|Modifier and Type||Method and Description|
Indicates whether some other object is "equal to" this one.
Returns a hash code value for the object.
Returns a string representation of the object.
toStringmethod returns a string that "textually represents" this object. The result should be a concise but informative representation that is easy for a person to read. It is recommended that all subclasses override this method.
toString method for class
returns a string consisting of the name of the class of which the
object is an instance, the at-sign character `
the unsigned hexadecimal representation of the hash code of the
object. In other words, this method returns a string equal to the
getClass().getName() + '@' + Integer.toHexString(hashCode())
equals method implements an equivalence relation
on non-null object references:
trueif and only if
y, multiple invocations of x.equals(y) consistently return
trueor consistently return
false, provided no information used in
equalscomparisons on the objects is modified.
The equals method for class
the most discriminating possible equivalence relation on objects;
that is, for any non-null reference values
y, this method returns
true if and only
y refer to the same object
x == y has the value
Note that it is generally necessary to override the hashCode method whenever this method is overridden, so as to maintain the general contract for the hashCode method, which states that equal objects must have equal hash codes.
public int hashCode()
The general contract of
hashCodemethod on each of the two objects must produce the same integer result.
Object.equals(java.lang.Object)method, then calling the hashCode method on each of the two objects must produce distinct integer results. However, the programmer should be aware that producing distinct integer results for unequal objects may improve the performance of hashtables.
As much as is reasonably practical, the hashCode method defined by class Object does return distinct integers for distinct objects. (This is typically implemented by converting the internal address of the object into an integer, but this implementation technique is not required by the JavaTM programming language.)