org.moeaframework.core.variable
Class BinaryVariable

java.lang.Object
  org.moeaframework.core.variable.BinaryVariable

All Implemented Interfaces:

Serializable, Variable

public class BinaryVariable
extends Object
implements Variable

Decision variable for binary strings.

See Also:

Serialized Form

Constructor Summary

BinaryVariable(int numberOfBits)
Constructs a binary variable with the specified number of bits.

Method Summary

int	cardinality() Returns the number of bits in this variable set to true.
void	clear() Sets all bits in this variable to false.
BinaryVariable	copy() Returns an independent copy of this decision variable.
boolean	equals(Object obj) Indicates whether some other object is "equal to" this one.
boolean	get(int index) Returns the value of the bit at the specified index.
BitSet	getBitSet() Returns a BitSet representing the state of this variable.
int	getNumberOfBits() Returns the number of bits stored in this variable.
int	hammingDistance(BinaryVariable variable) Returns the Hamming distance between this instance and the specified BinaryVariable.
int	hashCode() Returns a hash code value for the object.
boolean	isEmpty() Returns true if all bits in this variable are set to false; false otherwise.
void	set(int index, boolean value) Sets the value of the bit at the specified index.
String	toString() Returns a string representation of the object.

Methods inherited from class java.lang.Object

clone, finalize, getClass, notify, notifyAll, wait, wait, wait

Constructor Detail

BinaryVariable

public BinaryVariable(int numberOfBits)

Constructs a binary variable with the specified number of bits. All bits are initially set to false.

Parameters:

numberOfBits - the number of bits stored in this variable

Method Detail

getNumberOfBits

public int getNumberOfBits()

Returns the number of bits stored in this variable.

Returns:

the number of bits stored in this variable

cardinality

public int cardinality()

Returns the number of bits in this variable set to true.

Returns:

the number of bits in this variable set to true

clear

public void clear()

Sets all bits in this variable to false.

isEmpty

public boolean isEmpty()

Returns true if all bits in this variable are set to false; false otherwise.

Returns:

true if all bits in this variable are set to false; false otherwise

get

public boolean get(int index)

Returns the value of the bit at the specified index.

Parameters:

index - the index of the bit to return

Returns:

the value of the bit at the specified index

Throws:

IndexOutOfBoundsException - if the index is out of bounds (index < 0) || (index >= getNumberOfBits())

set

public void set(int index,
                boolean value)

Sets the value of the bit at the specified index.

Parameters:

index - the index of the bit to set

value - the new value of the bit being set

Throws:

IndexOutOfBoundsException - if the index is out of bounds (index < 0) || (index >= getNumberOfBits())

getBitSet

public BitSet getBitSet()

Returns a BitSet representing the state of this variable.

Returns:

a BitSet representing the state of this variable

hammingDistance

public int hammingDistance(BinaryVariable variable)

Returns the Hamming distance between this instance and the specified BinaryVariable. The Hamming distance is the number of bit positions in which the two binary strings differ.

Parameters:

variable - the other BinaryVariable

Returns:

the Hamming distance between this instance and the specified BinaryVariable

Throws:

IllegalArgumentException - if the two binary strings differ in the number of bits

copy

public BinaryVariable copy()

Description copied from interface: Variable

Returns an independent copy of this decision variable. It is required that x.copy() is completely independent from x. This means any method invoked on x.copy() in no way alters the state of x and vice versa. It is typically the case that x.copy().getClass() == x.getClass() and x.copy().equals(x).

Specified by:

copy in interface Variable

Returns:

an independent copy of this decision variable

hashCode

public int hashCode()

Description copied from class: java.lang.Object

Returns a hash code value for the object. This method is supported for the benefit of hashtables such as those provided by java.util.Hashtable.

The general contract of hashCode is:

• Whenever it is invoked on the same object more than once during an execution of a Java application, the hashCode method must consistently return the same integer, provided no information used in equals comparisons 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 hashCode method 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.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 Java^TM programming language.)

Overrides:

hashCode in class Object

Returns:

a hash code value for this object.

See Also:

Object.equals(java.lang.Object), Hashtable

equals

public boolean equals(Object obj)

Description copied from class: java.lang.Object

Indicates whether some other object is "equal to" this one.

The equals method implements an equivalence relation on non-null object references:

• It is reflexive: for any non-null reference value x, x.equals(x) should return true.
• It is symmetric: for any non-null reference values x and y, x.equals(y) should return true if and only if y.equals(x) returns true.
• It is transitive: for any non-null reference values x, y, and z, if x.equals(y) returns true and y.equals(z) returns true, then x.equals(z) should return true.
• It is consistent: for any non-null reference values x and y, multiple invocations of x.equals(y) consistently return true or consistently return false, provided no information used in equals comparisons on the objects is modified.
• For any non-null reference value x, x.equals(null) should return false.

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).

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.

Overrides:

equals in class Object

Parameters:

obj - the reference object with which to compare.

Returns:

true if this object is the same as the obj argument; false otherwise.

See Also:

Object.hashCode(), Hashtable

toString

public String toString()

Description copied from class: java.lang.Object

Returns a string representation of the object. In general, the toString method 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.

The 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())
 

Overrides:

toString in class Object

Returns:

a string representation of the object.