Merge (Concat) Multiple JSONObjects in Java
In some cases you need a deep merge, i.e., merge the contents of fields with identical names (just like when copying folders in Windows). This function may be helpful:
/**
* Merge "source" into "target". If fields have equal name, merge them recursively.
* @return the merged object (target).
*/
public static JSONObject deepMerge(JSONObject source, JSONObject target) throws JSONException {
for (String key: JSONObject.getNames(source)) {
Object value = source.get(key);
if (!target.has(key)) {
// new value for "key":
target.put(key, value);
} else {
// existing value for "key" - recursively deep merge:
if (value instanceof JSONObject) {
JSONObject valueJson = (JSONObject)value;
deepMerge(valueJson, target.getJSONObject(key));
} else {
target.put(key, value);
}
}
}
return target;
}
/**
* demo program
*/
public static void main(String[] args) throws JSONException {
JSONObject a = new JSONObject("{offer: {issue1: value1}, accept: true}");
JSONObject b = new JSONObject("{offer: {issue2: value2}, reject: false}");
System.out.println(a+ " + " + b+" = "+JsonUtils.deepMerge(a,b));
// prints:
// {"accept":true,"offer":{"issue1":"value1"}} + {"reject":false,"offer":{"issue2":"value2"}} = {"reject":false,"accept":true,"offer":{"issue1":"value1","issue2":"value2"}}
}
If you want a new object with two keys, Object1 and Object2, you can do:
JSONObject Obj1 = (JSONObject) jso1.get("Object1");
JSONObject Obj2 = (JSONObject) jso2.get("Object2");
JSONObject combined = new JSONObject();
combined.put("Object1", Obj1);
combined.put("Object2", Obj2);
If you want to merge them, so e.g. a top level object has 5 keys (Stringkey1, ArrayKey, StringKey2, StringKey3, StringKey4), I think you have to do that manually:
JSONObject merged = new JSONObject(Obj1, JSONObject.getNames(Obj1));
for(String key : JSONObject.getNames(Obj2))
{
merged.put(key, Obj2.get(key));
}
This would be a lot easier if JSONObject implemented Map, and supported putAll.