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  1. #1
    yasarqamar is offline Member
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    Default Program fails to compare a String Token with a String.

    I'll just post a portion of my code that I have a question about.

    Java Code:
    String strLine = null;
      while ((strLine = br.readLine()) != null)
      {
          String outputLine1 = "";
          String key = "";
          String outputLine2 = "";
          StringTokenizer st = new StringTokenizer(strLine, "<>", true);//System.out.println("yasar");
          while(st.hasMoreTokens()) 
          {
              key = st.nextToken();System.out.println(key);
              //String val = st.nextToken();
              if(key == "<"){
                  outputLine1 += key;
                  outputLine2 += key;
                  String val = st.nextToken();
                  for ( int i = 0; i < val.length(); ++i )
                      {
                      char c = strLine.charAt(i);
                      int j = (int) c;
                      int k = j+1;
                      char d = (char) k;
                      outputLine1 += c;
                      outputLine2 += d;
                      }
              }
              else if(key == ">"){
                  outputLine1 += key;
                  outputLine2 += key;
              }
          }
          output.write(outputLine2);
          //System.out.println(outputLine1);
          System.out.println(outputLine2);
      }
    It fails to compare the token named 'key' in the if-else if condition inside the nested while. As a result, code inside this if-else branch is never executed. Can anybody let me know why is that so? Maybe its something trivial that i'm missing..
    Last edited by yasarqamar; 07-11-2012 at 12:20 PM. Reason: added [code] ... [/code] tags

  2. #2
    JosAH's Avatar
    JosAH is offline Moderator
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    Default Re: Program fails to compare a String Token with a String.

    Don't compare two Strings for equality with the == operator; use the equals( ... ) method instead.

    kind regards,

    Jos
    The only person who got everything done by Friday was Robinson Crusoe.

  3. #3
    yasarqamar is offline Member
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    Default Re: Program fails to compare a String Token with a String.

    Okay i figured out my problem. Strings (which are objects) can not be compared like primitive data types. I thought they can be compared the same way as i was doing in C++.

  4. #4
    yasarqamar is offline Member
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    Default Re: Program fails to compare a String Token with a String.

    Thanks Joe. Ur help is appreciated.

  5. #5
    JosAH's Avatar
    JosAH is offline Moderator
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    Default Re: Program fails to compare a String Token with a String.

    Quote Originally Posted by yasarqamar View Post
    Okay i figured out my problem. Strings (which are objects) can not be compared like primitive data types. I thought they can be compared the same way as i was doing in C++.
    You can only do that in C++ because the == operator is overloaded for the 'string' type objects. Java doesn't have full blown operator overloading (praise the lord for that) ...

    kind regards,

    Jos
    The only person who got everything done by Friday was Robinson Crusoe.

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