java.lang.Object
- org.apache.commons.collections.keyvalue.MultiKey

All Implemented Interfaces:

java.io.Serializable
```
@Deprecated(since="2021-04-30")
public class MultiKey
extends java.lang.Object
implements java.io.Serializable
```
Deprecated.
Commons Collections 3 is in maintenance mode. Commons Collections 4 should be used instead.
A MultiKey allows multiple map keys to be merged together.
The purpose of this class is to avoid the need to write code to handle maps of maps. An example might be the need to lookup a filename by key and locale. The typical solution might be nested maps. This class can be used instead by creating an instance passing in the key and locale.
Example usage:
```
  // populate map with data mapping key+locale to localizedText
  Map map = new HashMap();
  MultiKey multiKey = new MultiKey(key, locale);
  map.put(multiKey, localizedText);

  // later retireve the localized text
  MultiKey multiKey = new MultiKey(key, locale);
  String localizedText = (String) map.get(multiKey);
  
```
Since:

Commons Collections 3.0

See Also:

Serialized Form

Constructor Summary

Constructors
Constructor	Description
`MultiKey(java.lang.Object[] keys)`	Deprecated. Constructor taking an array of keys which is cloned.
`MultiKey(java.lang.Object[] keys, boolean makeClone)`	Deprecated. Constructor taking an array of keys, optionally choosing whether to clone.
`MultiKey(java.lang.Object key1, java.lang.Object key2)`	Deprecated. Constructor taking two keys.
`MultiKey(java.lang.Object key1, java.lang.Object key2, java.lang.Object key3)`	Deprecated. Constructor taking three keys.
`MultiKey(java.lang.Object key1, java.lang.Object key2, java.lang.Object key3, java.lang.Object key4)`	Deprecated. Constructor taking four keys.
`MultiKey(java.lang.Object key1, java.lang.Object key2, java.lang.Object key3, java.lang.Object key4, java.lang.Object key5)`	Deprecated. Constructor taking five keys.

Method Summary

All Methods Instance Methods Concrete Methods Deprecated Methods
Modifier and Type	Method	Description
`boolean`	`equals(java.lang.Object other)`	Deprecated. Compares this object to another.
`java.lang.Object`	`getKey(int index)`	Deprecated. Gets the key at the specified index.
`java.lang.Object[]`	`getKeys()`	Deprecated. Gets a clone of the array of keys.
`int`	`hashCode()`	Deprecated. Gets the combined hash code that is computed from all the keys.
`int`	`size()`	Deprecated. Gets the size of the list of keys.
`java.lang.String`	`toString()`	Deprecated. Gets a debugging string version of the key.

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

- Constructor Detail
  - MultiKey
```
public MultiKey(java.lang.Object key1,
                java.lang.Object key2)
```
    Deprecated.
    
    Constructor taking two keys.
    The keys should be immutable If they are not then they must not be changed after adding to the MultiKey.
    
    Parameters:
    
    key1 - the first key
    
    key2 - the second key
  - MultiKey
```
public MultiKey(java.lang.Object key1,
                java.lang.Object key2,
                java.lang.Object key3)
```
    Deprecated.
    
    Constructor taking three keys.
    The keys should be immutable If they are not then they must not be changed after adding to the MultiKey.
    
    Parameters:
    
    key1 - the first key
    
    key2 - the second key
    
    key3 - the third key
  - MultiKey
```
public MultiKey(java.lang.Object key1,
                java.lang.Object key2,
                java.lang.Object key3,
                java.lang.Object key4)
```
    Deprecated.
    
    Constructor taking four keys.
    The keys should be immutable If they are not then they must not be changed after adding to the MultiKey.
    
    Parameters:
    
    key1 - the first key
    
    key2 - the second key
    
    key3 - the third key
    
    key4 - the fourth key
  - MultiKey
```
public MultiKey(java.lang.Object key1,
                java.lang.Object key2,
                java.lang.Object key3,
                java.lang.Object key4,
                java.lang.Object key5)
```
    Deprecated.
    
    Constructor taking five keys.
    The keys should be immutable If they are not then they must not be changed after adding to the MultiKey.
    
    Parameters:
    
    key1 - the first key
    
    key2 - the second key
    
    key3 - the third key
    
    key4 - the fourth key
    
    key5 - the fifth key
  - MultiKey
```
public MultiKey(java.lang.Object[] keys)
```
    Deprecated.
    
    Constructor taking an array of keys which is cloned.
    The keys should be immutable If they are not then they must not be changed after adding to the MultiKey.
    This is equivalent to new MultiKey(keys, true).
    
    Parameters:
    
    keys - the array of keys, not null
    
    Throws:
    
    java.lang.IllegalArgumentException - if the key array is null
  - MultiKey
```
public MultiKey(java.lang.Object[] keys,
                boolean makeClone)
```
    Deprecated.
    Constructor taking an array of keys, optionally choosing whether to clone.
    If the array is not cloned, then it must not be modified.
    This method is public for performance reasons only, to avoid a clone. The hashcode is calculated once here in this method. Therefore, changing the array passed in would not change the hashcode but would change the equals method, which is a bug.
    This is the only fully safe usage of this constructor, as the object array is never made available in a variable:
    new MultiKey(new Object[] {...}, false);
    
    The keys should be immutable If they are not then they must not be changed after adding to the MultiKey.
    Parameters:
    
    keys - the array of keys, not null
    
    makeClone - true to clone the array, false to assign it
    
    Throws:
    
    java.lang.IllegalArgumentException - if the key array is null
    
    Since:
    
    Commons Collections 3.1
- Method Detail
  - getKeys
```
public java.lang.Object[] getKeys()
```
    Deprecated.
    
    Gets a clone of the array of keys.
    The keys should be immutable If they are not then they must not be changed.
    
    Returns:
    
    the individual keys
  - getKey
```
public java.lang.Object getKey(int index)
```
    Deprecated.
    
    Gets the key at the specified index.
    The key should be immutable. If it is not then it must not be changed.
    
    Parameters:
    
    index - the index to retrieve
    
    Returns:
    
    the key at the index
    
    Throws:
    
    java.lang.IndexOutOfBoundsException - if the index is invalid
    
    Since:
    
    Commons Collections 3.1
  - size
```
public int size()
```
    Deprecated.
    
    Gets the size of the list of keys.
    
    Returns:
    
    the size of the list of keys
    
    Since:
    
    Commons Collections 3.1
  - equals
```
public boolean equals(java.lang.Object other)
```
    Deprecated.
    
    Compares this object to another.
    To be equal, the other object must be a MultiKey with the same number of keys which are also equal.
    
    Overrides:
    
    equals in class java.lang.Object
    
    Parameters:
    
    other - the other object to compare to
    
    Returns:
    
    true if equal
  - hashCode
```
public int hashCode()
```
    Deprecated.
    
    Gets the combined hash code that is computed from all the keys.
    This value is computed once and then cached, so elements should not change their hash codes once created (note that this is the same constraint that would be used if the individual keys elements were themselves Map keys.
    
    Overrides:
    
    hashCode in class java.lang.Object
    
    Returns:
    
    the hash code
  - toString
```
public java.lang.String toString()
```
    Deprecated.
    
    Gets a debugging string version of the key.
    
    Overrides:
    
    toString in class java.lang.Object
    
    Returns:
    
    a debugging string

Class MultiKey

Constructor Summary

Method Summary

Methods inherited from class java.lang.Object

Constructor Detail

MultiKey

MultiKey

MultiKey

MultiKey

MultiKey

MultiKey

Method Detail

getKeys

getKey

size

equals

hashCode

toString