Format JSON with org.json

Use org.json.JSONObject.toString (int indentFactor).

package hello.json;

import org.json.JSONArray;
import org.json.JSONObject;

public class HelloOrgJson {

	public static void main(String[] args) {
		JSONObject json = new JSONObject();
		json.put("key1", "value1");
		json.put("key2", "value2");

		String[] ss = { "a", "b", "c" };

		JSONArray arr = new JSONArray();
		for (String s : ss) {
			JSONObject o = new JSONObject();
			o.put("xx", s);
			arr.put(o);
		}
		json.put("arr", arr);

		System.err.println("--- no formatting ---");
		System.err.println(json.toString());
		System.err.println("--- pretty printed ---");
		System.err.println(json.toString(1));
	}

}

result

--- no formatting ---
{"key1":"value1","arr":[{"xx":"a"},{"xx":"b"},{"xx":"c"}],"key2":"value2"}
--- pretty printed ---
{
 "key1": "value1",
 "arr": [
  {"xx": "a"},
  {"xx": "b"},
  {"xx": "c"}
 ],
 "key2": "value2"
}