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Thread: this. Keyword

  1. #1
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    Default this. Keyword

    Hi Jnic here
    Please can anybody give me some clarity on the various purposes of the this Keyword?

    public class Employee {
     
      private String name;
      private MyDate birthDate;
      private float  salary;
     
      // Constructor
      public Employee(String name, MyDate DoB, float salary) {
        this.name = name;
        this.birthDate = DoB;
        this.salary = salary;
      }
     
      public String getDetails() {
        return "Name: " + name + "\nSalary: " + salary
               + "\nBirth Date: " + birthDate;
      }
    }


  2. #2
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    Default Re: this. Keyword

    public class Employee {
     
      private String name; //This variable is an instance or class variable
      private MyDate birthDate;
      private float  salary;
     
      // Constructor
      public Employee(String name, MyDate DoB, float salary) {
                           //The variable name above here is a variable local to the constructor
                //this.name refers to the class variable and name refers to the local variable
        this.name = name;
        this.birthDate = DoB;
        this.salary = salary;
      }
     
      public String getDetails() {
        return "Name: " + name + "\nSalary: " + salary
               + "\nBirth Date: " + birthDate;
      }
    }

    this always refers back to the object itself.
    Make two instances of any Object, using the example above:
    Employee A = new Employee(...);
    Employee B = new Employee(...);
    During construction of object A, this.name refers to the instance variable name of object A, and refers to the instance variable name of object B during construction of B.

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    Jnic (May 30th, 2013)

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    Talking Re: this. Keyword

    Thanks jps
    So the this is used to resolve ambiguity between instance Variables of the OBJECT(S) and local variables of the constructor should they be of the same name

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    Default Re: this. Keyword

    They are commonly the same name because they do really represent the same thing. One of those grey areas, it depends on who you ask.
    Some always use different names, some always write out this. for every use, some use this. only when required.

    I lean toward the use of this. and the same variable name because I like the variable name to fully inform the reader what information is held there regardless of whether the data is on the way in, way out, or being stored.
    Much of the old code I read, programmers who went with different names used the better name for the class variable, and left the method variable name of poor quality. Now everyone who calls the method has to decide what that horrible variable name really stands for.
    So I would rather see the same name myself, but again just my opinion

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    aussiemcgr (May 30th, 2013), Jnic (May 31st, 2013)

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    Default Re: this. Keyword

    I prefer to use this. whenever making a reference to a class variable. It is very helpful when you have a block of code with a bunch of different variables and statements to see this. and know, without a doubt, that the variable is a class variable and not a local variable.

    It's the little things in language syntax (both coding and otherwise) that make it easier to interpret.
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    Jnic (May 31st, 2013)

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    Default Re: this. Keyword

    jps
    Thank you for the clarification , So basically it is up to the discretion of the programmer to decide the intention

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