How to parse this string in Java?

Question

prefix/dir1/dir2/dir3/dir4/..

How to parse the dir1, dir2 values out of the above string in Java?

The prefix here can be:

/usr/local/apache2/resumes

Can you make clear what are you trying to parse here?

ismail
– ismail

2009-06-04 12:59:36 +00:00
Commented Jun 4, 2009 at 12:59 — ismail
– ismail, Commented Jun 4, 2009 at 12:59
Sorry,missed them out,just updated.

omg
– omg

2009-06-04 13:00:25 +00:00
Commented Jun 4, 2009 at 13:00 — omg
– omg, Commented Jun 4, 2009 at 13:00
Are you trying to parse a URL?

basszero
– basszero

2009-06-04 13:04:57 +00:00
Commented Jun 4, 2009 at 13:04 — basszero
– basszero, Commented Jun 4, 2009 at 13:04
That prefix totally changes the question.

jjnguy
– jjnguy

2009-06-04 13:09:49 +00:00
Commented Jun 4, 2009 at 13:09 — jjnguy
– jjnguy, Commented Jun 4, 2009 at 13:09

coobird · Accepted Answer · 2009-06-04 13:20:58Z

65

If you want to split the String at the / character, the String.split method will work:

For example:

String s = "prefix/dir1/dir2/dir3/dir4";
String[] tokens = s.split("/");

for (String t : tokens)
  System.out.println(t);

Output

prefix
dir1
dir2
dir3
dir4

Edit

Case with a / in the prefix, and we know what the prefix is:

String s = "slash/prefix/dir1/dir2/dir3/dir4";

String prefix = "slash/prefix/";
String noPrefixStr = s.substring(s.indexOf(prefix) + prefix.length());

String[] tokens = noPrefixStr.split("/");

for (String t : tokens)
  System.out.println(t);

The substring without the prefix "slash/prefix/" is made by the substring method. That String is then run through split.

Output:

dir1
dir2
dir3
dir4

Edit again

If this String is actually dealing with file paths, using the File class is probably more preferable than using string manipulations. Classes like File which already take into account all the intricacies of dealing with file paths is going to be more robust.

edited Jun 4, 2009 at 13:20

answered Jun 4, 2009 at 13:01

coobird

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2 Comments

omg Over a year ago

What if there is / character in prefix?

basszero Over a year ago

Shore, you should edit your question and clarify the possible values of prefix, dir1, etc, etc ... Are you tring to parse a URL?

PermGenError · Accepted Answer · 2012-09-12 21:52:40Z

3

...
String str = "bla!/bla/bla/"

String parts[] = str.split("/");

//To get fist "bla!"
String dir1 = parts[0];

edited Sep 12, 2012 at 21:52

PermGenError

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answered Jun 4, 2009 at 13:04

user101375

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Comments

n3rd · Accepted Answer · 2009-06-04 13:03:46Z

2

In this case, why not use new File("prefix/dir1/dir2/dir3/dir4") and go from there?

answered Jun 4, 2009 at 13:03

n3rd

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Comments

Edward Dale · Accepted Answer · 2009-06-04 13:12:39Z

2

String str = "/usr/local/apache/resumes/dir1/dir2";
String prefix = "/usr/local/apache/resumes/";

if( str.startsWith(prefix) ) {
  str = str.substring(0, prefix.length);
  String parts[] = str.split("/");
  // dir1=parts[0];
  // dir2=parts[1];
} else {
  // It doesn't start with your prefix
}

answered Jun 4, 2009 at 13:12

Edward Dale

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1 Comment

Ken Over a year ago

Almost - you are just parsing the prefix with that substr. Try str = str.substring(prefix.length) instead.

Amit Upadhyay · Accepted Answer · 2016-05-15 18:06:26Z

2

Using String.split method will surely work as told in other answers here.

Also, StringTokenizer class can be used to to parse the String using / as the delimiter.

import java.util.StringTokenizer;
public class Test
{
    public static void main(String []args)
    {
        String s = "prefix/dir1/dir2/dir3/dir4/..";
        StringTokenizer tokenizer = new StringTokenizer(s, "/");
        String dir1 = tokenizer.nextToken();
        String dir2 = tokenizer.nextToken();
        System.out.println("Dir 1  : "+dir1);
        System.out.println("Dir 2 : " + dir2);
    }
}

Gives the output as :

Dir 1  : prefix
Dir 2 : dir1

Here you can find more about StringTokenizer.

answered May 15, 2016 at 18:06

Amit Upadhyay

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4 Comments

Tom Over a year ago

Do you know other outdated classes to solve this task?

Amit Upadhyay Over a year ago

@Tom Is StringTokenizer a outdated class?

Tom Over a year ago

Have you checked the JavaDoc of StringTokenizer lately?

Amit Upadhyay Over a year ago

yes, found this :

StringTokenizer is a legacy class that is retained for compatibility reasons although its use is discouraged in new code. It is recommended that anyone seeking this functionality use the split method of String or the java.util.regex package instead.

thanks

Raghunandan · Accepted Answer · 2012-10-07 18:10:57Z

1

 String result;
 String str = "/usr/local/apache2/resumes/dir1/dir2/dir3/dir4";
 String regex ="(dir)+[\\d]";
 Matcher matcher = Pattern.compile( regex ).matcher( str);
  while (matcher.find( ))
  {
  result = matcher.group();     
  System.out.println(result);                 
}

output-- dir1 dir2 dir3 dir4

answered Oct 7, 2012 at 18:10

Raghunandan

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Comments

Scott Stanchfield · Accepted Answer · 2009-06-04 13:08:13Z

0

If it's a File, you can get the parts by creating an instanceof File and then ask for its segments.

This is good because it'll work regardless of the direction of the slashes; it's platform independent (except for the "drive letters" in windows...)

answered Jun 4, 2009 at 13:08

Scott Stanchfield

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Comments

Ken · Accepted Answer · 2009-06-04 13:13:20Z

0

public class Test {
    public static void main(String args[]) {
    String s = "pre/fix/dir1/dir2/dir3/dir4/..";
    String prefix = "pre/fix";
    String[] tokens = s.substring(prefix.length()).split("/");
    for (int i=0; i<tokens.length; i++) {
        System.out.println(tokens[i]);
    }
    }

}

edited Jun 4, 2009 at 13:13

answered Jun 4, 2009 at 13:03

Ken

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2 Comments

omg Over a year ago

There can have / in prefix too. prefix here is not literally 'prefix'

Ken Over a year ago

Do you know the prefix going into the parse? Then get the length of the prefix and use substring to before calling parse to just get the last segment of the string.

thecarlhall · Accepted Answer · 2009-06-04 13:41:46Z

0

String.split(String regex) is convenient but if you don't need the regular expression handling then go with the substring(..) example, java.util.StringTokenizer or use Apache commons lang 1. The performance difference when not using regular expressions can be a gain of 1 to 2 orders of magnitude in speed.

answered Jun 4, 2009 at 13:41

thecarlhall

Comments

basszero · Accepted Answer · 2009-06-04 13:01:56Z

-1

String s = "prefix/dir1/dir2/dir3/dir4"

String parts[] = s.split("/");

System.out.println(s[0]); // "prefix"
System.out.println(s[1]); // "dir1"
...

answered Jun 4, 2009 at 13:01

basszero

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1 Comment

omg Over a year ago

There can have / in prefix too.

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