SimpleHash (FreeMarker 2.3.23 API)

java.lang.Object
- freemarker.template.WrappingTemplateModel
- - freemarker.template.SimpleHash

All Implemented Interfaces:

TemplateHashModel, TemplateHashModelEx, TemplateModel, Serializable

Direct Known Subclasses:

AllHttpScopesHashModel, Environment.Namespace
```
public class SimpleHash
extends WrappingTemplateModel
implements TemplateHashModelEx, Serializable
```
A simple implementation of the TemplateHashModelEx interface, using its own underlying Map or SortedMap for storing the hash entries. If you are wrapping an already existing Map, you should certainly use DefaultMapAdapter instead (see comparison below).
This class is thread-safe if you don't call modifying methods (like put(String, Object), remove(String), etc.) after you have made the object available for multiple threads (assuming you have published it safely to the other threads; see JSR-133 Java Memory Model). These methods aren't called by FreeMarker, so it's usually not a concern.
SimpleHash VS DefaultMapAdapter - Which to use when?
For a Map that exists regardless of FreeMarker, only you need to access it from templates, DefaultMapAdapter should be the default choice, as it reflects the exact behavior of the underlying Map (no surprises), can be unwrapped to the originally wrapped object (important when passing it to Java methods from the template), and has more predictable performance (no spikes).
For a hash that's made specifically to be used from templates, creating an empty SimpleHash then filling it with put(String, Object) is usually the way to go, as the resulting hash is significantly faster to read from templates than a DefaultMapAdapter (though it's somewhat slower to read from a plain Java method to which it had to be passed adapted to a Map).
If regardless of which of the above two cases stand, you just need to (or more convenient to) create the hash from a Map (via SimpleHash(Map, ObjectWrapper) or SimpleHash(Map, ObjectWrapper)), which will be the faster depends on how many times will the same Map entry be read from the template(s) later, on average. If, on average, you read each entry for more than 4 times, SimpleHash will be most certainly faster, but if for 2 times or less (and especially if not at all) then DefaultMapAdapter will be. Before choosing based on performance though, pay attention to the behavioral differences; SimpleHash will shallow-copy the original Map at construction time, so key order will be lost in some cases, and it won't reflect Map content changes after the SimpleHash construction, also SimpleHash can't be unwrapped to the original Map instance.

See Also:

DefaultMapAdapter, TemplateHashModelEx, Serialized Form

Field Summary
- Fields inherited from interface freemarker.template.TemplateModel
  NOTHING

Constructor Summary

Constructors
Constructor and Description
`SimpleHash()` Deprecated. Use `SimpleHash(ObjectWrapper)`
`SimpleHash(Map map)` Deprecated. Use `SimpleHash(Map, ObjectWrapper)`
`SimpleHash(Map map, ObjectWrapper wrapper)` Creates a new hash by shallow-coping (possibly cloning) the underlying map; in many applications you should use `DefaultMapAdapter` instead.
`SimpleHash(ObjectWrapper wrapper)` Creates an empty simple hash using the specified object wrapper.

Method Summary

All Methods Instance Methods Concrete Methods
Modifier and Type	Method and Description
`boolean`	`containsKey(String key)` Tells if the map contains a key or not, regardless if the associated value is `null` or not.
`protected Map`	`copyMap(Map map)`
`TemplateModel`	`get(String key)` Gets a `TemplateModel` from the hash.
`boolean`	`isEmpty()`
`TemplateCollectionModel`	`keys()`
`void`	`put(String key, boolean b)` Puts a boolean in the map
`void`	`put(String key, Object value)` Adds a key-value entry to this hash.
`void`	`putAll(Map m)` Adds all the key/value entries in the map
`void`	`remove(String key)` Removes the given key from the underlying map.
`int`	`size()`
`SimpleHash`	`synchronizedWrapper()`
`Map`	`toMap()` Note that this method creates and returns a deep-copy of the underlying hash used internally.
`String`	`toString()` Returns the `toString()` of the underlying `Map`.
`TemplateCollectionModel`	`values()`

Methods inherited from class freemarker.template.WrappingTemplateModel
getDefaultObjectWrapper, getObjectWrapper, setDefaultObjectWrapper, setObjectWrapper, wrap

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

- Constructor Detail
  - SimpleHash
```
public SimpleHash()
```
    Deprecated. Use SimpleHash(ObjectWrapper)
    
    Constructs an empty hash that uses the default wrapper set in WrappingTemplateModel.setDefaultObjectWrapper(ObjectWrapper).
  - SimpleHash
```
public SimpleHash(Map map)
```
    Deprecated. Use SimpleHash(Map, ObjectWrapper)
    
    Creates a new simple hash with the copy of the underlying map and the default wrapper set in WrappingTemplateModel.setDefaultObjectWrapper(ObjectWrapper).
    
    Parameters:
    
    map - The Map to use for the key/value pairs. It makes a copy for internal use. If the map implements the SortedMap interface, the internal copy will be a TreeMap, otherwise it will be a HashMap.
  - SimpleHash
```
public SimpleHash(ObjectWrapper wrapper)
```
    Creates an empty simple hash using the specified object wrapper.
    
    Parameters:
    
    wrapper - The object wrapper to use to wrap objects into TemplateModel instances. If null, the default wrapper set in WrappingTemplateModel.setDefaultObjectWrapper(ObjectWrapper) is used.
  - SimpleHash
```
public SimpleHash(Map map,
                  ObjectWrapper wrapper)
```
    Creates a new hash by shallow-coping (possibly cloning) the underlying map; in many applications you should use DefaultMapAdapter instead.
    
    Parameters:
    
    map - The Map to use for the key/value pairs. It makes a copy for internal use. If the map implements the SortedMap interface, the internal copy will be a TreeMap, otherwise it will be a
    
    wrapper - The object wrapper to use to wrap contained objects into TemplateModel instances. Using null is deprecated but allowed, in which case the deprecated default wrapper set in WrappingTemplateModel.setDefaultObjectWrapper(ObjectWrapper) is used.
- Method Detail
  - copyMap
```
protected Map copyMap(Map map)
```
  - put
```
public void put(String key,
                Object value)
```
    Adds a key-value entry to this hash.
    
    Parameters:
    
    key - The name by which the object is identified in the template.
    
    value - The value to which the name will be associated. This will only be wrapped to TemplateModel lazily when it's first read.
  - put
```
public void put(String key,
                boolean b)
```
    Puts a boolean in the map
    
    Parameters:
    
    key - the name by which the resulting TemplateModel is identified in the template.
    
    b - the boolean to store.
  - get
```
public TemplateModel get(String key)
                  throws TemplateModelException
```
    Description copied from interface: TemplateHashModel
    
    Gets a TemplateModel from the hash.
    
    Specified by:
    
    get in interface TemplateHashModel
    
    Parameters:
    
    key - the name by which the TemplateModel is identified in the template.
    
    Returns:
    
    the TemplateModel referred to by the key, or null if not found.
    
    Throws:
    
    TemplateModelException
  - containsKey
```
public boolean containsKey(String key)
```
    Tells if the map contains a key or not, regardless if the associated value is null or not.
    
    Since:
    
    2.3.20
  - remove
```
public void remove(String key)
```
    Removes the given key from the underlying map.
    
    Parameters:
    
    key - the key to be removed
  - putAll
```
public void putAll(Map m)
```
    Adds all the key/value entries in the map
    
    Parameters:
    
    m - the map with the entries to add, the keys are assumed to be strings.
  - toMap
```
public Map toMap()
          throws TemplateModelException
```
    Note that this method creates and returns a deep-copy of the underlying hash used internally. This could be a gotcha for some people at some point who want to alter something in the data model, but we should maintain our immutability semantics (at least using default SimpleXXX wrappers) for the data model. It will recursively unwrap the stuff in the underlying container.
    
    Throws:
    
    TemplateModelException
  - toString
```
public String toString()
```
    Returns the toString() of the underlying Map.
    
    Overrides:
    
    toString in class Object
  - size
```
public int size()
```
    Specified by:
    
    size in interface TemplateHashModelEx
    
    Returns:
    
    the number of key/value mappings in the hash.
  - isEmpty
```
public boolean isEmpty()
```
    Specified by:
    
    isEmpty in interface TemplateHashModel
  - keys
```
public TemplateCollectionModel keys()
```
    Specified by:
    
    keys in interface TemplateHashModelEx
    
    Returns:
    
    a collection containing the keys in the hash. Every element of the returned collection must implement the TemplateScalarModel (as the keys of hashes are always strings).
  - values
```
public TemplateCollectionModel values()
```
    Specified by:
    
    values in interface TemplateHashModelEx
    
    Returns:
    
    a collection containing the values in the hash. The elements of the returned collection can be any kind of TemplateModel-s.
  - synchronizedWrapper
```
public SimpleHash synchronizedWrapper()
```

Class SimpleHash

Field Summary

Fields inherited from interface freemarker.template.TemplateModel

Constructor Summary

Method Summary

Methods inherited from class freemarker.template.WrappingTemplateModel

Methods inherited from class java.lang.Object

Constructor Detail

SimpleHash

SimpleHash

SimpleHash

SimpleHash

Method Detail

copyMap

put

put

get

containsKey

remove

putAll

toMap

toString

size

isEmpty

keys

values

synchronizedWrapper