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JSON Articles
Page 2 of 16
When to use @JsonValue annotation using Jackson in Java?\\n
In Java, Jackson is a library that is used to convert JSON to Java objects and vice versa. Jackson Annotations are used during serialization and deserialization. We use these to denote or specify annotations before a particular field or method (that is declared in Java). Using an annotation before a field, we can denote whether it is a variable, is a JsonProperty, should be ignored, or what condition should be applied to it. So basically, Annotations make JSON output clearer as we required. In this Article, we will learn about ...
Read MoreHow to convert a JSON to Java Object using the Jackson library in Java?
Jackson is a Java library that is used to convert JSON to Java objects and vice versa. Conversion of JSON to a Java object is called deserialization, and Java object to JSON is known as serialization. Both of these tasks can be done by using the Jackson library. In this article, we are going to learn how to convert JSON to Java objects using the Jackson library. Jackson Library: Convert a JSON to a Java Object The ObjectMapper class belongs to the Jackson library. This class is responsible for the serialization and deserialization of Java objects. The ObjectMapper class is used ...
Read MoreHow to access the JSON fields, arrays and nested objects of JsonNode in Java?
What are JSON and JsonNode? JSON is a format that is used to store data and exchange data between a server and a client. To know more about JSON, you can refer to the JSON Tutorial. A JsonNode is Jackson's tree model for JSON. To read JSON into a JsonNode with Jackson by creating an ObjectMapper instance and call the readValue() method. We can access a field, array or nested object using the get() method of the JsonNode class. We can return a valid string representation using the asText() method and ...
Read MoreHow to serialize a null field using Gson library in Java?
Gson is a library in the Java that is mainly used for converting Java objects to JSON and vice versa. By default, the Gson object does not serialize the fields with null values to JSON. If a field in a Java object is null, Gson excludes it.Serializing a Null Field Using Gson We can force Gson to serialize null values via the GsonBuilder class. We need to call the serializeNulls() method on the GsonBuilder instance before creating the Gson object. Once serializeNulls() has been called, the Gson instance created by the GsonBuilder can include null fields in the serialized JSON. ...
Read MoreHow to deserialize a JSON into an existing object in Java?
Deserialization is the process of converting a JSON string into a Java object. In this example, we will learn how to deserialize a JSON string into an existing object in Java. There are libraries available in Java that can help us to deserialize a JSON string into an existing object. Some of the popular libraries are: Using Gson Using Jackson Using Flexjson Let's learn how to use each of these libraries to deserialize a JSON string into an existing object in Java. Deserializing JSON Object Using ...
Read MoreDifferences between fromJson() and toJson() methods of Gson in Java?
Gson is a Java library which is developed by Google and used to convert Java objects into JSON and vice versa. It is mostly used in applications where data can be exchanged in JSON format. There are two useful methods in Gson that we are going to discuss in this article. These methods are fromJson() and toJson(). The fromJson() Method The fromJson() method is used to convert a JSON string into a Java object. It takes two parameters: the JSON string and the class type of the object you want to create. Here is the syntax of the fromJson() method: ...
Read MoreHow to serialize a map using the flexjson library in Java?\\n
Serializing a Map in Java is the process of converting a Map object into a format that can be easily stored or transmitted, such as JSON or XML. We will use the Flexjson library to serialize a map in Java. We can serialize a Map using the serialize() method of the JSONSerializer class, which performs a shallow serialization of the target instance. Example of Serializing a Map We will take a map and see the output after serialization. Map map = new HashMap(); map.put("name", "Ansh"); map.put("age", "23"); map.put("city", "Mumbai"); map.put("country", "India"); After serialization, the map will look like this: {"name":"Ansh", ...
Read MoreHow to parse a JSON without duplicate keys using Gson in Java?
Parsing a JSON without duplicate keys means converting a JSON string into a Java object. But we need to keep in mind that the JSON string should not have duplicate keys. Gson: Parsing a JSON Without Duplicate Keys We can use the Gson library to parse a JSON without duplicate keys in Java. It is developed by Google and used for converting Java objects into JSON and vice versa. By default, Gson does not allow duplicate keys in JSON. If a JSON string has duplicate keys, Gson will throw a JsonSyntaxException. We will use the methods fromJson() and toJson() to achieve ...
Read MoreHow can we create a JSON using JsonGenerator in Java?
JSON is a format for storing and exchanging data. It is easily readable and also easy to parse. Creating JSON Using Java JsonGenerator In Java, we can create a JSON object using the JsonGenerator class. JsonGenerator is class in the javax.json.stream package that is used to create JSON data. It provides methods to write JSON objects, arrays, and values. To use the JsonGenerator class, we need to add the javax.json library to our project. If you are using Maven, add this to your pom.xml file: javax.json javax.json-api 1.1.4 If you are not using Maven, you can download ...
Read MoreCustom instance creator using Gson in Java?
While parsing a JSON String to or from a Java object, by default, Gson tries to create an instance of the Java class by calling the default constructor. In the case of Java, if a class doesn’t contain a default constructor or we want to do some initial configuration while creating Java objects, we need to create and register our own instance creator. Custom Instance Creator Using Gson Custom instance means creating a new instance that is not the default. In this instance, we can add whatever properties we want. There are many libraries that create custom instances. In this ...
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