Object.equals() vs String.equals()

[somin bhuvan]

Hi,

What is the difference between Object.equals() and String.equals(), how this method internally works for both the classes.

- bhuvan

[Jeff Albertson]

In you downloaded the SDK from Sun, it came with a zip file of source code, src.zip.
By all means unzip it and poke though it! In it you'll find that Object's equals
method is defined as:

public boolean equals(Object obj) {
    return (this == obj);
}

And String's equals method is defined as:

public boolean equals(Object anObject) {
    if (this == anObject) {
        return true;
    }
    if (anObject instanceof String) {
        String anotherString = (String)anObject;
        int n = count;
        if (n == anotherString.count) {
            char v1[] = value;
            char v2[] = anotherString.value;
            int i = offset;
            int j = anotherString.offset;
            while (n-- != 0) {
                if (v1[i++] != v2[j++])
                    return false;
            }
            return true;
        }
    }
    return false;
}

As the API states: The result is true if and only if the argument is not null and is a String
object that represents the same sequence of characters as this object.