de.frame4j.util

Class PropMapHelper.Entry

java.lang.Object

de.frame4j.util.PropMapHelper.Entry

All Implemented Interfaces:

Serializable, Cloneable, Comparable<Object>, Map.Entry<CharSequence,String>

Enclosing class:

PropMapHelper

public static final class PropMapHelper.Entry
extends Object
implements Map.Entry<CharSequence,String>, Comparable<Object>, Serializable, Cloneable

An entry: key value pair for (Prop)Maps.

An object of this class represents one map entry of type Map.Entry<CharSequence, String>.

According to the properties rules documented and implemented by the class PropMap (using this class) the key is a non empty String that neither begins or ends with white space.

The key of an Entry object is always final.

For the value any String including null and empty is allowed. The value may be changed any time, if immutable is false. immutable itself is set finally an construction.

Hint: Allowing the value null is (slightly) contradictory to Map's rules inherited by the using classes PropMap, AppLangMap and Prop but is very useful enhancement especially for Prop allowing to distinguish an empty and no or not yet set value. (The rationale behind non null value for Map is not quite clear — but the disadvantages in some applications are.)

Implementation hint: All keys and also all values shorter than 19 are made unique (by String.intern()).


© Copyright 2004 Albrecht Weinert.

Version:

like the enclosing class PropMapHelper

Author:

Albrecht Weinert

See Also:

Map, Map.Entry, Serialized Form

Field Summary

Fields

Modifier and Type	Field and Description
protected int	entHash The hash code of this entry.
protected boolean	immutable The value of this entry is immutable.
protected String	key The key of this entry.
protected int	keyHash The hash value of this entry.
protected String	value The value of this entry.

Method Summary

Modifier and Type	Method and Description
StringBuilder	appendTo(StringBuilder stB) State as String.
Object	clone() A copy of this entry.
int	compareTo(Object o) Compare this entry to another.
boolean	equals(Object o) Compare to other entry.
String	getKey() The key of this Entry.
String	getValue() The value of this Entry.
int	hashCode() Hash code.
static PropMapHelper.Entry	make(CharSequence key, CharSequence value, boolean immutable) Making an entry.
String	setValue(String value) Set / change the value.
String	toString() State as String.

Methods inherited from class java.lang.Object

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

Methods inherited from interface java.util.Map.Entry

comparingByKey, comparingByKey, comparingByValue, comparingByValue

Field Detail

value

protected String value

The value of this entry.

entHash

protected int entHash

The hash code of this entry.

key

protected final String key

The key of this entry.

keyHash

protected final int keyHash

The hash value of this entry.

The positive value only depends on the (final) key. It is calculated by PropMapHelper.posHash(String).

immutable

protected final boolean immutable

The value of this entry is immutable.

Objects of this class either allow any change of value any time or forbid it forever.

Method Detail

getKey

public final String getKey()

The key of this Entry.

Specified by:

getKey in interface Map.Entry<CharSequence,String>

Returns:

a non empty (non white space surrounded) String

See Also:

Map.Entry.getKey()

getValue

public final String getValue()

The value of this Entry.

Specified by:

getValue in interface Map.Entry<CharSequence,String>

Returns:

a String value, may be empty, or null

See Also:

getKey()

make

public static PropMapHelper.Entry make(CharSequence key,
                                       CharSequence value,
                                       boolean immutable)

Making an entry.

key will be stripped from surrounding white space and must (still) not be empty.

If key is OK an PropMapHelper.Entry object is made containing the value. If immutable is true the made PropMapHelper.Entry is (finally) immutable.

Throws:

IllegalArgumentException - if the (trimmed) key is empty

hashCode

public int hashCode()

Hash code.

Returns the entry's hash value as defined by Map.Entry's contract not to be confused with the key's positive hash value (keyHash).

Specified by:

hashCode in interface Map.Entry<CharSequence,String>

Overrides:

hashCode in class Object

See Also:

equals(Object)

equals

public final boolean equals(Object o)

Compare to other entry.

Returns true, if the other object o is of type Map.Entry and key and value are equal to those of this object.

Specified by:

equals in interface Map.Entry<CharSequence,String>

Overrides:

equals in class Object

clone

public Object clone()

A copy of this entry.

Returns a complete copy of this Entry.
If immutable is true, this is returned as copies of (totally and deeply) immutable objects are sheer waste.

Overrides:

clone in class Object

toString

public String toString()

State as String.

Is equivalent to appendTo(null)
.

Overrides:

toString in class Object

appendTo

public StringBuilder appendTo(StringBuilder stB)

State as String.

appends to the StringBuilder stB
" key = value"
making a slight effort towards columns by appending an appropriate number of spaces to a key shorter than 18 characters.

If stB is null, it is generated with a starting capacity of 70.

Parameters:

stB - the StringBuilder to append to; will be made if null

Returns:

stB

setValue

public String setValue(String value)
                throws UnsupportedOperationException

Set / change the value.

Any character sequences, including empty and null are allowed as (new) value.

Is this object constructed as immutable this method called with a value not the same (object) as original value throws a UnsupportedOperationException.

Specified by:

setValue in interface Map.Entry<CharSequence,String>

Returns:

old value

Throws:

UnsupportedOperationException - if immutable and value not the same as the original one

See Also:

Map.Entry.setValue(java.lang.Object)

compareTo

public int compareTo(Object o)

Compare this entry to another.

This method only compares the keys.

Specified by:

compareTo in interface Comparable<Object>

Throws:

ClassCastException - if the other object is no Map.Entry with a String key

See Also:

Comparable.compareTo(java.lang.Object)