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Java string comparison failing

Posted on 2014-01-06
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Last Modified: 2014-01-06
I have a java method that passes in a string and is comparing the value in the string to a direction (i.e "East", "West", "North", "South").  When it finds a match it returns an Directions object (i.e Directions.East, Directions.West, Directions.North, Directions.South).  I am making the call to the method as follows: convertDirection(eElement.getAttribute("startDirection"));

Here is the method:
   private static Directions.Direction convertDirection(String dir)
   {
      System.out.printf("Direction in method: %s Length=%d\n", dir, dir.length());
      if(dir=="East")
      {
         return Directions.East;
      }
      if(dir=="West")
      {
         return Directions.West;
      }
      if(dir=="North")
      {
         return Directions.North;
      }
      if(dir=="South")
      {
         return Directions.South;
      }
      return Directions.North;
   } 

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If the XML attribute contains "West", when I debug the method, dir shows "West" and the string length of dir is 4 so I don't have any extra unseen characters.  However, the if(dir=="West") statement returns false so it doesn't return my West direction and falls through to the end of the method and returns North.  If I hard code the call as follows:
convertDirection("West");

The method works correctly.  I've tried creating a string variable and assigning the results of eElement.getAttribute("startDirection") to the variable and passing that into the method but it still doesn't work.

Any help is greatly appreciated as I have to have this working by tomorrow morning and I am at a complete loss.
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Question by:dyarosh
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Accepted Solution

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CPColin earned 500 total points
ID: 39760944
Try using dir.equals("West") instead of the == operator. The equals() method will compare the strings' contents. The == operator is checking to see if the two strings are the exact same object, which will usually fail.
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Expert Comment

by:CPColin
ID: 39760948
Also, if Directions is an enum, you could use Directions.valueOf(dir) and it'll do the same thing in one line as the whole method you wrote. Be careful, though, because that method is case-sensitive and throws an IllegalArgumentException if the value doesn't exist.
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Author Closing Comment

by:dyarosh
ID: 39761168
Thank you.  That did the trick.
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