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Writing a unique ID to a text file.

Posted on 2003-10-27
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Last Modified: 2010-04-01
Hi Experts,

I am trying to write to a text file on the server. The twist is I need a unique ID at the start of every input. I am not sure how create a unique ID. Can you help. This what I have so far.

BufferedWriter fp = null;
      String str = new String("blah blah; sdfg; dsfg; dsfg");
         
     try {
         fp = new BufferedWriter(new FileWriter("./webapps/printTest/textTempText.txt", true));
     
         fp.write(str, 0, str.length());
         fp.newLine();
     
         fp.flush();
         fp.close();
   }
     catch (IOException e) {
     }
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Question by:achatburn
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4 Comments
 
LVL 6

Accepted Solution

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kotan earned 1600 total points
ID: 9631463
String str = new java.rmi.server.UID().toString();
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Author Comment

by:achatburn
ID: 9631541
Hi Kotan,

This returns this 18e18a3:f880eeed24:-7fd6. I am a beginning JSP programmer. I would like to know how this works. I will give you a hundred more point if you briefly explain this.
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LVL 6

Expert Comment

by:kotan
ID: 9631572
Get from javadocs,

A UID instance contains three primitive values:
    * unique, an int that uniquely identifies the VM that this UID was generated in, with respect to its host and at the time represented by the time value (an example implementation of the unique value would be a process identifier), or zero for a well-known UID
    * time, a long equal to a time (as returned by System.currentTimeMillis()) at which the VM that this UID was generated in was alive, or zero for a well-known UID
    * count, a short to distinguish UIDs generated in the same VM with the same time value


If you would like to know how does he generate those values, you can check the source.
0
 

Author Comment

by:achatburn
ID: 9631608
You Rock

Thanks
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