MetaDataKey (Wicket Core 9.16.0 API)

java.lang.Object
- org.apache.wicket.MetaDataKey<T>

Type Parameters:

T - The type of the object which is stored

All Implemented Interfaces:

Serializable, org.apache.wicket.util.io.IClusterable
```
public abstract class MetaDataKey<T>
extends Object
implements org.apache.wicket.util.io.IClusterable
```
A key to a piece of metadata associated with a Component, Session or Application at runtime. The key contains type information that can be used to check the type of any metadata value for the key when the value is set. MetaDataKey is abstract in order to force the creation of a subtype. That subtype is used to test for identity when looking for the metadata because actual object identity would suffer from problems under serialization. So, the correct way to declare a MetaDataKey is like this:
```
 
 public static final MetaDataKey<Role> ROLE = new MetaDataKey<Role>() { };
 
 
```
Author:

Jonathan Locke

See Also:

Session.getMetaData(MetaDataKey), Component.getMetaData(MetaDataKey), Application.getMetaData(MetaDataKey), Serialized Form

Constructor Summary

Constructors
Constructor Description

MetaDataKey()
Constructor.

Method Summary

All Methods Instance Methods Concrete Methods
Modifier and Type	Method	Description
`boolean`	`equals(Object obj)`
`T`	`get(MetaDataEntry<?>[] metaData)`
`int`	`hashCode()`
`MetaDataEntry<?>[]`	`set(MetaDataEntry<?>[] metaData, Object object)`
`String`	`toString()`

Methods inherited from class java.lang.Object
clone, finalize, getClass, notify, notifyAll, wait, wait, wait

- Constructor Detail
  - MetaDataKey
```
public MetaDataKey()
```
    Constructor.
- Method Detail
  - hashCode
```
public int hashCode()
```
    Overrides:
    
    hashCode in class Object
  - equals
```
public boolean equals(Object obj)
```
    Overrides:
    
    equals in class Object
    
    See Also:
    
    Object.equals(java.lang.Object)
  - get
```
public T get(MetaDataEntry<?>[] metaData)
```
    Parameters:
    
    metaData - Array of metadata to search
    
    Returns:
    
    The entry value
  - set
```
public MetaDataEntry<?>[] set(MetaDataEntry<?>[] metaData,
                              Object object)
```
    Parameters:
    
    metaData - The array of metadata
    
    object - The object to set, null to remove
    
    Returns:
    
    Any new metadata array (if it was reallocated)
  - toString
```
public String toString()
```
    Overrides:
    
    toString in class Object
    
    See Also:
    
    Object.toString()