How to extract array from json object in java. List<String> locations = JsonPath.

How to extract array from json object in java JSONArray jsonMainArr = jsonRes. So, you could do this: response. JSONArray. I don't know how to specify that "attribute" is an JSONArray and not a JSONObject or how to set the proper path to it. Iterating over JSON array in Java have To Accept it first as a Json Array ,then while reading its Object have to use Object Mapper. Let's say you have this json in java. To get keys from all levels, you can create a recusive function which when the value of the key is another HashMap you extract it again. Feb 25, 2014 · item is a JSON array with a single element, another JSON object. – Jun 7, 2017 · Ask questions, find answers and collaborate at work with Stack Overflow for Teams. Note that we should know the JSON Object structure that we are iterating because we need to extract the values in a JSON Object using the key. @JsonIgnoreProperties(ignoreUnknown = true) public class Rate { private String name; private String code; private Double rate; // add getters and setters } Please note, that the return value of jsonPath is an array, which is also a valid JSON structure. simple is yet another similar and powerful alternative for working with JSON in Java. And did not get the original byte array even I use following: byte[] bArray=jSONObject. Aug 25, 2011 · I have JSONObject like this: {"status":[{"Response":"success"}]}. , [{ "id": 1002, "ent Nov 13, 2017 · I’ve a simple question, and was wondering if someone here could help me how to parse through a Json string and extract all the User and put it into a List? Note the object key directly under Users is a random number which can change with every response! Jan 9, 2015 · Here in this resArr, I am mapping it to initialArr[ ], to generate an array out of it called resArr and the each element initialArr is represented as 'x' in this x is an object now inorde to get the 2nd element of the object x[1] so here, 1 represents the second element as index starts from 0,1 ,,,so we need to get the keys of that object by Feb 6, 2018 · This is how to get the json string as a json object: ObjectMapper mapper = new ObjectMapper(); //using jackson JsonNode root = mapper. I have an API whose response is JSONArray i. IOException; import com Aug 25, 2015 · Iteration cannot be avoided here as org. Try Teams for free Explore Teams Oct 12, 2019 · How to extract json Objects from String Builder? JSONArray array = new JSONArray(sb. to extract the array, sample java Array items within the other objects might start data element holds nested array. Example, From issues, key:651, From project name:test, updated, created This details for all records of array issues. length. jar. This is useful when we want to extract only those array items that match a certain criterion. Jun 18, 2014 · You did not specify which library you intend to use to represent the JSON object. Mar 5, 2024 · How to extract value from JSON array with javax. Oct 5, 2013 · I'm trying to extract the keys from a JSON Object. As JSONObject notation is represented by braces i. Dec 12, 2020 · I am learning java8 functional programming and I am going through Optional Lambdas. Mar 30, 2016 · Using a set of non-capturing group you can extract a predefined json array. In JavaScript, there are two ways to access objects. Can anyone please help me to solve this scenario: I am new to RestAssured and handling JSON in our automation script. getJSONArray("data"); you can get its first (and only) inner array [3] with . Once you run a JSON string through JSON. You will, unfortunately, find about 20 different ways to do it, most of which are too complicated, but the Java gurus seem to like it that way. length); array. class); My List class is:- Get IMDB data to JSON array in java. By following these steps, you can easily convert a JSON array to a Java array and work with the data in your Java application. sql. json&quot;)); Jun 23, 2022 · For more complicated use cases, if you'd like to define your own class, and want to deserialize JSON string to your class, then you can use Gson or Jackson: // Create your own class: /* public class YourOwnClass { private List<String> firstNames; public List<String> getFirstNames() { return firstNames; } } */ Gson gson = new Gson(); YourOwnClass customObject1 = gson. readValue(jsonString, StudentList. For Ex: Make class POJO: Extracting data from JSON array. How to set variables consumed from a JSON in strings. Here's how you can fix it: Apr 22, 2019 · I want to extract below json and use values accordingly. Java - How to get object value in JSON array? 0. We can use the fromJson() method in the usual manner and it will parse the JSON array correctly to the required java array or list. operator like normal JAVA Object. How to retrieve json array elements from JSON object in Java? Hot Network Questions Oct 30, 2014 · I added byte array value previously on JSONObject and stored as String. String s = "YOUR_URL_HERE"; URL url = new URL(s); Scanner scan = new Scanner(url. it begins with ‘[’ and ends with ‘]’. Jan 10, 2013 · I have the following lines of Java code: Object[] results = api. The following is what I have tried and it didn't work: $. JSONParser parser = new JSONParser(); Object Obj = parser. e. Object) and that it will interface with that class in a specific way, albeit normally it will call for an interface instead (hence the name) OR it can accept I have this in my String object. Currently you are using getJSONArray, but arrays in JSON have [array, array], or square brackets, where JSON objects have {object, object} curly braces. <dependency> <groupId>com. When I tried to get from JSONObject to my byte array it returned String not my original byte array. I just need very few fields from the JSON. Gson parses JSON arrays as members without difficulty if they are non-root objects. Please guide me as to where I'm making the mistake and how to rectify this. See the dot? Apr 18, 2012 · With the json. I/p JSON:- Jmeter : How to extract first element from json array. JSONArray jsonArray = (JSONArray) JSONSerializer. Hot Network Questions May 31, 2013 · I have a string in json format and I want to extract certain values from that json. from bossresponse object you will have web object from web you will have results object. Steps to Convert an ArrayList of Objects to a JSON Array in Java Jan 13, 2021 · I like to use google-gson for this, and it's precisely because I don't need to work with JSONObject directly. However, it throws a NullPointerException on this line: Iterator<String> iterator = email_domains. Sample JSON array{ books: [ Java, JavaFX, Hbase, Cassandra, WebGL, JOGL] }The json-simple is a ligh Oct 4, 2014 · @Gangnus I'm however glad I could help and wish you peace! Thanks for contributing to the creation of some more information: I think you'll appreciate the starting point I set up in my answer, and I would be more than happy to explore new tools that have been made available since then if you were to require further assistance in the form of a new question of your own. String json = "{\"price\" : \"554. . Here’s a simple example using the org. TYPE ); int[] output = (int[]) JSONSerializer. Further, we extract the data from the JSON Object by passing it to a function that uses named keys. Sample JSON Data: Jan 9, 2014 · Ask questions, find answers and collaborate at work with Stack Overflow for Teams. jsonschema2pojo. The dot notation goes like this. How to read parse JSON array using Java - A Json array is an ordered collection of values that are enclosed in square brackets i. JSONObject. That JSON object contains a value named name. This can be tricky because it depends from library you want to use to serialise/deserialise Oct 31, 2015 · for anyone looking at this in the future, using json_simple-1. simple library to access this feature through Java means we can encode or decode JSON Object using this json. 520020\"}"; Then price needs to be Double or double. Aug 18, 2017 · I know its an array, but I am completely new to JSON and need help comprehending how this is structured, here is my attempt at extracting data: String JSonString = readURL("//my URL is here"); JSO Aug 7, 2019 · Json-Simple API : It provides object models for JSON object and array structures. As a simplified example, I want to extract only file01, and I need the json object as a string. The same goes if you have nested arrays, or other objects. Java in your case. Since you already have this array in . 1. I just want to print the Systout(Objects) in the for loop as above format. getDouble("lat"); Mar 8, 2017 · I always need to extract an array of any kind of object from a list, let me explain with code: This is my list: List<myObj> myList = new ArrayList<myObj>;(); My object has 2 objects, Aug 22, 2022 · Predicates help in filtering an array of nodes based on provided condition(s). keys() returns an iterator of the String names in the object. getString(key). A JSON object is delimited by "{" and "}" and represent a single object/structure inside a . 1. Getting the string value from a JSON array's object in Java. In that case I'd have a class that will correspond to the properties of your JSON Object Nov 2, 2015 · Extract a part of the JSON object in JAVA. getProjects(); for(int i=0; i&lt;results. The JSON object, in this case, is obtained by making an API call to a social networking site called SkyRock and looks like this : { "max_page": 1. Map; import org. openStream Mar 11, 2019 · I have JSON data and want to extract data of only specific fields in Java and store it in String. 2 Oct 19, 2016 · I got an JSON Array for my Twitch Following user checker. May 3, 2019 · Extracting an array from a JSON object. Now, the json. 3. So basically it will always return an array. Jun 17, 2014 · So you have the JsonArray object with your records, here's what you do to get your functional objects: Type type = new TypeToken<List<DataMetrics>>() {}. Jan 17, 2018 · Whats the best way to extract an internal Json array to a Java list using Jackson (without converting the whole Json Structure). Select annotation style. fromJson(jsonString Jul 6, 2021 · // In order to read the returned json, first build an ObjectMapper ObjectMapper mapper = new ObjectMapper(); // For your comments, you are using the class SecondClass SecondClass secondClass = mapper. java:539) at Mar 26, 2013 · You've got an array containing an object containing an array. How to extract array values within nested JSON data. It implements the List interface and is the most commonly used implementation of List. import java. fromJson(); Now remember that you need right properties for the job. 61}, and converts it into a Double. Jan 8, 2024 · Here, we have used JSON-Java (org. Extract JSON value using Jmeter. You can do it with get(0), or to get more precise return type getInt(0). You first need to index the array, then extract element "fingerprint" from the resulting object. So to access we first have to install json. I have the following JSON structure and I would like to extract the 3 from the value from context containing All UpdateCounter's. MODE_OBJECT_ARRAY ); jsonConfig. getJSONObject("location"); double lng = location. To check the number of elements in a JSON object, you can use JSONObject. I am using below code to convert it into List of Java object : - ObjectMapper mapper = new ObjectMapper(); StudentList studentList = mapper. getJSONArray("from_excel"); then iterate the array and get each jsonobject. toString(). We have already seen the inline predicate example in the previous section. name. Feb 17, 2020 · The above request may have "n" number of array[n]. – Jan 21, 2013 · This will solve the problem: const json_data = {"2013-01-21":1,"2013-01-22":7}; const arr = Object. json library: Apr 27, 2014 · When you create the JSON string , don't append the index. In general I will have more than 500 objects. getJSONObject(i). What you actually want to do, is to return the given jsonArray for any call to someService. display == 'true Java Program to print the largest element in an array; Java Program to print the smallest element in an array; Java Program to print the number of elements present in an array; Java Program to print the sum of all the items of the array; Java Program to right rotate the elements of an array; Java Program to sort the elements of an array in Sep 17, 2015 · Stack Overflow for Teams Where developers & technologists share private knowledge with coworkers; Advertising & Talent Reach devs & technologists worldwide about your product, service or employer brand If that was the case, look at the following snippet to convert json array to java array. 0. io. Related. But it's all I have and have to go with it. If you use Double you To extract a Java List, and not an Array, Your json path can point to anywhere you expect to have a list of json objects in your body. keys(json_data). Here is a portion of the code that I'm using to extract the array of values associated with "heart": Jun 9, 2018 · count property itself is not an array in your JSON so array notation on count such as count[0] doesn't work. Converting json Sep 24, 2013 · The other things to keep in mind is that you have a nested object, which holds the lat and long, so you have to get that, then parse that. The other versions simply remove the explicit looping. Retrieve just one field from JSON string in Java. But the expression $. So you should achieve it is array. println(results[i]. Or consider using a different JSON parsing library like Jackson or Gson that mostly does this for you based on some POJO class. It makes response handling very simple. util. This should work fine for you Two of the sample JSON responses are of this structure, one returns an array of objects where the other returns a series of properties. e {} Nov 15, 2018 · Stack Overflow for Teams Where developers & technologists share private knowledge with coworkers; Advertising & Talent Reach devs & technologists worldwide about your product, service or employer brand May 16, 2015 · In this code to get "email_domains" only, a JSON Array object is created that get data from the JSON object and then its iterator is used to get values from within the array. *; impor The string that you get is just the JSON Object. length; var random = Math. { "files":[ { "name":"/testi Oct 1, 2015 · as your new to Java and JSON is one of the most famous data interchange language out there, I recommend you to understand the parsing and the structure of JSON thoroughly this example. Array; import java. Table of Content Using the forEach() methodUsing the map() methodUsing the filte I've never used this, nor have I tested it, but looking at your code and the documentation for JSONObject and JSONArray, this is what I suggest. If I do it in the traditional way I would have to create many classes. Using Simple json library to read the JSONObject. Extracting an array from a JSON object Feb 21, 2012 · JSON extract values from key. Nov 25, 2010 · Thank you, My last Question is for example object1 is my jsonobject can i convert this json object directly to string type means String jsonstr= object1; but you have taken a class which have the data belongs to json object In my project i am getting this data dynamically means data may change day by day. The code inside your setLongitude tries to retrieve the element at position 1, which is null. Jan 20, 2025 · Here’s a detailed look at how to effectively retrieve values from JSON objects in Java. Mar 16, 2018 · The body() method accepts a path and a Hamcrest matcher (see the javadocs). e. ) Create a JSONObject while passing your string to JSONObject constructor as input. Mar 10, 2018 · What is a JSON object : (just to be clear) A . I know how to iterate over JSONArrays, but when I parse JSON data from Facebook I don't get an array, only a JSONObject, but I need to be able to access an item via its index, such as JSONObject[0] to get the first one, and I can't figure out how to do it. It means that you get the JSON object, but in a String format. Oct 21, 2016 · Random(). json. Please feel free to explore. widget. jsonMainArr. fromJson(jsonArrayThatYouHave, type); The [] in JSON represents an array and should map to a Java collection such as List or just a plain Java array. Author var bookAuthorLink = randomBook. json file. So, you can't query something like "all name properties of all contact objects" unless you probably get a Json parser like Gson to unmarshall it that way. converting JSON OBJECT to JSON ARRAY. When an array contains objects, it is called an array of objects. I would like to get only the first date (cause thats the newest one) out of the array but everytime my code gets executed it just swap to the Feb 12, 2015 · Of course, I can deserialize the string to a Java array of objects and then serialize each object to string, but that is not safe because the final output might no longer be be byte-for-byte exact the input (which is a requirement. JSON. Mar 7, 2020 · In your code, you define that when the specific instance of jsonObject is encountered, the mocked someservice should return the jsonArray. e String. – Jul 23, 2019 · I know that question is about JSONArray but here's example I've found useful where you don't need to use JSONArray to extract objects from JSONObject. You need to perform the function on the existing array: Random(). toJSON( input ); JsonConfig jsonConfig = new JsonConfig(); jsonConfig. In your JSON object, which is actually a composite object, the main object consists o two sub-objects. I am not sure how the for loop would work to add my elements from jsonArray into myJSONArray (arrayList) Oct 2, 2019 · I am trying to get the current status of a flight from a 3rd party API. in this example (and Nov 18, 2022 · I want my Java program to create a structure of two objects of class User, each of it holding the corresponding fields. Apr 6, 2016 · org. I don't know how to extract a particular entry from within a json array. So, our POJO classes should have the same hierarchy. Now I want to convert it into Java object and store it in List of java object. JSONException: JSONArray initial value should be a string or collection or array. myObject. window. Improve this question. The "fingerprint" element will be an array which is presumably the byte array you want. They don't buy you that much snce this isn't a lazy problem; you need to compute the entire thing. JSON in your case. Oct 7, 2015 · How to extract an array of JSON inside JSON array. length(). now you are kind a reading results from first level. results. display == 'true May 17, 2024 · Use Gson to deserialize the JSON array into an array of Java objects of that class. Also change the outer {(curly brace) to [ (square bracket) to represent as Array element. nextInt(jsonArray) to get a random number other than zero. json) library. These JSON structures are represented as object models using types JSONObject and JSONArray. Aug 31, 2016 · It maps your JSON reponse in respective class objects. read(json, "$. 2. g. getBytes(); Now, Jan 30, 2015 · So I have this much code to start off (I included the import because I thought you might want to see what I imported): import java. In this case, each JSON object within 'result' should be deserialized into it's own POJO instance. body("$", customMatcher); For example Sep 3, 2014 · I have a below JSON document which I need to parse. getType(); List<DataMetrics> records = gson. In Student object. For a single object I would do this: The complete example with an array. googlecode. log(arr); Sep 26, 2017 · var n = json. I am showing only two objects in files array. at org. org. How to extract specific fields of JSON Array in Java and store Jul 31, 2013 · That's because the JRE is doing the same thing. JSONObject : It's a type representing a single JSON object in JAVA. Since JSON Object Feb 2, 2023 · Here is a simple Java tutorial which demonstrate how to parse JSONObject and JSONArrays in Java. As usual, the complete source code is available over on Github. You can add getter setter for that response model objects. counters. setArrayMode( JsonConfig. Apr 10, 2014 · This reads as "coordinates contains an array of location objects" which indicates a better JSON structure. Mar 21, 2015 · First define an object to hold the entity coming back in the array. out. I made an iPhone app using this json, now I need to do it for Android and cannot figure it out. length is the new array you just created. Object class, more than likely it's really telling you that you're expected to create your own class (since all Classes ultimately extend java. getJSONArray(0) Now you need to get its only element. iterator(); I am stuck due to this problem. Extracting data from JSON array. java Nov 8, 2017 · Stack Overflow for Teams Where developers & technologists share private knowledge with coworkers; Advertising & Talent Reach devs & technologists worldwide about your product, service or employer brand Apr 29, 2013 · I have a JSON Object of the following and I need to parse the path strings inside the web array into an new JSON array. json-simple</groupId> <artifactId>json-simple</artifactId> </dependency> Can anyone help me to achieve this? Jul 26, 2011 · Still working on this part of my script to parse my JSON jsonArray = new JSONArray(jsonData); and then adding it to a arraylist "myJSONArray" . Aug 12, 2018 · Stack Overflow for Teams Where developers & technologists share private knowledge with coworkers; Advertising & Talent Reach devs & technologists worldwide about your product, service or employer brand Aug 29, 2018 · I need to get a json string, that is part of a larger json. I guess It would work if json is { results:[ { //here attrs } ] } Sep 24, 2013 · I know how to parse it if the JSON was written differently (In other words, if I had json object returned instead of an array of objects). Aug 22, 2022 · Predicates help in filtering an array of nodes based on provided condition(s). Select source. You have a JSON object with several properties of which the groups property represents an array of nested objects of the very same type Dec 2, 2024 · In JavaScript, an array is a data structure that can hold a collection of values, which can be of any data type, including numbers, strings, and objects. ) Create an arraylist of appropriate type, in this case i. I managed to do it with only one value mentioned in the file (so no JSON array, just an object between {} and some key-value pairs), but with a list it gets more Oct 26, 2020 · The code inside your setLatitude gets the element at position 0 in your array, which is {"lat":35. JSONObject jsonObject = (JSONObject) obj; JSONArray array = obj. getString("solution"); } Mar 19, 2019 · In case you need generate POJO model based on JSON or JSON Schema use www. Replace "constructArrayType()" by "constructCollectionType()" or any other type you need. Example print screen shows how to use it: How to use it: Select target language. for(int i = 0 ; i < array. So you might want to apply jsonPath to the resulting structure again or use one of your favorite array methods as sort with it. solved the issue of parsing a json String into a java object. Are you checking if the array has 4 object components, or if an object in the array has 4 elements? To check the number of object components in the array, use getArray. For example: org. all. Access the elements of the Java array and perform any necessary operations. May 23, 2015 · If you don't know if it is a array or object create different classes to handle it for you. lang. map((key) => [key, json_data[key]]); console. Dot Notation. Follow how to parse json object inside json object in java. readValue ,because Json Object Still in String . readTree(json); //TODO how loop all nodes and subnodes, and always get their key + value? But how can I now iterate through all nodes and extract their key and content? I'm recieving JSON from the Google Directions API and the request is like the one shown here (under Directions Responses -> Json Output) link. it is not possible to write this type of It should have bossresponse attribut, and it is another object. 65, "lng":139. json and other Json parsers as well provide random access to objects but not to their properties collectively (as a collection). I believe your are reading the data from sqlite and generating the JSON string. Jul 19, 2017 · i want to get the array of json objects from a json object. java; json; Share. Sep 26, 2016 · from_excel is JSON array not an object. The {} in JSON represents an object and should map to a Java Map or just some JavaBean class. 13. Usually there are methods to enumerate the properties of the object. Access multiple json objects in java. // Receive JSON from server and parse it. bossresponse->web->results. length() ; i++){ array. getJsonArray and the second parameter being "educations". nextInt(array. So your json string will be like this May 27, 2016 · How to fetch JSON object from Json array in REST API. 3) Cast the parse result to the Java object that was created from the initial JSON schema. The values in the arrays are separated by ‘,’ (comma). locations[?(@. Explore Teams I use a JSON library called JSONObject (I don't mind switching if I need to). You need to get that JSON object so that you can retrieve that value. Something like the below. simple package for Java contains the following files in it. 2) Use JSON parser libraries to avoid any sort of exception . In this article, we will learn how to convert an ArrayList of objects to a JSON array in Java. payments[?(@. If I want to convert the JSONObject value, which is a JSONArray into JSONObject automatically without using any static value, here is the code for that. Java program to deserialize JSON array as member object – to Java array of objects as Feb 2, 2024 · We extract each JSON Object from the parsed JSON Array and further process it. If you are supposed to get a JSON Object you can just put: JSONObject myObject = new JSONObject(result); Apr 3, 2013 · I just missing the part how I can convert the Java object to JSON with Jackson: Parsing the nested JSON Array using Jackson library in java. *EDIT: It is a valid json. Parsing a JSON Array Jul 25, 2016 · I have tried different approaches (json, gson, jayway-JsonPath) but I don't manage to get the values from the "attribute" array, only those from the first array. parse(new FileReader(&quot;demoprgmsv1. Below is an example JSON Schema" Feb 4, 2017 · Get the last object from a JSONArray in android kotlin How to extract last item in Json Array without parsing the entire Json message. Just parse the data with new Gson(). readValue(json, SecondClass. getJSONArray(JSONObject. toJava Jackson is going to traverse the methods (using reflection), and maps the JSON object into the POJO instance as the field names of the class fits to the field names of the JSON object. Android: converting JSONObject to JSONArray returns null. Accessing JSON Values in Java. JSON syntax is a subset of the JavaScript object notation Nov 26, 2022 · Here we simply use the json. Ask Question ["ProjectID"] is not a JSONArray. count when evaluated returns a Java list so to get the first count we can just get the first element from the list: Try looking for info on how to parse JSON in Java -- to convert the JSON (in your case) into a Map. json file contains text-based representations of data structures and objects. getDouble("lng"); double lat = location. parse, it is a native JavaScript object. simple package. Sort array of objects by string property value How do I determine whether an array contains a particular Feb 14, 2024 · In Java, an ArrayList is a resizable array implementation of the List interface. List<String> locations = JsonPath. floor((Math. xml. getNames(objects). Author_link Mar 30, 2017 · How do I convert my Response into a JSON object and then extract a field that is within the JSON array (in my case, inside the errors array)? Response response = given(). Book var bookAuthor = randomBook. toString()); How to get Java objects from JSON string. name == 'yesterday')]. class); //If instead, you are returning a list of objects, for example, try this: // SecondClass[] secondClasses Apr 8, 2020 · What I'm attempting to do is extract one of the three arrays found within that JSON object, but I'm receiving a JSONException: Not a primitive array: class org. simple library in Java Programming Language. JSONObject provides a Map view to access the unordered collection of zero or more name/value pairs from the model. random() * n); To reference an item in your json data, you can use array and dictionary references. Extract a part of the Dec 13, 2016 · Make pojo of each Json Object in your Json String. setRootClass( Integer. The method asDouble on a null object causes the NullPointerException. to extract as in flat json? I was passing an array. JSON). Lets say I have the Json: It helps if you don't think of JSON objects as JSON objects. toString()); } An 1) Create the Java Beans from the JSON schema . then(). contentType(ContentType. As for ensuring you don't get a certain age, I'd suggest breaking up the code to not call the getRandomCow(array) function inside of the for loop. org library for Java, you can only get at the individual properties of an object by first getting the parent JSONObject instance: JSONObject object = new JSONObject(json); JSONObject location = object. assertThat(). Oct 31, 2014 · The Jackson data binding documentation indicates that Jackson supports deserialising "Arrays of all supported types" but I can't figure out the exact syntax for this. length; i++){ System. simple. var randomBook = json[random]; var bookTitle = randomBook. And, map th Dec 20, 2019 · You can use Jackson to parse to an HashMap<String, Object> and then get the keys of your HashMap (if you intend to get all keys of the first level of course). Mar 21, 2015 · When a constructor calls for a java. Member JSON Array to Java Array. Extracting an array from a JSON Jan 3, 2014 · JSON-Java can be found on GitHub, How can I extract the array of hashmap object from a hashmap object? 1. And then you can access these JSON values/parameter using . To retrieve a value from a JSON object, you first need to parse the JSON string into a JSON object. nbq jvqyn xgnqk ihxwltnc eilmfth vqlz xqixzc grgbri fqyyjsvyf tvu ycfxvtg omrrxcu iwwerm xseoft lpk