org.apache.cayenne.util
Class HashCodeBuilder

java.lang.Object
  extended by org.apache.cayenne.util.HashCodeBuilder

public class HashCodeBuilder
extends Object

Assists in implementing Object.hashCode() methods. The code is based on HashCodeBuilder from commons-lang 2.1.

Since:
3.0

Constructor Summary
HashCodeBuilder()
           Uses two hard coded choices for the constants needed to build a hashCode.
HashCodeBuilder(int initialNonZeroOddNumber, int multiplierNonZeroOddNumber)
           Two randomly chosen, non-zero, odd numbers must be passed in.
 
Method Summary
 HashCodeBuilder append(boolean value)
           Append a hashCode for a boolean.
 HashCodeBuilder append(boolean[] array)
           Append a hashCode for a boolean array.
 HashCodeBuilder append(byte value)
           Append a hashCode for a byte.
 HashCodeBuilder append(byte[] array)
           Append a hashCode for a byte array.
 HashCodeBuilder append(char value)
           Append a hashCode for a char.
 HashCodeBuilder append(char[] array)
           Append a hashCode for a char array.
 HashCodeBuilder append(double value)
           Append a hashCode for a double.
 HashCodeBuilder append(double[] array)
           Append a hashCode for a double array.
 HashCodeBuilder append(float value)
           Append a hashCode for a float.
 HashCodeBuilder append(float[] array)
           Append a hashCode for a float array.
 HashCodeBuilder append(int value)
           Append a hashCode for an int.
 HashCodeBuilder append(int[] array)
           Append a hashCode for an int array.
 HashCodeBuilder append(long value)
           Append a hashCode for a long.
 HashCodeBuilder append(long[] array)
           Append a hashCode for a long array.
 HashCodeBuilder append(Object object)
           Append a hashCode for an Object.
 HashCodeBuilder append(Object[] array)
           Append a hashCode for an Object array.
 HashCodeBuilder append(short value)
           Append a hashCode for a short.
 HashCodeBuilder append(short[] array)
           Append a hashCode for a short array.
 HashCodeBuilder appendSuper(int superHashCode)
           Adds the result of super.hashCode() to this builder.
 int toHashCode()
           Return the computed hashCode.
 
Methods inherited from class java.lang.Object
clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait
 

Constructor Detail

HashCodeBuilder

public HashCodeBuilder()

Uses two hard coded choices for the constants needed to build a hashCode.


HashCodeBuilder

public HashCodeBuilder(int initialNonZeroOddNumber,
                       int multiplierNonZeroOddNumber)

Two randomly chosen, non-zero, odd numbers must be passed in. Ideally these should be different for each class, however this is not vital.

Prime numbers are preferred, especially for the multiplier.

Parameters:
initialNonZeroOddNumber - a non-zero, odd number used as the initial value
multiplierNonZeroOddNumber - a non-zero, odd number used as the multiplier
Throws:
IllegalArgumentException - if the number is zero or even
Method Detail

appendSuper

public HashCodeBuilder appendSuper(int superHashCode)

Adds the result of super.hashCode() to this builder.

Parameters:
superHashCode - the result of calling super.hashCode()
Returns:
this HashCodeBuilder, used to chain calls.
Since:
2.0

append

public HashCodeBuilder append(Object object)

Append a hashCode for an Object.

Parameters:
object - the Object to add to the hashCode
Returns:
this

append

public HashCodeBuilder append(long value)

Append a hashCode for a long.

Parameters:
value - the long to add to the hashCode
Returns:
this

append

public HashCodeBuilder append(int value)

Append a hashCode for an int.

Parameters:
value - the int to add to the hashCode
Returns:
this

append

public HashCodeBuilder append(short value)

Append a hashCode for a short.

Parameters:
value - the short to add to the hashCode
Returns:
this

append

public HashCodeBuilder append(char value)

Append a hashCode for a char.

Parameters:
value - the char to add to the hashCode
Returns:
this

append

public HashCodeBuilder append(byte value)

Append a hashCode for a byte.

Parameters:
value - the byte to add to the hashCode
Returns:
this

append

public HashCodeBuilder append(double value)

Append a hashCode for a double.

Parameters:
value - the double to add to the hashCode
Returns:
this

append

public HashCodeBuilder append(float value)

Append a hashCode for a float.

Parameters:
value - the float to add to the hashCode
Returns:
this

append

public HashCodeBuilder append(boolean value)

Append a hashCode for a boolean.

This adds iConstant * 1 to the hashCode and not a 1231 or 1237 as done in java.lang.Boolean. This is in accordance with the Effective Java design.

Parameters:
value - the boolean to add to the hashCode
Returns:
this

append

public HashCodeBuilder append(Object[] array)

Append a hashCode for an Object array.

Parameters:
array - the array to add to the hashCode
Returns:
this

append

public HashCodeBuilder append(long[] array)

Append a hashCode for a long array.

Parameters:
array - the array to add to the hashCode
Returns:
this

append

public HashCodeBuilder append(int[] array)

Append a hashCode for an int array.

Parameters:
array - the array to add to the hashCode
Returns:
this

append

public HashCodeBuilder append(short[] array)

Append a hashCode for a short array.

Parameters:
array - the array to add to the hashCode
Returns:
this

append

public HashCodeBuilder append(char[] array)

Append a hashCode for a char array.

Parameters:
array - the array to add to the hashCode
Returns:
this

append

public HashCodeBuilder append(byte[] array)

Append a hashCode for a byte array.

Parameters:
array - the array to add to the hashCode
Returns:
this

append

public HashCodeBuilder append(double[] array)

Append a hashCode for a double array.

Parameters:
array - the array to add to the hashCode
Returns:
this

append

public HashCodeBuilder append(float[] array)

Append a hashCode for a float array.

Parameters:
array - the array to add to the hashCode
Returns:
this

append

public HashCodeBuilder append(boolean[] array)

Append a hashCode for a boolean array.

Parameters:
array - the array to add to the hashCode
Returns:
this

toHashCode

public int toHashCode()

Return the computed hashCode.

Returns:
hashCode based on the fields appended


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