jsonobject.java

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     * Construct a JSONObject from an Object, using reflection to find the
     * public members. The resulting JSONObject's keys will be the strings
     * from the names array, and the values will be the field values associated
     * with those keys in the object. If a key is not found or not visible,
     * then it will not be copied into the new JSONObject.
     * @param object An object that has fields that should be used to make a
     * JSONObject.
     * @param names An array of strings, the names of the fields to be obtained
     * from the object.
     */
    public JSONObject(Object object, String names[]) {
        this();
        Class c = object.getClass();
        for (int i = 0; i < names.length; i += 1) {
            String name = names[i];
        	try {
                Field field = c.getField(name);
                Object value = field.get(object);
                this.put(name, value);
        	} catch (Exception e) {
                /* forget about it */
            }
        }    
    }


    /**
     * Construct a JSONObject from a source JSON text string.
     * This is the most commonly used JSONObject constructor.
     * @param source    A string beginning
     *  with <code>{</code>&nbsp;<small>(left brace)</small> and ending
     *  with <code>}</code>&nbsp;<small>(right brace)</small>.
     * @exception JSONException If there is a syntax error in the source string.
     */
    public JSONObject(String source) throws JSONException {
        this(new JSONTokener(source));
    }


    /**
     * Accumulate values under a key. It is similar to the put method except
     * that if there is already an object stored under the key then a
     * JSONArray is stored under the key to hold all of the accumulated values.
     * If there is already a JSONArray, then the new value is appended to it.
     * In contrast, the put method replaces the previous value.
     * @param key   A key string.
     * @param value An object to be accumulated under the key.
     * @return this.
     * @throws JSONException If the value is an invalid number
     *  or if the key is null.
     */
    public JSONObject accumulate(String key, Object value)
            throws JSONException {
        testValidity(value);
        Object o = opt(key);
        if (o == null) {
            put(key, value instanceof JSONArray ?
                    new JSONArray().put(value) :
                    value);
        } else if (o instanceof JSONArray) {
            ((JSONArray)o).put(value);
        } else {
            put(key, new JSONArray().put(o).put(value));
        }
        return this;
    }


    /**
     * Append values to the array under a key. If the key does not exist in the
     * JSONObject, then the key is put in the JSONObject with its value being a
     * JSONArray containing the value parameter. If the key was already
     * associated with a JSONArray, then the value parameter is appended to it.
     * @param key   A key string.
     * @param value An object to be accumulated under the key.
     * @return this.
     * @throws JSONException If the key is null or if the current value
     *  associated with the key is not a JSONArray.
     */
    public JSONObject append(String key, Object value)
            throws JSONException {
        testValidity(value);
        Object o = opt(key);
        if (o == null) {
            put(key, new JSONArray().put(value));
        } else if (o instanceof JSONArray) {
            put(key, ((JSONArray)o).put(value));
        } else {
            throw new JSONException("JSONObject[" + key +
                    "] is not a JSONArray.");
        }
        return this;
    }


    /**
     * Produce a string from a double. The string "null" will be returned if
     * the number is not finite.
     * @param  d A double.
     * @return A String.
     */
    static public String doubleToString(double d) {
        if (Double.isInfinite(d) || Double.isNaN(d)) {
            return "null";
        }

// Shave off trailing zeros and decimal point, if possible.

        String s = Double.toString(d);
        if (s.indexOf('.') > 0 && s.indexOf('e') < 0 && s.indexOf('E') < 0) {
            while (s.endsWith("0")) {
                s = s.substring(0, s.length() - 1);
            }
            if (s.endsWith(".")) {
                s = s.substring(0, s.length() - 1);
            }
        }
        return s;
    }


    /**
     * Get the value object associated with a key.
     *
     * @param key   A key string.
     * @return      The object associated with the key.
     * @throws   JSONException if the key is not found.
     */
    public Object get(String key) throws JSONException {
        Object o = opt(key);
        if (o == null) {
            throw new JSONException("JSONObject[" + quote(key) +
                    "] not found.");
        }
        return o;
    }


    /**
     * Get the boolean value associated with a key.
     *
     * @param key   A key string.
     * @return      The truth.
     * @throws   JSONException
     *  if the value is not a Boolean or the String "true" or "false".
     */
    public boolean getBoolean(String key) throws JSONException {
        Object o = get(key);
        if (o.equals(Boolean.FALSE) ||
                (o instanceof String &&
                ((String)o).equalsIgnoreCase("false"))) {
            return false;
        } else if (o.equals(Boolean.TRUE) ||
                (o instanceof String &&
                ((String)o).equalsIgnoreCase("true"))) {
            return true;
        }
        throw new JSONException("JSONObject[" + quote(key) +
                "] is not a Boolean.");
    }


    /**
     * Get the double value associated with a key.
     * @param key   A key string.
     * @return      The numeric value.
     * @throws JSONException if the key is not found or
     *  if the value is not a Number object and cannot be converted to a number.
     */
    public double getDouble(String key) throws JSONException {
        Object o = get(key);
        try {
            return o instanceof Number ?
                ((Number)o).doubleValue() :
                Double.valueOf((String)o).doubleValue();
        } catch (Exception e) {
            throw new JSONException("JSONObject[" + quote(key) +
                "] is not a number.");
        }
    }


    /**
     * Get the int value associated with a key. If the number value is too
     * large for an int, it will be clipped.
     *
     * @param key   A key string.
     * @return      The integer value.
     * @throws   JSONException if the key is not found or if the value cannot
     *  be converted to an integer.
     */
    public int getInt(String key) throws JSONException {
        Object o = get(key);
        return o instanceof Number ?
                ((Number)o).intValue() : (int)getDouble(key);
    }


    /**
     * Get the JSONArray value associated with a key.
     *
     * @param key   A key string.
     * @return      A JSONArray which is the value.
     * @throws   JSONException if the key is not found or
     *  if the value is not a JSONArray.
     */
    public JSONArray getJSONArray(String key) throws JSONException {
        Object o = get(key);
        if (o instanceof JSONArray) {
            return (JSONArray)o;
        }
        throw new JSONException("JSONObject[" + quote(key) +
                "] is not a JSONArray.");
    }


    /**
     * Get the JSONObject value associated with a key.
     *
     * @param key   A key string.
     * @return      A JSONObject which is the value.
     * @throws   JSONException if the key is not found or
     *  if the value is not a JSONObject.
     */
    public JSONObject getJSONObject(String key) throws JSONException {
        Object o = get(key);
        if (o instanceof JSONObject) {
            return (JSONObject)o;
        }
        throw new JSONException("JSONObject[" + quote(key) +
                "] is not a JSONObject.");
    }


    /**
     * Get the long value associated with a key. If the number value is too
     * long for a long, it will be clipped.
     *
     * @param key   A key string.
     * @return      The long value.
     * @throws   JSONException if the key is not found or if the value cannot
     *  be converted to a long.
     */
    public long getLong(String key) throws JSONException {
        Object o = get(key);
        return o instanceof Number ?
                ((Number)o).longValue() : (long)getDouble(key);
    }


    /**
     * Get an array of field names from a JSONObject.
     *
     * @return An array of field names, or null if there are no names.
     */
    public static String[] getNames(JSONObject jo) {
    	int length = jo.length();
    	if (length == 0) {
    		return null;
    	}
    	Iterator i = jo.keys();
    	String[] names = new String[length];
    	int j = 0;
    	while (i.hasNext()) {
    		names[j] = (String)i.next();
    		j += 1;
    	}
        return names;
    }


    /**
     * Get an array of field names from an Object.
     *
     * @return An array of field names, or null if there are no names.
     */
    public static String[] getNames(Object object) {
    	if (object == null) {
    		return null;
    	}
    	Class klass = object.getClass();
    	Field[] fields = klass.getFields();
    	int length = fields.length;
    	if (length == 0) {
    		return null;
    	}
    	String[] names = new String[length];
    	for (int i = 0; i < length; i += 1) {
    		names[i] = fields[i].getName();
    	}
        return names;
    }


    /**
     * Get the string associated with a key.
     *
     * @param key   A key string.
     * @return      A string which is the value.
     * @throws   JSONException if the key is not found.
     */
    public String getString(String key) throws JSONException {
        return get(key).toString();
    }


    /**
     * Determine if the JSONObject contains a specific key.
     * @param key   A key string.
     * @return      true if the key exists in the JSONObject.
     */
    public boolean has(String key) {
        return this.map.containsKey(key);
    }


    /**
     * Determine if the value associated with the key is null or if there is
     *  no value.
     * @param key   A key string.
     * @return      true if there is no value associated with the key or if
     *  the value is the JSONObject.NULL object.
     */
    public boolean isNull(String key) {
        return JSONObject.NULL.equals(opt(key));
    }


    /**
     * Get an enumeration of the keys of the JSONObject.
     *
     * @return An iterator of the keys.
     */
    public Iterator keys() {
        return this.map.keySet().iterator();
    }


    /**
     * Get the number of keys stored in the JSONObject.
     *
     * @return The number of keys in the JSONObject.
     */
    public int length() {
        return this.map.size();
    }


    /**
     * Produce a JSONArray containing the names of the elements of this
     * JSONObject.
     * @return A JSONArray containing the key strings, or null if the JSONObject
     * is empty.
     */
    public JSONArray names() {
        JSONArray ja = new JSONArray();
        Iterator  keys = keys();
        while (keys.hasNext()) {
            ja.put(keys.next());
        }
        return ja.length() == 0 ? null : ja;
    }

    /**
     * Produce a string from a Number.
     * @param  n A Number
     * @return A String.