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com.tangosol.util.comparator
Class EntryComparator

java.lang.Object
com.tangosol.util.Base
com.tangosol.util.comparator.SafeComparator
com.tangosol.util.comparator.EntryComparator

All Implemented Interfaces:

ExternalizableLite, PortableObject, EntryAwareComparator, QueryMapComparator, Serializable, Comparator

public class EntryComparator

extends SafeComparator

Comparator implementation used to compare map entries. Depending on the comparison style this comparator will compare entries' values, entries' keys or, when the provided comparator is an instance of QueryMapComparator, the entries themselves.

Author:

gg 2002.12.14

Field Summary

static int	CMP_AUTO Indicates that this EntryComparator should choose the comparison style based on the underying comparator type.
static int	CMP_ENTRY Indicates that entries that implement QueryMap.Entry interface will be compared using the compareEntries() method.
static int	CMP_KEY Indicates that this EntryComparator should compare the entries' keys.
static int	CMP_VALUE Indicates that this EntryComparator should compare the entries' values.
protected int	m_nStyle Comparison style utilized by this EntryComparator.

Fields inherited from class com.tangosol.util.comparator.SafeComparator

INSTANCE, m_comparator

Constructor Summary

EntryComparator()
Default constructor (for ExternalizableLite and PortableObject).

EntryComparator(Comparator comparator)
Construct an EntryComparator to compare entries' values using the provided Comparator object.

EntryComparator(Comparator comparator, int nStyle)
Construct an EntryComparator to compare entries using the provided Comparator object according to the specified comparison style.

Method Summary

int	compare(Object o1, Object o2) Compares two arguments for order.
boolean	equals(Object o) Determine if two EntryComparator objects are equal.
int	getComparisonStyle() Obtain the comparison style value utilized by this EntryComparator.
boolean	isCompareEntry() Check whether or not this EntryComparator pass entries themselves for comparison to the underlying compareEntries() method.
boolean	isCompareKey() Check whether or not this EntryComparator uses entries' keys to pass for comparison to the underlying Comparator.
boolean	isCompareValue() Check whether or not this EntryComparator uses entries' values to pass for comparison to the underlying Comparator.
void	readExternal(DataInput in) Restore the contents of this object by loading the object's state from the passed DataInput object.
void	readExternal(PofReader in) Restore the contents of a user type instance by reading its state using the specified PofReader object.
void	writeExternal(DataOutput out) Save the contents of this object by storing the object's state into the passed DataOutput object.
void	writeExternal(PofWriter out) Save the contents of a POF user type instance by writing its state using the specified PofWriter object.

Methods inherited from class com.tangosol.util.comparator.SafeComparator

compareEntries, compareSafe, getComparator, hashCode, isKeyComparator, isKeyComparator, toString

Field Detail

CMP_AUTO

public static final int CMP_AUTO

Indicates that this EntryComparator should choose the comparison style based on the underying comparator type.

See Also:

Constant Field Values

CMP_VALUE

public static final int CMP_VALUE

Indicates that this EntryComparator should compare the entries' values.

See Also:

Constant Field Values

CMP_KEY

public static final int CMP_KEY

Indicates that this EntryComparator should compare the entries' keys.

See Also:

Constant Field Values

CMP_ENTRY

public static final int CMP_ENTRY

Indicates that entries that implement QueryMap.Entry interface will be compared using the compareEntries() method.

See Also:

Constant Field Values

m_nStyle

protected int m_nStyle

Comparison style utilized by this EntryComparator. Valid values are any of the CMP_* constants.

Constructor Detail

EntryComparator

public EntryComparator()

Default constructor (for ExternalizableLite and PortableObject).

EntryComparator

public EntryComparator(Comparator comparator)

Construct an EntryComparator to compare entries' values using the provided Comparator object. The EntryComparator will choose the comparison style based on the specified comparator type: if the comparator is an instance of the KeyExtractor, the CMP_KEY style will be assumed; otherwise, the CMP_VALUE style is used.

Parameters:

comparator - the comparator to use; if not specified the "natural" comparison of entries' values is used

EntryComparator

public EntryComparator(Comparator comparator,
                       int nStyle)

Construct an EntryComparator to compare entries using the provided Comparator object according to the specified comparison style. If the style is CMP_AUTO then the comparator type is checked: if the comparator is an instance of the KeyExtractor, the CMP_KEY style will be assumed; otherwise, the CMP_VALUE style is used.

Parameters:

comparator - the comparator to use; if not specified the "natural" comparison is used

nStyle - the comparison style to use; valid values are any of the CMP_* constants

Method Detail

compare

public int compare(Object o1,
                   Object o2)

Compares two arguments for order. The arguments must be Map.Entry objects. Depending on the comparison style, this method will pass either the entries' values, keys or the entries themselves to the underlying Comparator.

Specified by:

compare in interface Comparator

Overrides:

compare in class SafeComparator

Parameters:

o1 - the first object to be compared

o2 - the second object to be compared

Returns:

a negative integer, zero, or a positive integer as the first argument is less than, equal to, or greater than the second

equals

public boolean equals(Object o)

Determine if two EntryComparator objects are equal.

Specified by:

equals in interface Comparator

Overrides:

equals in class SafeComparator

Parameters:

o - the other object

Returns:

true if the passed object is equal to this

See Also:

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

getComparisonStyle

public int getComparisonStyle()

Obtain the comparison style value utilized by this EntryComparator. The returned value should be one of the CMP_* constants.

Returns:

the comparison style value

isCompareValue

public boolean isCompareValue()

Check whether or not this EntryComparator uses entries' values to pass for comparison to the underlying Comparator.

Returns:

true iff entries' values are used for comparison

isCompareKey

public boolean isCompareKey()

Check whether or not this EntryComparator uses entries' keys to pass for comparison to the underlying Comparator.

Returns:

true iff entries' keys are used for comparison

isCompareEntry

public boolean isCompareEntry()

Check whether or not this EntryComparator pass entries themselves for comparison to the underlying compareEntries() method.

Returns:

true iff entries themselves are used for comparison

readExternal

public void readExternal(DataInput in)
                  throws IOException

Restore the contents of this object by loading the object's state from the passed DataInput object.

Specified by:

readExternal in interface ExternalizableLite

Overrides:

readExternal in class SafeComparator

Parameters:

in - the DataInput stream to read data from in order to restore the state of this object

Throws:

IOException - if an I/O exception occurs

NotActiveException - if the object is not in its initial state, and therefore cannot be deserialized into

writeExternal

public void writeExternal(DataOutput out)
                   throws IOException

Save the contents of this object by storing the object's state into the passed DataOutput object.

Specified by:

writeExternal in interface ExternalizableLite

Overrides:

writeExternal in class SafeComparator

Parameters:

out - the DataOutput stream to write the state of this object to

Throws:

IOException - if an I/O exception occurs

readExternal

public void readExternal(PofReader in)
                  throws IOException

Restore the contents of a user type instance by reading its state using the specified PofReader object.

Specified by:

readExternal in interface PortableObject

Overrides:

readExternal in class SafeComparator

Parameters:

in - the PofReader from which to read the object's state

Throws:

IOException - if an I/O error occurs

writeExternal

public void writeExternal(PofWriter out)
                   throws IOException

Save the contents of a POF user type instance by writing its state using the specified PofWriter object.

Specified by:

writeExternal in interface PortableObject

Overrides:

writeExternal in class SafeComparator

Parameters:

out - the PofWriter to which to write the object's state

Throws:

IOException - if an I/O error occurs

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