net.sf.mmm.util.pojo.path.api

Class TypedProperty<T>

java.lang.Object

net.sf.mmm.util.pojo.path.api.TypedProperty<T>

Type Parameters:

T - is the generic type of the property.

All Implemented Interfaces:

AttributeReadTitle<String>, PojoPropertyPath

public class TypedProperty<T>
extends Object
implements PojoPropertyPath, AttributeReadTitle<String>

This class represents a typed property (typically from a java bean). The raw property name is called segment. In case the property is not directly accessed but via traversing multiple properties of an object-web, then getParentPath() will return the path to the parent object containing the actual property identified by getSegment(). The entire path including the segment is accessible via getPojoPath(). The actual type of the property may be returned by getPropertyType() (if provided at construction time) but is typically omitted.
Example:

 public interface MyObject {

   TypedProperty<String> PROPERTY_NAME = new TypedProperty<>(String.class, "name");

   TypedProperty<Integer> PROPERTY_AGE = new TypedProperty<>(Integer.class, "age");

   TypedProperty<String> PROPERTY_ADDRESS_CITY = new TypedProperty<>(String.class, "address", MyAddress.TYPED_PROPERTY_CITY);

   String getName();

   // may also return int instead of Integer...
   Integer getAge();

   MyAddress getAddress();
 }
 

Now assuming that you have a generic signature like this:

 public interface Query {
   <T> addCondition(TypedProperty<T> property, Operator operator, T value);
 }
 

Then you can combine these two things as following:

 Query myQuery = newQuery();
 myQuery.addCondition(MyObject.TYPED_PROPERTY_AGE, Operator.GREATER_THAN, Integer.valueOf(42));
 

Now in case you have to change the type of the property "age" for whatever reason to some other type, then you change the type of the getter in parallel with the according TypedProperty constant. In the same moment the compiler will reject the above code to create the query and you will be able to fix all places where generic access to the "age" property takes place. When using simple string references for property access (addCondition(String, Operator, Object)) instead you would have to pray that you did NOT miss anything in the code or you get errors in production at runtime.

Since:

3.0.0

Author:

Joerg Hohwiller (hohwille at users.sourceforge.net)

Field Summary

Fields

Modifier and Type	Field and Description
private String	parentPath
private String	pojoPath
private Class<T>	propertyType
private String	segment
private String	title

Fields inherited from interface net.sf.mmm.util.pojo.path.api.PojoPropertyPath

SEPARATOR

Constructor Summary

Constructors

Constructor and Description
TypedProperty(Class<T> propertyType, String segment) The constructor.
TypedProperty(Class<T> propertyType, String segment, String parentPath) The constructor.
TypedProperty(String segment) The constructor.
TypedProperty(String title, Class<T> propertyType, String segment) The constructor.
TypedProperty(String title, Class<T> propertyType, String segment, String parentPath) The constructor.
TypedProperty(String segment, String parentPath) The constructor.
TypedProperty(TypedProperty<T> property, String path) The constructor.

Method Summary

Modifier and Type	Method and Description
static void	appendPath(StringBuilder buffer, String... segments) This method appends the pojo property path specified by the given segments to the given buffer.
static String	createPath(String... segments) This method creates a pojo property path specified by the given segments.
String	getParentPath() This method gets the parent-path of this path.
String	getPojoPath() This method gets the actual Pojo path represented by this object.
Class<T>	getPropertyType() This method gets the type of this property.
String	getSegment() This method gets the last segment of this current Pojo path.
String	getTitle() This title is used to display the property name to end-users.
String	toString()

Methods inherited from class java.lang.Object

clone, equals, finalize, getClass, hashCode, notify, notifyAll, wait, wait, wait

Field Detail

segment

private final String segment

See Also:

getSegment()

pojoPath

private final String pojoPath

See Also:

getPojoPath()

propertyType

private final Class<T> propertyType

See Also:

getPropertyType()

parentPath

private final String parentPath

See Also:

getParentPath()

title

private final String title

See Also:

getTitle()

Constructor Detail

TypedProperty

public TypedProperty(String segment)

The constructor.

Parameters:

segment - is the segment and also the entire pojo path.

TypedProperty

public TypedProperty(String segment,
                     String parentPath)

The constructor.

Parameters:

segment - - see getSegment().

parentPath - - see getParentPath() and createPath(String...).

TypedProperty

public TypedProperty(Class<T> propertyType,
                     String segment)

The constructor.

Parameters:

propertyType - - see getPropertyType().

segment - is the segment and also the entire pojo path.

TypedProperty

public TypedProperty(String title,
                     Class<T> propertyType,
                     String segment)

The constructor.

Parameters:

title - - see getTitle().

propertyType - - see getPropertyType().

segment - is the segment and also the entire pojo path.

TypedProperty

public TypedProperty(TypedProperty<T> property,
                     String path)

The constructor.

Parameters:

property - is the existing TypedProperty to create as nested property.

path - is the parent path to the given property. See also createPath(String...).

TypedProperty

public TypedProperty(Class<T> propertyType,
                     String segment,
                     String parentPath)

The constructor.

Parameters:

propertyType - - see getPropertyType().

segment - - see getSegment().

parentPath - - see getParentPath() and createPath(String...).

TypedProperty

public TypedProperty(String title,
                     Class<T> propertyType,
                     String segment,
                     String parentPath)

The constructor.

Parameters:

title - - see getTitle().

propertyType - - see getPropertyType().

segment - - see getSegment().

parentPath - - see getParentPath() and createPath(String...).

Method Detail

getSegment

public String getSegment()

This method gets the last segment of this current Pojo path. E.g. if this path represents "foo.bar.property" then this method would return "property".

Specified by:

getSegment in interface PojoPropertyPath

Returns:

the last segment.

getTitle

public String getTitle()

This title is used to display the property name to end-users. If not explicitly specified, it will be the same as the segment. For NLS the title will be used as key for resource bundles (outside of this class) and should therefore be stable and not contain special characters. This method gets the title of this object.
NOTE:
For generic usage you need to use Object.toString() of the result if NOT null

Specified by:

getTitle in interface AttributeReadTitle<String>

Returns:

the title or null if not set. The string-representation of the result (if NOT null) needs to be suitable for end-users.

getPojoPath

public String getPojoPath()

This method gets the actual Pojo path represented by this object. As an example this method may return "foo.bar.property".

Specified by:

getPojoPath in interface PojoPropertyPath

Returns:

the actual PojoPropertyPath.

getParentPath

public String getParentPath()

This method gets the parent-path of this path.
E.g. if this path represents "foo.bar.property" then this method would return "foo.bar".

Specified by:

getParentPath in interface PojoPropertyPath

Returns:

the parent-path or null if this is the root-segment.

getPropertyType

public Class<T> getPropertyType()

This method gets the type of this property.
ATTENTION:
The actual type is optional. The major concept is the generic that ensures type safe access as compile time check. If some API takes a TypedProperty and requires the property type to be set this must be explicitly documented. By default the type will be omitted, to lower the barrier of defining a TypedProperty for each property of an entity.

Returns:

the type or null if NOT available.

toString

public String toString()

Overrides:

toString in class Object

createPath

public static String createPath(String... segments)

This method creates a pojo property path specified by the given segments.

Parameters:

segments - is the array of properties to concat with dot (".").

Returns:

the resulting property path as String.

appendPath

public static void appendPath(StringBuilder buffer,
                              String... segments)

This method appends the pojo property path specified by the given segments to the given buffer.

Parameters:

buffer - is the StringBuilder to append to.

segments - are the path segments for the property.