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Thread: How to show message which abbrevate week start letter to its full name of the day in java?

  1. #1
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    Default How to show message which abbrevate week start letter to its full name of the day in java?

    Basically i've been trying to create a program which when you enter abbreviations for days it pops up with the full name of the day, e.g M = monday, Tu = tuesday and so forth. Sounds simple enough but i've spent couple of hours constantly making changes to the code and have made a little progress being that there is no compiling error. But the current problem i have now is that the show message dialog box is not appearing after i have entered the letter so i was wondering if any of you guys could see where i've gone wrong:

    import javax.swing.JOptionPane;
    public class DaysOfWeek
    {
      public static void main(String[]args)
      {
    	  String input1 = JOptionPane.showInputDialog("Enter the abbreviation for a day");
    	  String day = (input1);
    	  if (day == "M")
    	  {
    	  JOptionPane.showMessageDialog(null,"Monday");
          }
          else if (day == "Tu")
          {
    	  JOptionPane.showMessageDialog(null,"Tuesday");
          }
      }
    }
    Last edited by Deep_4; November 7th, 2012 at 11:41 AM.


  2. #2
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    Default Re: If statement problem

    Never compare Strings or other objects with ==, use the equals method instead.
    Improving the world one idiot at a time!

  3. #3
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    Default Re: If statement problem

    Yes we must use equals method.
    When a user inputs the abbreviation the String is constructed with the new operator and hence new String object is created. This "==" checks if both the references are pointing to the same object. For example in this case if user inputs the abbreviation as M, then a String M is created using new operator. Now when we compare --> if (day == "M"). Now this second "M" is actually another object which resides in string pool constant. As the objects are different the "if " would result in false and hence would not work. So use "equals" method

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