
  }
  s.close();
    }
  }
}
1 Like
8

Excellent! I try not to give too many direct hints, as I find working out a problem to be better in the learning process.

I am glad you got your code working. :slight_smile:

9

Yeah, I get you, but sometimes I need things to be explained to me like I’m 5. :slight_smile:

1 Like
10

I completely understand! That probably would have been my next move had you said you were still having problems. :sweat_smile:

Now just keep chugging along, you’re doing great!