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 * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
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 * This code is distributed in the hope that it will be useful, but WITHOUT
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 * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License
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 * accompanied this code).
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 *
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package javax.script;

import java.util.Map;
import java.util.HashMap;
import java.util.Collection;
import java.util.Set;


A simple implementation of Bindings backed by a HashMap or some other specified Map. 
Author:Mike Grogan
Since:1.6
/**
 * A simple implementation of Bindings backed by
 * a {@code HashMap} or some other specified {@code Map}.
 *
 * @author Mike Grogan
 * @since 1.6
 */
public class SimpleBindings implements Bindings {

    
The Map field stores the attributes. 
/**
     * The {@code Map} field stores the attributes.
     */
    private Map<String,Object> map;

    
Constructor uses an existing Map to store the values. 
Params:
  • m – The Map backing this SimpleBindings.
Throws:
/**
     * Constructor uses an existing {@code Map} to store the values.
     * @param m The {@code Map} backing this {@code SimpleBindings}.
     * @throws NullPointerException if m is null
     */
    public SimpleBindings(Map<String,Object> m) {
        if (m == null) {
            throw new NullPointerException();
        }
        this.map = m;
    }

    
Default constructor uses a HashMap. 
/**
     * Default constructor uses a {@code HashMap}.
     */
    public SimpleBindings() {
        this(new HashMap<String,Object>());
    }

    
Sets the specified key/value in the underlying map field. 
Params:
  • name – Name of value
  • value – Value to set.
Throws:
Returns:Previous value for the specified key.  Returns null if key was previously
unset.
/**
     * Sets the specified key/value in the underlying {@code map} field.
     *
     * @param name Name of value
     * @param value Value to set.
     *
     * @return Previous value for the specified key.  Returns null if key was previously
     * unset.
     *
     * @throws NullPointerException if the name is null.
     * @throws IllegalArgumentException if the name is empty.
     */
    public Object put(String name, Object value) {
        checkKey(name);
        return map.put(name,value);
    }

    
putAll is implemented using Map.putAll. 
Params:
  • toMerge – The Map of values to add.
Throws:
/**
     * {@code putAll} is implemented using {@code Map.putAll}.
     *
     * @param toMerge The {@code Map} of values to add.
     *
     * @throws NullPointerException
     *         if toMerge map is null or if some key in the map is null.
     * @throws IllegalArgumentException
     *         if some key in the map is an empty String.
     */
    public void putAll(Map<? extends String, ? extends Object> toMerge) {
        if (toMerge == null) {
            throw new NullPointerException("toMerge map is null");
        }
        for (Map.Entry<? extends String, ? extends Object> entry : toMerge.entrySet()) {
            String key = entry.getKey();
            checkKey(key);
            put(key, entry.getValue());
        }
    }

    
{@inheritDoc} 
/** {@inheritDoc} */
    public void clear() {
        map.clear();
    }

    
Returns true if this map contains a mapping for the specified key. More formally, returns true if and only if this map contains a mapping for a key k such that (key==null ? k==null : key.equals(k)). (There can be at most one such mapping.) 
Params:
  • key – key whose presence in this map is to be tested.
Throws:
Returns:true if this map contains a mapping for the specified key.
/**
     * Returns {@code true} if this map contains a mapping for the specified
     * key.  More formally, returns {@code true} if and only if
     * this map contains a mapping for a key {@code k} such that
     * {@code (key==null ? k==null : key.equals(k))}.  (There can be
     * at most one such mapping.)
     *
     * @param key key whose presence in this map is to be tested.
     * @return {@code true} if this map contains a mapping for the specified
     *         key.
     *
     * @throws NullPointerException if key is null
     * @throws ClassCastException if key is not String
     * @throws IllegalArgumentException if key is empty String
     */
    public boolean containsKey(Object key) {
        checkKey(key);
        return map.containsKey(key);
    }

    
{@inheritDoc} 
/** {@inheritDoc} */
    public boolean containsValue(Object value) {
        return map.containsValue(value);
    }

    
{@inheritDoc} 
/** {@inheritDoc} */
    public Set<Map.Entry<String, Object>> entrySet() {
        return map.entrySet();
    }

    
Returns the value to which this map maps the specified key. Returns null if the map contains no mapping for this key. A return value of null does not necessarily indicate that the map contains no mapping for the key; it's also possible that the map explicitly maps the key to null. The containsKey operation may be used to distinguish these two cases. 
More formally, if this map contains a mapping from a key k to a value v such that (key==null ? k==null : key.equals(k)), then this method returns v; otherwise it returns null. (There can be at most one such mapping.) 
Params:
  • key – key whose associated value is to be returned.
Throws:
Returns:the value to which this map maps the specified key, or null if the map contains no mapping for this key.
/**
     * Returns the value to which this map maps the specified key.  Returns
     * {@code null} if the map contains no mapping for this key.  A return
     * value of {@code null} does not <i>necessarily</i> indicate that the
     * map contains no mapping for the key; it's also possible that the map
     * explicitly maps the key to {@code null}.  The {@code containsKey}
     * operation may be used to distinguish these two cases.
     *
     * <p>More formally, if this map contains a mapping from a key
     * {@code k} to a value {@code v} such that
     * {@code (key==null ? k==null : key.equals(k))},
     * then this method returns {@code v}; otherwise
     * it returns {@code null}.  (There can be at most one such mapping.)
     *
     * @param key key whose associated value is to be returned.
     * @return the value to which this map maps the specified key, or
     *         {@code null} if the map contains no mapping for this key.
     *
     * @throws NullPointerException if key is null
     * @throws ClassCastException if key is not String
     * @throws IllegalArgumentException if key is empty String
     */
    public Object get(Object key) {
        checkKey(key);
        return map.get(key);
    }

    
{@inheritDoc} 
/** {@inheritDoc} */
    public boolean isEmpty() {
        return map.isEmpty();
    }

    
{@inheritDoc} 
/** {@inheritDoc} */
    public Set<String> keySet() {
        return map.keySet();
    }

    
Removes the mapping for this key from this map if it is present (optional operation). More formally, if this map contains a mapping from key k to value v such that (key==null ?  k==null : key.equals(k)), that mapping is removed. (The map can contain at most one such mapping.) 
Returns the value to which the map previously associated the key, or null if the map contained no mapping for this key. (A null return can also indicate that the map previously associated null with the specified key if the implementation supports null values.) The map will not contain a mapping for the specified key once the call returns. 
Params:
  • key – key whose mapping is to be removed from the map.
Throws:
Returns:previous value associated with specified key, or null if there was no mapping for key.
/**
     * Removes the mapping for this key from this map if it is present
     * (optional operation).   More formally, if this map contains a mapping
     * from key {@code k} to value {@code v} such that
     * {@code (key==null ?  k==null : key.equals(k))}, that mapping
     * is removed.  (The map can contain at most one such mapping.)
     *
     * <p>Returns the value to which the map previously associated the key, or
     * {@code null} if the map contained no mapping for this key.  (A
     * {@code null} return can also indicate that the map previously
     * associated {@code null} with the specified key if the implementation
     * supports {@code null} values.)  The map will not contain a mapping for
     * the specified  key once the call returns.
     *
     * @param key key whose mapping is to be removed from the map.
     * @return previous value associated with specified key, or {@code null}
     *         if there was no mapping for key.
     *
     * @throws NullPointerException if key is null
     * @throws ClassCastException if key is not String
     * @throws IllegalArgumentException if key is empty String
     */
    public Object remove(Object key) {
        checkKey(key);
        return map.remove(key);
    }

    
{@inheritDoc} 
/** {@inheritDoc} */
    public int size() {
        return map.size();
    }

    
{@inheritDoc} 
/** {@inheritDoc} */
    public Collection<Object> values() {
        return map.values();
    }

    private void checkKey(Object key) {
        if (key == null) {
            throw new NullPointerException("key can not be null");
        }
        if (!(key instanceof String)) {
            throw new ClassCastException("key should be a String");
        }
        if (key.equals("")) {
            throw new IllegalArgumentException("key can not be empty");
        }
    }
}