org.apache.wicket.markup.html.form

Class LambdaChoiceRenderer<T>

java.lang.Object

org.apache.wicket.markup.html.form.LambdaChoiceRenderer<T>

Type Parameters:

T - The model object type

All Implemented Interfaces:

Serializable, IChoiceRenderer<T>, IDetachable, IClusterable

public class LambdaChoiceRenderer<T>
extends Object
implements IChoiceRenderer<T>

Renders one choice. Separates the 'id' values used for internal representation from 'display values' which are the values shown to the user of components that use this renderer.

Usage:

 new DropDownChoice<User>("users", new Model<User>(selectedUser), listOfUsers,
        new LambdaChoiceRenderer<User>(User::getName))
 

creates a DropDownChoice of users and the display value will be looked up by function (User::getName) and the id the index of the object in the ListOfUsers

 new DropDownChoice<User>("users", new Model<User>(selectedUser), listOfUsers,
        new LambdaChoiceRenderer<User>(User::getName, User::getId))
 

creates a DropDownChoice of users and the display value will be looked up by function (User::getName) and the id will be looked up by the function (User::getId)

Author:

See Also:

Serialized Form

Constructor Summary

Constructors

Constructor and Description
LambdaChoiceRenderer() Constructor.
LambdaChoiceRenderer(org.danekja.java.util.function.serializable.SerializableFunction<T,?> displayExpression) Constructor.
LambdaChoiceRenderer(org.danekja.java.util.function.serializable.SerializableFunction<T,?> displayExpression, org.danekja.java.util.function.serializable.SerializableFunction<T,?> idExpression) Constructor.

Method Summary

Modifier and Type	Method and Description
Object	getDisplayValue(T object) Get the value for displaying to an end user.
String	getIdValue(T object, int index) This method is called to get the id value of an object (used as the value attribute of a choice element) The id can be extracted from the object like a primary key, or if the list is stable you could just return a toString of the index.

Methods inherited from class java.lang.Object

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

Methods inherited from interface org.apache.wicket.markup.html.form.IChoiceRenderer

detach, getObject

Constructor Detail

LambdaChoiceRenderer

public LambdaChoiceRenderer()

Constructor.

When you use this constructor, the display value will be determined by calling toString() on the list object, and the id will be based on the list index. the id value will be the index

LambdaChoiceRenderer

public LambdaChoiceRenderer(org.danekja.java.util.function.serializable.SerializableFunction<T,?> displayExpression)

Constructor.

When you use this constructor, the display value will be determined by executing the given function on the list object, and the id will be based on the list index. The display value will be calculated by the given function

Parameters:

displayExpression - A function to get the display value

LambdaChoiceRenderer

public LambdaChoiceRenderer(org.danekja.java.util.function.serializable.SerializableFunction<T,?> displayExpression,
                            org.danekja.java.util.function.serializable.SerializableFunction<T,?> idExpression)

Constructor.

When you use this constructor, both the id and the display value will be determined by executing the given functions on the list object.

Parameters:

displayExpression - A function to get the display value

idExpression - A function to get the id value

Method Detail

getDisplayValue

public Object getDisplayValue(T object)

Description copied from interface: IChoiceRenderer

Get the value for displaying to an end user.

Specified by:

getDisplayValue in interface IChoiceRenderer<T>

Parameters:

object - the actual object

Returns:

the value meant for displaying to an end user

getIdValue

public String getIdValue(T object,
                         int index)

Description copied from interface: IChoiceRenderer

This method is called to get the id value of an object (used as the value attribute of a choice element) The id can be extracted from the object like a primary key, or if the list is stable you could just return a toString of the index.

Note that the given index can be -1 if the object in question is not contained in the available choices.

Specified by:

getIdValue in interface IChoiceRenderer<T>

Parameters:

object - The object for which the id should be generated

index - The index of the object in the choices list.

Returns:

String