Indicates whether some other object is "equal to" this one.
Computes the value of this execution property.
Returns a hash code value for the object.
The object implements the readExternal method to restore its contents by calling the methods of DataInput for primitive types and readObject for objects, strings and arrays.
Returns a string representation of the object.
The object implements the writeExternal method to save its contents by calling the methods of DataOutput for its primitive values or calling the writeObject method of ObjectOutput for objects, strings, and arrays.
equals method implements an equivalence relation on non-null object references:
- It is reflexive: for any non-null reference value
- It is symmetric: for any non-null reference values
trueif and only if
- It is transitive: for any non-null reference values
- It is consistent: for any non-null reference values
y, multiple invocations of
trueor consistently return
false, provided no information used in
equalscomparisons on the objects is modified.
- For any non-null reference value
equals method for class
Object implements the most discriminating possible equivalence
relation on objects; that is, for any non-null reference values
y, this method returns
true if and only if
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.
trueif this object is the same as the obj argument;
The general contract of
- Whenever it is invoked on the same object more than once during an execution of a Java application, the
hashCodemethod must consistently return the same integer, provided no information used in
equalscomparisons on the object is modified. This integer need not remain consistent from one execution of an application to another execution of the same application.
- If two objects are equal according to the
equals(Object)method, then calling the
hashCodemethod on each of the two objects must produce the same integer result.
- It is not required that if two objects are unequal according to the
Object)method, then calling the
hashCodemethod 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 hash tables.
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 Java™ programming language.)
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
Object returns a string consisting of the name of the class of
which the object is an instance, the at-sign character `
@', and the unsigned hexadecimal representation
of the hash code of the object. In other words, this method returns a string equal to the value of:
getClass().getName() + '@' + Integer.toHexString(hashCode())