JAVA EE: Java Tutorial : Java Object Class(equals method-book)

Wednesday, 3 February 2016

Java Tutorial : Java Object Class(equals method-book)

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Java Tutorial : Java Object Class(equals method-book)

Book.java

public class Book
{
    private String name;
    private String isbnNumber;

    public Book(String name, String isbnNumber)
    {
        super();
        this.name = name;
        this.isbnNumber = isbnNumber;
    }

    public String getName()
    {
        return name;
    }

    public void setName(String name)
    {
        this.name = name;
    }

    public String getIsbnNumber()
    {
        return isbnNumber;
    }

    public void setIsbnNumber(String isbnNumber)
    {
        this.isbnNumber = isbnNumber;
    }

}

ObjectClassTest.java

public class ObjectClassTest
{

    public static void main(String[] args)
    {
        Book childrenStoryBookObj = new Book("Children Story", "2000");
        Book KidStoryBookObj = new Book("Kids Story", "2000");

        System.out.println("childrenStoryBookObj.hashCode() = "
                + childrenStoryBookObj.hashCode());
        
        System.out.println("KidStoryBookObj.hashCode()      = "
                + KidStoryBookObj.hashCode());

        /*
         * The equals() method provided in the Object class
         * uses the identity operator (==) to determine
         * whether two objects are equal.
         * 
         * For objects, The equals() method provided by
         * Object tests whether the object references are
         * equal—that is, if the objects compared are the
         * exact same object.
         */

        System.out
                .println("childrenStoryBookObj.equals(KidStoryBookObj)      = "
                        + childrenStoryBookObj
                                .equals(KidStoryBookObj));

        System.out
                .println("childrenStoryBookObj.equals(childrenStoryBookObj) = "
                        + childrenStoryBookObj
                                .equals(childrenStoryBookObj));

        Integer a = 10;
        Integer b = 10;

        /*
         * For primitive data types,it won't check the
         * Object reference.
         */
        System.out.println("a.equals(b) = " + a.equals(b));

    }

}

Output

childrenStoryBookObj.hashCode() = 1704856573
KidStoryBookObj.hashCode()      = 705927765
childrenStoryBookObj.equals(KidStoryBookObj)      = false
childrenStoryBookObj.equals(childrenStoryBookObj) = true
a.equals(b) = true