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Java's String Tokenizer

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Posting Whiz

Java's String Tokenizer

Jul 13th, 2003

Hi. I have just been introduced to string tokenizer in one of the java lessons. It can remove characters from an array of strings. So, I am wondering if it could remove a string from an array of string. For example: "the fish was eaten by the cat". I'd like to remove "the" from this array of string, resulting to: "fish was eaten by cat", without getting all t's, h's and e's from the array of string. Is this possible?

:roll:

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sooim3

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Re: Java's String Tokenizer

Jul 14th, 2003

AFAIK, the StringTokenizer does not in itself remove characters; it breaks up a string in tokens at given delimeters. If StringTokenizer is constructed like this:

StringTokenizer st=new StringTokenizer("the fish was eaten by the cat");

...the default delimeters are:
- space character
- the tab character
- newline character
- carriage-return character
- form-feed character

If you want to remove the 'the' from your string, then the above construction would work, since the sentence consists of space characters that delimits each word.

And one way to remove the 'the' from the string, is using a simple little loop to check if the word, a token, is equals to 'the' or not.

Like such:

Create a new output string
Construct the StringTokenizer with the string that is to be parsed ("the fish was eaten by the cat")

Check each word with a loop:
While there is more tokens
Create a new temporary string with the nextToken()
If the temporary string does not equals 'the'
Add temporary string to the output string
(else do nothing)
print out the outputstring

...That should result in: "fish was eaten by cat"

Hope this is of any help,
/Soo-Im

http://sooim.pp.se/

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samaru

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Re: Java's String Tokenizer

Jul 14th, 2003

The String tokenizer doesn't have a method to remove tokens. If you have a string like "the fish was eaten by the cat" rather than going through the overhead of creating more objects, just use the native method "replace" or "replaceall" that comes with the String object. You can replace the "the" with an empty string and thus take it out.

Check out my blog at http://www.shinylight.com for more stuff about web dev.

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Re: Java's String Tokenizer

Jul 14th, 2003

Thank you so much...So, here I am, trying with those suggestions given...

 Help with Code Tags 
 Java Syntax (Toggle Plain Text) 
class extra{
     public static void main(String[] args){
          String output = "";
          for(int i=0; i<args.length; i++){
                if(args[i] != "the")
                       output+= args[i];
          }
          System.out.println("Results: "+output);
          System.exit(0);
     }
}
class extra{
     public static void main(String[] args){
          String output = "";
          for(int i=0; i<args.length; i++){
                if(args[i] != "the")
                       output+= args[i];
          }
          System.out.println("Results: "+output);
          System.exit(0);
     }
}

I thought the above might work, without using StringTokenizer....but, hmph...it turned out to print the whole thing!

I have tried using sooim3's suggestion, but it didnt work as well, maybe my code is wrong...
I'm not sure...

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sooim3

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Re: Java's String Tokenizer

Jul 14th, 2003

Uhm, my suggestion wasn't at all as good as the one that followed... you could try this:

public class TokenTest {

public static void main(String[] args) {
System.out.println("the fish was eaten by the cat".replaceAll("the", ""));
}
}

/Soo-Im

http://sooim.pp.se/

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Posting Whiz

Re: Java's String Tokenizer

Jul 14th, 2003

Cool~
Thanks...hehe...guess I've learned something new here. Btw, this means that replaceAll is a method in java.lang.String?

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samaru

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Re: Java's String Tokenizer

Jul 14th, 2003

Yes. Check out the Java API docs for String:
http://java.sun.com/j2se/1.4.2/docs/api/java/lang/String.html

The whole J2SE API:
http://java.sun.com/j2se/1.4.2/docs/api/

Check out my blog at http://www.shinylight.com for more stuff about web dev.

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Re: Java's String Tokenizer

Jul 16th, 2003

This code will work if you use

 Help with Code Tags 
 Java Syntax (Toggle Plain Text) 
!args[i].equals("the")
!args[i].equals("the")

instead of

 Help with Code Tags 
 Java Syntax (Toggle Plain Text) 
args[i] != "the"
args[i] != "the"

. The latter doesn't work because you end up comparing the location in memory rather than the contents of the memory, like when you compare pointers in C without dereferencing them. Sometimes it will work, but usually it will not.

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Originally Posted by red_evolve

Help with Code Tags

Java Syntax (Toggle Plain Text)
class extra{
     public static void main(String[] args){
          String output = "";
          for(int i=0; i<args.length; i++){
                if(args[i] != "the")
                       output+= args[i];
          }
          System.out.println("Results: "+output);
          System.exit(0);
     }
}
class extra{ public static void main(String[] args){ String output = ""; for(int i=0; i<args.length; i++){ if(args[i] != "the") output+= args[i]; } System.out.println("Results: "+output); System.exit(0); } }

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Posting Whiz

Re: Java's String Tokenizer

Jul 16th, 2003

wow! thanks so much!

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Re: Java's String Tokenizer

#10

Mar 17th, 2005

Well i wasn't sure where to post my question but since you guys are talking about tokens and all that, i have a question...

this is my first Java course and i am having troubles doing one of the assignments... well i am suppose to read a file containing grades of students...here is an example

034-23-8901 45 78 85 34
342-67-1231 98 45 67 45
452-57-2351 49 78 61 52

the first 9 digits are the social security of the student and the other numbers are the grades. well i am suppose to open this file ( it is named Grades.txt) somehow i am suppose to read the grades and find the average if the student has an average of 90 or above he will be excluded from the final and then my program has to write an outFile named Exemption... it seems very easy but i just can't get it to work...

My question is do i have to use the tokenizer to separate the numbers... if it is possible how can i do it?

Please i will appreciate any help...