/**
* 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;
}
/**
* Write the contents of the JSONObject as JSON text to a writer. For compactness, no whitespace
* is added.
*
* <p>Warning: This method assumes that the data structure is acyclical.
*
* @return The writer.
* @throws JSONException
*/
public Writer write(Writer writer) throws JSONException {
try {
boolean b = false;
Iterator keys = keys();
writer.write('{');
while (keys.hasNext()) {
if (b) {
writer.write(',');
}
Object k = keys.next();
writer.write(quote(k.toString()));
writer.write(':');
Object v = this.map.get(k);
if (v instanceof JSONObject) {
((JSONObject) v).write(writer);
} else if (v instanceof JSONArray) {
((JSONArray) v).write(writer);
} else {
writer.write(valueToString(v));
}
b = true;
}
writer.write('}');
return writer;
} catch (IOException e) {
throw new JSONException(e);
}
}
/**
* 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.
* @exception JSONException If a value is a non-finite number or if a name is duplicated.
*/
public JSONObject(JSONObject jo, String[] names) throws JSONException {
this();
for (int i = 0; i < names.length; i += 1) {
putOnce(names[i], jo.opt(names[i]));
}
}