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Thread: Getting error on equals method for objects

  1. #1

    Default Getting error on equals method for objects

    I'm taking an introduction to java class right now, so please don't advice me to something that I have not learned yet. My assignment is that I have to create a class that has two fields. One called length and the other width. I have to make a method that returns the tract area. Similarly, I also have to make a method that indicates whether two objects have the same fields. Here is the code that I have assembled...so far

    // create private fields to hold width and length
    private double width;
    private double length;
     
    //create a constructor that initialized the value
    public LandTract(double wid, double len)
    {
     
    width=wid;
    length=len;
    }
     
    // this method will check to see if two object have same data stored in or
    //not
    public Boolean objectEqualChecker(LandTract object)
    {
    boolean flag;
    if(length.equals(object.length) && width.equals(object.width))
    {
    flag=true;
    }
    }

    My problem is encountered when writing that equals method
    if(length.equals(object.length) && width.equals(object.width))
    , I get an error saying
    HTML Code:
    cannot invoke equals(double) on the primitive type double
    . Meanwhile, I do see, to realize that when I change my fields to capital "Double." The problem disappears; however, in my class I have never dealt with a situation where I have to use capital d in double. In fact, I don't even know what's the difference between Double and double. I do know what double is but not the other one...thanks in advance! for taking your time to read this


  2. #2
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    Default Re: Getting error on equals method for objects

    The equals() method (and all methods) only works with objects from classes. For comparing primitives use the arithmetic operators like == etc.
    See the tutorial: Equality, Relational, and Conditional Operators (The Java™ Tutorials > Learning the Java Language > Language Basics)

    Double is a class. See the API doc for more info: http://docs.oracle.com/javase/7/docs/api/
    If you don't understand my answer, don't ignore it, ask a question.

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