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1823 lines (1716 loc) · 61 KB
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package org.json;
/*
Copyright (c) 2002 JSON.org
Permission is hereby granted, free of charge, to any person obtaining a copy
of this software and associated documentation files (the "Software"), to deal
in the Software without restriction, including without limitation the rights
to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
copies of the Software, and to permit persons to whom the Software is
furnished to do so, subject to the following conditions:
The above copyright notice and this permission notice shall be included in all
copies or substantial portions of the Software.
The Software shall be used for Good, not Evil.
THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
SOFTWARE.
*/
import java.io.IOException;
import java.io.StringWriter;
import java.io.Writer;
import java.lang.reflect.Field;
import java.lang.reflect.Method;
import java.lang.reflect.Modifier;
import java.math.*;
import java.util.Collection;
import java.util.Enumeration;
import java.util.HashMap;
import java.util.Iterator;
import java.util.Locale;
import java.util.Map;
import java.util.ResourceBundle;
import java.util.Set;
/**
* A JSONObject is an unordered collection of name/value pairs. Its external
* form is a string wrapped in curly braces with colons between the names and
* values, and commas between the values and names. The internal form is an
* object having <code>get</code> and <code>opt</code> methods for accessing
* the values by name, and <code>put</code> methods for adding or replacing
* values by name. The values can be any of these types: <code>Boolean</code>,
* <code>JSONArray</code>, <code>JSONObject</code>, <code>Number</code>,
* <code>String</code>, or the <code>JSONObject.NULL</code> object. A
* JSONObject constructor can be used to convert an external form JSON text
* into an internal form whose values can be retrieved with the
* <code>get</code> and <code>opt</code> methods, or to convert values into a
* JSON text using the <code>put</code> and <code>toString</code> methods. A
* <code>get</code> method returns a value if one can be found, and throws an
* exception if one cannot be found. An <code>opt</code> method returns a
* default value instead of throwing an exception, and so is useful for
* obtaining optional values.
* <p>
* The generic <code>get()</code> and <code>opt()</code> methods return an
* object, which you can cast or query for type. There are also typed
* <code>get</code> and <code>opt</code> methods that do type checking and type
* coercion for you. The opt methods differ from the get methods in that they
* do not throw. Instead, they return a specified value, such as null.
* <p>
* The <code>put</code> methods add or replace values in an object. For
* example,
*
* <pre>
* myString = new JSONObject()
* .put("JSON", "Hello, World!").toString();
* </pre>
*
* produces the string <code>{"JSON": "Hello, World"}</code>.
* <p>
* The texts produced by the <code>toString</code> methods strictly conform to
* the JSON syntax rules. The constructors are more forgiving in the texts they
* will accept:
* <ul>
* <li>An extra <code>,</code> <small>(comma)</small> may appear just
* before the closing brace.</li>
* <li>Strings may be quoted with <code>'</code> <small>(single
* quote)</small>.</li>
* <li>Strings do not need to be quoted at all if they do not begin with a
* quote or single quote, and if they do not contain leading or trailing
* spaces, and if they do not contain any of these characters:
* <code>{ } [ ] / \ : , #</code> and if they do not look like numbers and
* if they are not the reserved words <code>true</code>, <code>false</code>,
* or <code>null</code>.</li>
* </ul>
*
* @author JSON.org
* @version 2015-12-09
*/
public class JSONObject extends HashMap<String, Object> {
/**
* JSONObject.NULL is equivalent to the value that JavaScript calls null,
* whilst Java's null is equivalent to the value that JavaScript calls
* undefined.
*/
private static final class Null {
/**
* There is only intended to be a single instance of the NULL object,
* so the clone method returns itself.
*
* @return NULL.
*/
@Override
protected final Object clone() {
return this;
}
/**
* A Null object is equal to the null value and to itself.
*
* @param object
* An object to test for nullness.
* @return true if the object parameter is the JSONObject.NULL object or
* null.
*/
@Override
public boolean equals(Object object) {
return object == null || object == this;
}
/**
* Get the "null" string value.
*
* @return The string "null".
*/
@Override
public String toString() {
return "null";
}
}
/**
* It is sometimes more convenient and less ambiguous to have a
* <code>NULL</code> object than to use Java's <code>null</code> value.
* <code>JSONObject.NULL.equals(null)</code> returns <code>true</code>.
* <code>JSONObject.NULL.toString()</code> returns <code>"null"</code>.
*/
public static final Object NULL = new Null();
/**
* Construct an empty JSONObject.
*/
public JSONObject() {
super();
}
/**
* Construct a JSONObject from a subset of another JSONObject. An array of
* strings is used to identify the keys that should be copied. Missing keys
* are ignored.
*
* @param jo
* A JSONObject.
* @param names
* An array of strings.
*/
public JSONObject(JSONObject jo, String[] names) {
this();
for (int i = 0; i < names.length; i += 1) {
try {
putOnce(names[i], jo.opt(names[i]));
} catch (Exception ignore) {
}
}
}
/**
* Construct a JSONObject from a JSONTokener.
*
* @param x
* A JSONTokener object containing the source string.
* @throws JSONException
* If there is a syntax error in the source string or a
* duplicated key.
*/
public JSONObject(JSONTokener x) throws JSONException {
this();
char c;
String key;
if (x.nextClean() != '{') {
throw x.syntaxError("A JSONObject text must begin with '{'");
}
for (;;) {
c = x.nextClean();
switch (c) {
case 0:
throw x.syntaxError("A JSONObject text must end with '}'");
case '}':
return;
default:
x.back();
key = x.nextValue().toString();
}
// The key is followed by ':'.
c = x.nextClean();
if (c != ':') {
throw x.syntaxError("Expected a ':' after a key");
}
putOnce(key, x.nextValue());
// Pairs are separated by ','.
switch (x.nextClean()) {
case ';':
case ',':
if (x.nextClean() == '}') {
return;
}
x.back();
break;
case '}':
return;
default:
throw x.syntaxError("Expected a ',' or '}'");
}
}
}
/**
* Construct a JSONObject from a Map.
*
* @param map
* A map object that can be used to initialize the contents of
* the JSONObject.
*/
public JSONObject(Map<?, ?> map) {
this();
if (map != null) {
for (final Entry<?, ?> e : map.entrySet()) {
final Object value = e.getValue();
if (value != null) {
super.put(String.valueOf(e.getKey()), wrap(value));
}
}
}
}
/**
* Construct a JSONObject from an Object using bean getters. It reflects on
* all of the public methods of the object. For each of the methods with no
* parameters and a name starting with <code>"get"</code> or
* <code>"is"</code> followed by an uppercase letter, the method is invoked,
* and a key and the value returned from the getter method are put into the
* new JSONObject.
*
* The key is formed by removing the <code>"get"</code> or <code>"is"</code>
* prefix. If the second remaining character is not upper case, then the
* first character is converted to lower case.
*
* For example, if an object has a method named <code>"getName"</code>, and
* if the result of calling <code>object.getName()</code> is
* <code>"Larry Fine"</code>, then the JSONObject will contain
* <code>"name": "Larry Fine"</code>.
*
* @param bean
* An object that has getter methods that should be used to make
* a JSONObject.
*/
public JSONObject(Object bean) {
this();
populateMap(bean);
}
/**
* 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 {
putOpt(name, c.getField(name).get(object));
} catch (Exception ignore) {
}
}
}
/**
* 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> <small>(left
* brace)</small> and ending with <code>}</code>
* <small>(right brace)</small>.
* @exception JSONException
* If there is a syntax error in the source string or a
* duplicated key.
*/
public JSONObject(String source) throws JSONException {
this(new JSONTokener(source));
}
/**
* Construct a JSONObject from a ResourceBundle.
*
* @param baseName
* The ResourceBundle base name.
* @param locale
* The Locale to load the ResourceBundle for.
* @throws JSONException
* If any JSONExceptions are detected.
*/
public JSONObject(String baseName, Locale locale) throws JSONException {
this();
ResourceBundle bundle = ResourceBundle.getBundle(baseName, locale,
Thread.currentThread().getContextClassLoader());
// Iterate through the keys in the bundle.
Enumeration<String> keys = bundle.getKeys();
while (keys.hasMoreElements()) {
Object key = keys.nextElement();
if (key != null) {
// Go through the path, ensuring that there is a nested JSONObject for each
// segment except the last. Add the value using the last segment's name into
// the deepest nested JSONObject.
String[] path = ((String) key).split("\\.");
int last = path.length - 1;
JSONObject target = this;
for (int i = 0; i < last; i += 1) {
String segment = path[i];
JSONObject nextTarget = target.optJSONObject(segment);
if (nextTarget == null) {
nextTarget = new JSONObject();
target.put(segment, nextTarget);
}
target = nextTarget;
}
target.put(path[last], bundle.getString((String) key));
}
}
}
/**
* 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.
*
* If only one value is accumulated that is not a JSONArray, then the result
* will be the same as using put. But if multiple values are accumulated,
* then the result will be like append.
*
* @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 object = opt(key);
if (object == null) {
put(key, value instanceof JSONArray ? new JSONArray().put(value) : value);
} else if (object instanceof JSONArray) {
((JSONArray) object).put(value);
} else {
this.put(key, new JSONArray().put(object).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 object = opt(key);
if (object == null) {
this.put(key, new JSONArray().put(value));
} else if (object instanceof JSONArray) {
this.put(key, ((JSONArray) object).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.
*/
public static String doubleToString(double d) {
if (Double.isInfinite(d) || Double.isNaN(d)) {
return "null";
}
// Shave off trailing zeros and decimal point, if possible.
String string = Double.toString(d);
if (string.indexOf('.') > 0 && string.indexOf('e') < 0
&& string.indexOf('E') < 0) {
while (string.endsWith("0")) {
string = string.substring(0, string.length() - 1);
}
if (string.endsWith(".")) {
string = string.substring(0, string.length() - 1);
}
}
return string;
}
/**
* 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 {
if (key == null) {
throw new JSONException("Null key.");
}
Object object = opt(key);
if (object == null) {
throw new JSONException("JSONObject[" + quote(key) + "] not found.");
}
return object;
}
/**
* Get the enum value associated with a key.
*
* @param clazz
* The type of enum to retrieve.
* @param key
* A key string.
* @return The enum value associated with the key
* @throws JSONException
* if the key is not found or if the value cannot be converted
* to an enum.
*/
public <E extends Enum<E>> E getEnum(Class<E> clazz, String key) throws JSONException {
E val = optEnum(clazz, key);
if(val==null) {
// JSONException should really take a throwable argument.
// If it did, I would re-implement this with the Enum.valueOf
// method and place any thrown exception in the JSONException
throw new JSONException("JSONObject[" + quote(key)
+ "] is not an enum of type " + quote(clazz.getSimpleName())
+ ".");
}
return val;
}
/**
* 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 object = this.get(key);
if (object.equals(Boolean.FALSE)
|| (object instanceof String && ((String) object)
.equalsIgnoreCase("false"))) {
return false;
} else if (object.equals(Boolean.TRUE)
|| (object instanceof String && ((String) object)
.equalsIgnoreCase("true"))) {
return true;
}
throw new JSONException("JSONObject[" + quote(key)
+ "] is not a Boolean.");
}
/**
* Get the BigInteger 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 cannot
* be converted to BigInteger.
*/
public BigInteger getBigInteger(String key) throws JSONException {
Object object = this.get(key);
try {
return new BigInteger(object.toString());
} catch (Exception e) {
throw new JSONException("JSONObject[" + quote(key)
+ "] could not be converted to BigInteger.");
}
}
/**
* Get the BigDecimal 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
* cannot be converted to BigDecimal.
*/
public BigDecimal getBigDecimal(String key) throws JSONException {
Object object = this.get(key);
try {
return new BigDecimal(object.toString());
} catch (Exception e) {
throw new JSONException("JSONObject[" + quote(key)
+ "] could not be converted to BigDecimal.");
}
}
/**
* 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 object = this.get(key);
try {
return object instanceof Number ? ((Number) object).doubleValue()
: Double.parseDouble((String) object);
} catch (Exception e) {
throw new JSONException("JSONObject[" + quote(key)
+ "] is not a number.");
}
}
/**
* Get the int value associated with a key.
*
* @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 object = this.get(key);
try {
return object instanceof Number ? ((Number) object).intValue()
: Integer.parseInt((String) object);
} catch (Exception e) {
throw new JSONException("JSONObject[" + quote(key)
+ "] is not an int.");
}
}
/**
* 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 object = this.get(key);
if (object instanceof JSONArray) {
return (JSONArray) object;
}
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 object = this.get(key);
if (object instanceof JSONObject) {
return (JSONObject) object;
}
throw new JSONException("JSONObject[" + quote(key)
+ "] is not a JSONObject.");
}
/**
* Get the long value associated with a key.
*
* @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 object = this.get(key);
try {
return object instanceof Number ? ((Number) object).longValue()
: Long.parseLong((String) object);
} catch (Exception e) {
throw new JSONException("JSONObject[" + quote(key)
+ "] is not a long.");
}
}
/**
* 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<String> iterator = jo.keys();
String[] names = new String[length];
int i = 0;
while (iterator.hasNext()) {
names[i] = iterator.next();
i += 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 there is no string value for the key.
*/
public String getString(String key) throws JSONException {
Object object = this.get(key);
if (object instanceof String) {
return (String) object;
}
throw new JSONException("JSONObject[" + quote(key) + "] not a string.");
}
/**
* 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 containsKey(key);
}
/**
* Increment a property of a JSONObject. If there is no such property,
* create one with a value of 1. If there is such a property, and if it is
* an Integer, Long, Double, or Float, then add one to it.
*
* @param key
* A key string.
* @return this.
* @throws JSONException
* If there is already a property with this name that is not an
* Integer, Long, Double, or Float.
*/
public JSONObject increment(String key) throws JSONException {
Object value = opt(key);
if (value == null) {
this.put(key, 1);
} else if (value instanceof BigInteger) {
this.put(key, ((BigInteger)value).add(BigInteger.ONE));
} else if (value instanceof BigDecimal) {
this.put(key, ((BigDecimal)value).add(BigDecimal.ONE));
} else if (value instanceof Integer) {
this.put(key, (Integer) value + 1);
} else if (value instanceof Long) {
this.put(key, (Long) value + 1);
} else if (value instanceof Double) {
this.put(key, (Double) value + 1);
} else if (value instanceof Float) {
this.put(key, (Float) value + 1);
} else {
throw new JSONException("Unable to increment [" + quote(key) + "].");
}
return this;
}
/**
* 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<String> keys() {
return keySet().iterator();
}
/**
* Get the number of keys stored in the JSONObject.
*
* @return The number of keys in the JSONObject.
*/
public int length() {
return super.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<String> keys = keys();
while (keys.hasNext()) {
ja.put(keys.next());
}
return ja.length() == 0 ? null : ja;
}
/**
* Produce a string from a Number.
*
* @param number
* A Number
* @return A String.
* @throws JSONException
* If n is a non-finite number.
*/
public static String numberToString(Number number) throws JSONException {
if (number == null) {
throw new JSONException("Null pointer");
}
testValidity(number);
// Shave off trailing zeros and decimal point, if possible.
String string = number.toString();
if (string.indexOf('.') > 0 && string.indexOf('e') < 0
&& string.indexOf('E') < 0) {
while (string.endsWith("0")) {
string = string.substring(0, string.length() - 1);
}
if (string.endsWith(".")) {
string = string.substring(0, string.length() - 1);
}
}
return string;
}
/**
* Get an optional value associated with a key.
*
* @param key
* A key string.
* @return An object which is the value, or null if there is no value.
*/
public Object opt(String key) {
return key == null ? null : super.get(key);
}
/**
* Get the enum value associated with a key.
*
* @param clazz
* The type of enum to retrieve.
* @param key
* A key string.
* @return The enum value associated with the key or null if not found
*/
public <E extends Enum<E>> E optEnum(Class<E> clazz, String key) {
return this.optEnum(clazz, key, null);
}
/**
* Get the enum value associated with a key.
*
* @param clazz
* The type of enum to retrieve.
* @param key
* A key string.
* @param defaultValue
* The default in case the value is not found
* @return The enum value associated with the key or defaultValue
* if the value is not found or cannot be assigned to clazz
*/
public <E extends Enum<E>> E optEnum(Class<E> clazz, String key, E defaultValue) {
try {
Object val = opt(key);
if (NULL.equals(val)) {
return defaultValue;
}
if (clazz.isAssignableFrom(val.getClass())) {
// we just checked it!
@SuppressWarnings("unchecked")
E myE = (E) val;
return myE;
}
return Enum.valueOf(clazz, val.toString());
} catch (IllegalArgumentException | NullPointerException e) {
return defaultValue;
}
}
/**
* Get an optional boolean associated with a key. It returns false if there
* is no such key, or if the value is not Boolean.TRUE or the String "true".
*
* @param key
* A key string.
* @return The truth.
*/
public boolean optBoolean(String key) {
return this.optBoolean(key, false);
}
/**
* Get an optional boolean associated with a key. It returns the
* defaultValue if there is no such key, or if it is not a Boolean or the
* String "true" or "false" (case insensitive).
*
* @param key
* A key string.
* @param defaultValue
* The default.
* @return The truth.
*/
public boolean optBoolean(String key, boolean defaultValue) {
try {
return getBoolean(key);
} catch (Exception e) {
return defaultValue;
}
}
/**
* Get an optional double associated with a key, or NaN if there is no such
* key or if its value is not a number. If the value is a string, an attempt
* will be made to evaluate it as a number.
*
* @param key
* A string which is the key.
* @return An object which is the value.
*/
public double optDouble(String key) {
return this.optDouble(key, Double.NaN);
}
/**
* Get an optional BigInteger associated with a key, or the defaultValue if
* there is no such key or if its value is not a number. If the value is a
* string, an attempt will be made to evaluate it as a number.
*
* @param key
* A key string.
* @param defaultValue
* The default.
* @return An object which is the value.
*/
public BigInteger optBigInteger(String key, BigInteger defaultValue) {
try {
return getBigInteger(key);
} catch (Exception e) {
return defaultValue;
}
}
/**
* Get an optional BigDecimal associated with a key, or the defaultValue if
* there is no such key or if its value is not a number. If the value is a
* string, an attempt will be made to evaluate it as a number.
*
* @param key
* A key string.
* @param defaultValue
* The default.
* @return An object which is the value.
*/
public BigDecimal optBigDecimal(String key, BigDecimal defaultValue) {
try {
return getBigDecimal(key);
} catch (Exception e) {
return defaultValue;
}
}
/**
* Get an optional double associated with a key, or the defaultValue if
* there is no such key or if its value is not a number. If the value is a
* string, an attempt will be made to evaluate it as a number.
*
* @param key
* A key string.
* @param defaultValue
* The default.
* @return An object which is the value.
*/
public double optDouble(String key, double defaultValue) {
try {
return getDouble(key);
} catch (Exception e) {
return defaultValue;
}
}
/**
* Get an optional int value associated with a key, or zero if there is no
* such key or if the value is not a number. If the value is a string, an
* attempt will be made to evaluate it as a number.
*
* @param key
* A key string.
* @return An object which is the value.