‘Iterator’ is an interface which belongs to collection framework. It allows us to traverse the collection, access the data element and remove the data elements of the collection.
java.util package has public interface Iterator and contains three methods:
boolean hasNext(): It returns true if Iterator has more element to iterate.
Object next(): It returns the next element in the collection until the hasNext()method return true. This method throws ‘NoSuchElementException’ if there is no next element.
void remove(): It removes from the underlying collection the last element returned by this iterator (optional operation). This method can be called only once per call to next(). The behavior of an iterator is unspecified if the underlying collection is modified while the iteration is in progress in any way other than by calling this method.
forEachRemaining– Performs the given action for each remaining element until all elements have been processed or the action throws an exception. Actions are performed in the order of iteration, if that order is specified. Exceptions thrown by the action are relayed to the caller.
Below is an example of use of Iterator. The iterator() method is used to get an iterator for any collection:
public class IteratorDemo {
public static void main(String[] args) {
ArrayList<String> cars = new ArrayList<String>();
cars.add("Audi");
cars.add("BMW");
cars.add("Ford");
cars.add("Duster");
// Get the iterator
Iterator<String> it = cars.iterator();
// Print the first item
System.out.println("First element from list :"+it.next());
}
}
Output
First element from list :Audi
Looping through Collection
In the below example, we are looping through the collection using hasNext() and next() methods of Iterator.
public class IteratorDemo {
public static void main(String[] args) {
ArrayList<String> cars = new ArrayList<String>();
cars.add("Audi");
cars.add("BMW");
cars.add("Ford");
cars.add("Duster");
// Get the iterator
Iterator<String> iterator = cars.iterator();
System.out.println("List elements : ");
while (iterator.hasNext())
System.out.print(iterator.next() + " ");
System.out.println();
}
}
Output
List elements :
Audi BMW Ford Duster
Removing elements from Collection
Iterators are designed to easily change the collections that they loop through. The remove() method can remove items from a collection while looping. In the below example, I’m deleting the items whose reminder are not 0.
public class IteratorDemo {
public static void main(String[] args) {
ArrayList<Integer> numbers = new ArrayList<Integer>();
numbers.add(20);
numbers.add(8);
numbers.add(10);
numbers.add(50);
// Get the iterator
Iterator<Integer> it = numbers.iterator();
System.out.println("List of Numbers : ");
while (it.hasNext()) {
Integer i = it.next();
if (i / 10 == 0) {
it.remove();
}
}
System.out.println(numbers);
}
}
Output
List of Numbers :
[20, 10, 50]
I hope you are cleared about Iterators now. Enjoy learning. Cheers!!
A HashMap stores items in “key/value”pairs, and you can access them by an index of another type (e.g. a String).
One object is used as a key (index) to another object (value). It can store different types: String keys and Integer values, or the same type, like String keys and String values. We need to import java.util.HashMap or its superclass in order to use the HashMap class and methods.
It is not an ordered collection, which means it does not return the keys and values in the same order in which they have been inserted into the HashMap.
HashMap<String, String> employeeDetail = new HashMap<String, String>();
HashMap<String, String> employeeDetail = new HashMap<>();
HashMap<String, Integer> employeeDetail = new HashMap<String, Integer>();
Add Items
Below is an example where we are adding items to HashMap by using put() method.
import java.util.HashMap;
public class HashMap_Demo {
public static void main(String[] args) {
/* This is how to declare HashMap of key and Value as String */
HashMap<String, String> employeeDetail = new HashMap<String, String>();
// Add keys and values (Name, Designation)
employeeDetail.put("Tim", "DBA");
employeeDetail.put("Dong", "SDET");
employeeDetail.put("Nisha", "BA");
employeeDetail.put("Ulana", "Dev");
System.out.println("Detail of Employees :" + employeeDetail);
}
}
The output of the above program is
Below is an example where we are adding items to HashMap by using put() method.
Here, the key is String, and the Value is Integer.
import java.util.HashMap;
public class HashMap_Demo {
public static void main(String[] args) {
// Combination of String(key) and Integer(value)
HashMap<String, Integer> employeeAge = new HashMap<String, Integer>();
// Add keys and values (Name, Age)
employeeAge.put("Tim", 25);
employeeAge.put("Dong", 26);
employeeAge.put("Nisha", 29);
employeeAge.put("Ulana", 34);
System.out.println("Age of Employees :" + employeeAge);
}
}
The output of the above program is
Access an Item
To access a value in the HashMap, use the get() method and refer to its key:-
import java.util.HashMap;
public class HashMap_Demo {
public static void main(String[] args) {
// Combination of String(key) and Integer(value)
HashMap<String, Integer> employeeAge = new HashMap<String, Integer>();
// Add keys and values (Name, Age)
employeeAge.put("Tim", 25);
employeeAge.put("Dong", 26);
employeeAge.put("Nisha", 29);
employeeAge.put("Ulana", 34);
System.out.println("Age of Employees :"+ employeeAge);
// Access a value
System.out.println("Access Value of Key Nisha :" + employeeAge.get("Nisha"));
}
}
The output of the above program is
Remove an Item
To remove an item, use the remove() method and refer to the key:
import java.util.HashMap;
public class HashMap_Demo {
public static void main(String[] args) {
// Combination of String(key) and Integer(value)
HashMap<String, Integer> employeeAge = new HashMap<String, Integer>();
// Add keys and values (Name, Age)
employeeAge.put("Tim", 25);
employeeAge.put("Dong", 26);
employeeAge.put("Nisha", 29);
employeeAge.put("Ulana", 34);
System.out.println("Age of Employees :" + employeeAge);
// To remove an item, use the remove() method and refer to the key
employeeAge.remove("Ulana");
System.out.println("List of Employee after removing Ulana :" + employeeAge);
}
}
The output of the above program is
To remove all items, use the clear()method:-
import java.util.HashMap;
public class HashMap_Demo {
public static void main(String[] args) {
// Combination of String(key) and Integer(value)
HashMap<String, Integer> employeeAge = new HashMap<String, Integer>();
// Add keys and values (Name, Age)
employeeAge.put("Tim", 25);
employeeAge.put("Dong", 26);
employeeAge.put("Nisha", 29);
employeeAge.put("Ulana", 34);
System.out.println("Age of Employees :" + employeeAge);
// To remove all items, use the clear() method:
employeeAge.clear();
System.out.println("List of Employes after clear:" + employeeAge);
}
}
The output of the above program is
Checking whether HashMap is empty or not
We are using isEmpty() method of the HashMap class to perform this check.
import java.util.HashMap;
public class HashMap_Demo {
public static void main(String[] args) {
/* This is how to declare HashMap */
HashMap<String, String> employeeDetail = new HashMap<String, String>();
// Add keys and values (Name, Designation)
employeeDetail.put("Tim", "DBA");
employeeDetail.put("Dong", "SDET");
employeeDetail.put("Nisha", "BA");
employeeDetail.put("Ulana", "Dev");
System.out.println("Detail of Employees :" + employeeDetail);
// Checking whether HashMap is empty or not
System.out.println("Is HashMap Empty? " + employeeDetail.isEmpty());
// Delete all items from HasMap
employeeDetail.clear();
System.out.println("Is HashMap Empty now? " + employeeDetail.isEmpty());
}
}
The output of the above program is
Check if a particular key exists in HashMap
We will be using containsKey() method of the HashMap class to perform this check. This method returns a boolean value.
import java.util.HashMap;
public class HashMap_Demo {
public static void main(String[] args) {
/* This is how to declare HashMap */
HashMap<String, String> employeeDetail = new HashMap<String, String>();
// Add keys and values (Name, Designation)
employeeDetail.put("Tim", "DBA");
employeeDetail.put("Dong", "SDET");
employeeDetail.put("Nisha", "BA");
employeeDetail.put("Ulana", "Dev");
System.out.println("Detail of Employees :" + employeeDetail);
// Check if a particular key exists in HashMap
boolean flag = employeeDetail.containsKey("Nisha");
System.out.println("Key Nisha exists in HashMap? : " + flag);
boolean flag1 = employeeDetail.containsKey("Shawn");
System.out.println("Key Shawn exists in HashMap? : " + flag1);
}
}
The output of the above program is
Check if a particular value exists in HashMap
We will be using containsValue()method of the HashMap class to perform this check.
import java.util.HashMap;
public class HashMap_Demo {
public static void main(String[] args) {
/* This is how to declare HashMap */
HashMap<String, String> employeeDetail = new HashMap<String, String>();
// Add keys and values (Name, Designation)
employeeDetail.put("Tim", "DBA");
employeeDetail.put("Dong", "SDET");
employeeDetail.put("Nisha", "BA");
employeeDetail.put("Ulana", "Dev");
System.out.println("Detail of Employees :" + employeeDetail);
// Check if a particular value exists in HashMap
boolean valueExists = employeeDetail.containsValue("Dev");
System.out.println("String Dev exists in HashMap? : " + valueExists);
boolean valueNotExists = employeeDetail.containsValue("Test");
System.out.println("String Test exists in HashMap? : " + valueNotExists);
}
}
The output of the above program is
We are done! Congratulations on making it through this tutorial and hope you found it useful! Happy Learning!!
Selects the specified property in a parent object.
[‘property’]
Selects the specified property in a parent object. Be sure to put single quotes around the property name.Tip: Use this notation if the property name contains special characters such as spaces, or begins with a character other than A..Za..z_.
[n]
Selects the n-th element from an array. Indexes are 0-based.
[index1,index2,…]
Selects array elements with the specified indexes. Returns a list.
..property
Recursive descent: Searches for the specified property name recursively and returns an array of all values with this property name. Always returns a list, even if just one property is found.
*
Wildcard selects all elements in an object or an array, regardless of their names or indexes.
[start:end] [start:]
Selects array elements from the start index and up to, but not including, end index. If end is omitted, selects all elements from start until the end of the array. Returns a list.
[:n]
Selects the first n elements of the array. Returns a list.
[-n:]
Selects the last n elements of the array. Returns a list.
[?(expression)]
Selects all elements in an object or array that match the specified filter. Returns a list.
[(expression)]
Script expressions can be used instead of explicit property names or indexes. An example is [(@.length-1)] which selects the last item in an array. Here, length refers to the length of the current array rather than a JSON field named length.
@
Used in filter expressions to refer to the current node being processed.
Below is the sample JSON which I am using for extraction examples. I have saved this file in resources/Payloads as test.json.
{
"store": {
"book": [
{
"category": "reference",
"author": "Nigel Rees",
"title": "Sayings of the Century",
"price": 8.95
},
{
"category": "fiction",
"author": "Evelyn Waugh",
"title": "Sword of Honour",
"price": 12.99
},
{
"category": "fiction",
"author": "Herman Melville",
"title": "Moby Dick",
"isbn": "0-553-21311-3",
"price": 8.99
},
{
"category": "fiction",
"author": "J. R. R. Tolkien",
"title": "The Lord of the Rings",
"isbn": "0-395-19395-8",
"price": 22.99
}
],
"bicycle": {
"color": "red",
"price": 19.95
}
},
"expensive": 10
}
To extract all books present in the store:-
String allBooks = JsonPath.read(jsonString, "$..*").toString();
System.out.println("--------------- All books in the store --------------");
System.out.println(allBooks);
The complete program looks like as shown below:
import com.jayway.jsonpath.JsonPath;
public class JsonPath_Demo {
public static void main(String args[]) {
String jsonString = new String(Files.readAllBytes(Paths.get("src/test/resources/Payloads/test.json")));
String allBooks = JsonPath.read(jsonString, "$..*").toString();
System.out.println("--------------- All books in the store --------------");
System.out.println(allBooks);
}
}
The output of the above program is
Below are examples that show how to extract different nodes from a JSON Body. I have used the above JSON Body for these examples.
// All bicycles in the store
String allBicycles = JsonPath.read(jsonString, "$..bicycle").toString();
System.out.println("--------------- All bicycles in the store ---------------");
System.out.println(allBicycles);
// The number of books
String noOfBooks = JsonPath.read(jsonString, "$..book.length()").toString();
System.out.println("--------------- The number of books ---------------");
System.out.println(noOfBooks);
// The authors of all books
String authors = JsonPath.read(jsonString, "$.store.book[*].author").toString();
System.out.println("--------------- Author of all Books ---------------");
System.out.println(authors);
// All authors
String allAuthors = JsonPath.read(jsonString, "$..author").toString();
System.out.println("--------------- All Authors ---------------");
System.out.println(allAuthors);
// All details of the store
String store = JsonPath.read(jsonString, "$.store.*").toString();
System.out.println("--------------- All details of the store ---------------");
System.out.println(store);
// Price of store
String storePrice = JsonPath.read(jsonString, "$.store..price").toString();
System.out.println("--------------- price of store ---------------");
System.out.println(storePrice);
The output of the above program is
Below are the examples where I have extracted specific book (nodes) from the JSON body.
// Third book
String thirdBook = JsonPath.read(jsonString, "$..book[2]").toString();
System.out.println("--------------- third book ---------------");
System.out.println(thirdBook);
// first Last Book
String firstLastBook = JsonPath.read(jsonString, "$..book[-1]").toString();
System.out.println("--------------- first Last Book ---------------");
System.out.println(firstLastBook);
// first two Books
String firstTwoBooks = JsonPath.read(jsonString, "$..book[0,1]").toString();
System.out.println("--------------- first Two Books ---------------");
System.out.println(firstTwoBooks);
// books from index 0 (inclusive) until index 2 (exclusive)
String booksRange = JsonPath.read(jsonString, "$..book[:2]").toString();
System.out.println("--------------- books from index 0 (inclusive) until index 2 (exclusive) ---------------");
System.out.println(booksRange);
// All books from index 1 (inclusive) until index 2 (exclusive)
String booksRange1 = JsonPath.read(jsonString, "$..book[1:2]").toString();
System.out.println("------------ All books from index 1 (inclusive) until index 2 (exclusive) -----------");
System.out.println(booksRange1);
// Book number one from tail
String bottomBook = JsonPath.read(jsonString, "$..book[1:]").toString();
System.out.println("--------------- Book number one from tail ---------------");
System.out.println(bottomBook);
The output of the above program is
Filters are logical expressions used to filter arrays. Below are examples of a JSONPath expression with the filters.
// All books in store expensive than 10
String expensiveBook = JsonPath.read(jsonString, "$.store.book[?(@.price > 10)]").toString();
System.out.println("--------------- All books in store costlier than 10 ---------------");
System.out.println(expensiveBook);
// All books in store that are not "expensive"
String notExpensiveBook = JsonPath.read(jsonString, "$..book[?(@.price <= $['expensive'])]").toString();
System.out.println("--------------- All books in store that are not expensive ---------------");
System.out.println(notExpensiveBook);
// All books in store that are equal to price 8.95
String comparePrice = JsonPath.read(jsonString, "$.store.book[?(@.price == 8.95)]").toString();
System.out.println("--------------- All books in store that are not expensive ---------------");
System.out.println(comparePrice);
// All books matching regex (ignore case)
String regxExample = JsonPath.read(jsonString, "$..book[?(@.author =~ /.*REES/i)]").toString();
System.out.println("--------------- All books matching regex (ignore case) ---------------");
System.out.println(regxExample);
// All books with price equal to mentioned list of prices
String priceList = JsonPath.read(jsonString, "$..book[?(@.price in ['12.99', '8.99'])]").toString();
System.out.println("--------------- All books with price equal to mentioned list of prices ---------------");
System.out.println(priceList);
// All books with price NOT equal to mentioned list of prices
String excludePriceList = JsonPath.read(jsonString, "$..book[?(@.price nin ['12.99', '8.99'])]").toString();
System.out.println("---------- All books with price NOT equal to mentioned list of prices ---------");
System.out.println(excludePriceList);
// All books with specified substring (case-sensitive)
String substringExample = JsonPath.read(jsonString, "$..book[?(@.author contains 'Melville')]").toString();
System.out.println("--------------- All books with specified substring (case-sensitive) ---------------");
System.out.println(substringExample);
// All books with an ISBN number
String specificBook = JsonPath.read(jsonString, "$..book[?(@.isbn)]").toString();
System.out.println("--------------- All books with an ISBN number ---------------");
System.out.println(specificBook);
The output of the above program is
We are done! Congratulations on making it through this tutorial and hope you found it useful! Happy Learning!!
In the last tutorial, I explained How to test POST Request using Rest Assured where the request body is in String Format. In this tutorial, I will create a request body using JSON Object in Rest Assured. This request body can be used for POST or PUT operations.
In the previous post, you must have observed that I had hard-coded the JSON request body in a string format. It is not a good practice if you have a dynamic payload or want to create a payload at run time or parameterized one. It is always recommended to create a payload in a way that is easy to maintain. You should manage, update, and retrieve value from it easily. This can be achieved by JSONObjector JSONArray.
A JSONObjectis an unordered collection of key and value pairs, resembling Java’s native Map implementations. JSON stores data as a key-value pair. The key is the left side and the value is the right side, and a semicolon is used to separate both. One key-value pair is separated from another key-value pair using a comma (,).
The internal form is an object having the get and opt methods for accessing the values by name and put methods for adding or replacing values by name. The values can be any of these types:Boolean, JSONArray, JSONObject, Number, String, or JSONObject.NULL object.
To create a request body using JSON Object, we need to add a Maven dependency.
JSONObjectexposes an API similar to Java’s Map interface. Below is an example of creating a request from a JSON Object. Here, Id is the auto-generated attribute. We are using the put() method and supply the key and value as an argument. I am using a logger just to print the JSON body in the Console.
import io.restassured.RestAssured;
import io.restassured.http.ContentType;
import org.json.JSONObject;
import org.junit.Test;
import static org.hamcrest.Matchers.equalTo;
public class Json_Demo {
@Test
public void passBodyAsJsonObject() {
JSONObject data = new JSONObject();
data.put("employee_name", "MapTest");
data.put("profile_image", "test.png");
data.put("employee_age", "30");
data.put("employee_salary", "11111");
RestAssured
.given()
.contentType(ContentType.JSON)
.body(data.toString())
.log().all()
.when()
.post("https://dummy.restapiexample.com/api/v1/create")
.then()
.assertThat().statusCode(200)
.body("data.employee_name", equalTo("MapTest"))
.body("data.employee_age", equalTo("30"))
.body("data.employee_salary", equalTo("11111"))
.body("data.profile_image", equalTo("test.png"))
.body("message", equalTo("Successfully! Record has been added."))
.log().all();
}
}
The request body will look as shown below:-
The texts produced by the toString() methods strictly conform to the JSON syntax rules.
.body(data.toString())
The above one is a simple JSON Request Body. Let’s take an example of a Complex Request Body or nested Request Body.
We need to create two JSONObject here. One will hold overall key-value pairs, and another JSONObject will hold only employee_details key-value pairs.
Below is an example that shows how to create a complex JSON request body using JSONObject.
@Test
public void passBodyAsJsonObjectDemo() {
//First JSONObject
JSONObject data = new JSONObject();
data.put("profile_image", "test.png");
//Second JSONObject
JSONObject detail = new JSONObject();
detail.put("updated_message", "Details of New Resource");
detail.put("employee_age", "30");
data.put("employee_details", detail);
data.put("employee_name", "MapTest");
data.put("employee_salary", "11111");
RestAssured
.given()
.contentType(ContentType.JSON)
.body(data.toString())
.log().all()
.when()
.post("http://dummy.restapiexample.com/api/v1/create")
.then()
.assertThat().statusCode(200)
.body("data.employee_name", equalTo("MapTest"))
.body("data.employee_details.employee_age", equalTo("30"))
.body("data.employee_details.updated_message", equalTo("Details of New Resource"))
.body("data.employee_salary", equalTo("11111")).body("data.profile_image", equalTo("test.png"))
.body("message", equalTo("Successfully! Record has been added."))
.log().all();
}
}
The request body will look as shown below:-
We are done. Congratulations on making it through this tutorial and hope you found it useful! Happy Learning!!
QA Automation Expert 