The accepted answer by Francisco Spaeth works and is easy to follow. However, I think that method of building JSON sucks! This was really driven home for me as I converted some Python to Java where I could use dictionaries and nested lists, etc. to build JSON with ridiculously greater ease.
What I really don't like is having to instantiate separate objects (and generally even name them) to build up these nestings. If you have a lot of objects or data to deal with, or your use is more abstract, that is a real pain!
I tried getting around some of that by attempting to clear and reuse temp json objects and lists, but that didn't work for me because all the puts and gets, etc. in these Java objects work by reference not value. So, I'd end up with JSON objects containing a bunch of screwy data after still having some ugly (albeit differently styled) code.
So, here's what I came up with to clean this up. It could use further development, but this should help serve as a base for those of you looking for more reasonable JSON building code:
import java.util.AbstractMap.SimpleEntry;
import java.util.ArrayList;
import java.util.List;
import org.json.simple.JSONObject;
// create and initialize an object
public static JSONObject buildObject( final SimpleEntry... entries ) {
JSONObject object = new JSONObject();
for( SimpleEntry e : entries ) object.put( e.getKey(), e.getValue() );
return object;
}
// nest a list of objects inside another
public static void putObjects( final JSONObject parentObject, final String key,
final JSONObject... objects ) {
List objectList = new ArrayList<JSONObject>();
for( JSONObject o : objects ) objectList.add( o );
parentObject.put( key, objectList );
}
Implementation example:
JSONObject jsonRequest = new JSONObject();
putObjects( jsonRequest, "parent1Key",
buildObject(
new SimpleEntry( "child1Key1", "someValue" )
, new SimpleEntry( "child1Key2", "someValue" )
)
, buildObject(
new SimpleEntry( "child2Key1", "someValue" )
, new SimpleEntry( "child2Key2", "someValue" )
)
);