Comparing Stringbuffer Content with Equals

Comparing StringBuffer content with equals

The equals method of StringBuffer is not overridden from Object, so it is just reference equality, i.e., the same as using ==. I suspect the reason for this is that StringBuffer is modifiable, and overriding equals is mostly useful for value-like classes that you might want to use as keys (though lists also have an overridden equals and StringBuffer is kind of a list, so this is a bit inconsistent).

How to compare two StringBuffer Objects using .equals() method?

Try

sb1.toString().equals(sb2.toString());

because StringBuffer#toString method returns the String value of the data stored inside the buffer:

Returns a string representing the data in this sequence. A new String object is allocated and initialized to contain the character sequence currently represented by this object. This String is then returned. Subsequent changes to this sequence do not affect the contents of the String.

How equals() method work in String Buffer?

Just look at the source code*.

You will see that it just calls Object's equals

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

Also consider using StringBuilder see Difference between StringBuilder and StringBuffer

* If using Eclipse ctrl-click on the Object and if the source coded is loaded in your system, it will take you there

I have 2 Same value object of String Buffer Class. String equals() method Showing False result Why?

There is no overriding of equals in the StringBuffer class. So it inherits the definition from Object class. And from Java API we know its behavior:

The equals method for class Object implements the most discriminating
possible equivalence relation on objects; that is, for any non-null
reference values x and y, this method returns true if and only if x
and y refer to the same object (x == y has the value true).

You have two different objects, so equals return false in this case.

String.equals(StringBuilder) and StringBuilder.equals(String) Confusion

No, String.equals does not convert the other argument to a String then compare the characters.

Compares this string to the specified object. 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.

If the other object is not a String, e.g. a StringBuilder, then it will always return false. It will not convert the object to a String.

Like any well-formed equals method, it will test if the given object is the same class (ensuring it's not null first), and if it is, cast it to a String, but it won't call toString or otherwise convert the given object to a String.

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