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Java Articles
Page 290 of 450
How to convert bean to JSON object by excluding some properties using JsonConfig in Java?
The JsonConfig class is a utility class that helps to configure the serialization process. We can convert a bean to a JSON object with few properties that can be excluded using the setExcludes() method of JsonConfig class and pass this JSON config instance to an argument of static method fromObject() of JSONObject.Syntaxpublic void setExcludes(String[] excludes)In the below example, we can convert bean to a JSON object by excluding some of the properties.Exampleimport net.sf.json.JSONObject; import net.sf.json.JsonConfig; public class BeanToJsonExcludeTest { public static void main(String[] args) { Student student = new Student("Raja", "Ramesh", ...
Read MoreHow to add elements to JSON Object using JSON-lib API in Java?
The JSON-lib is a Java library for serializing and de-serializing java beans, maps, arrays, and collections in JSON format. We can add elements to the JSON object using the element() method of JSONObject class. We need to download all the dependent jars like json-lib.jar, ezmorph.jar, commons-lang.jar, commons-collections.jar, commons-beanutils.jar, and commons-logging.jar and can import net.sf.json package in our java program to execute it.Syntaxpublic JSONObject element(String key, Object value) - put a key/value pair in the JSONObject Exampleimport java.util.Arrays; import net.sf.json.JSONObject; public class JsonAddElementTest { public static void main(String[] args) { JSONObject jsonObj ...
Read MoreHow to serialize and deserialize a JSON using the ExclusionStrategy interface in Java?
The ExclusionStrategy interface can be used to exclude any field during serialization and deserialization. We can provide a custom implementation of the ExclusionStrategy interface and need to register it with GsonBuilder using the setExclusionStrategies() method. It configures Gson to apply a set of exclusion strategies during serialization and deserialization.Syntaxpublic GsonBuilder setExclusionStrategies(ExclusionStrategy... strategies)Exampleimport com.google.gson.*; import com.google.gson.ExclusionStrategy; import com.google.gson.FieldAttributes; public class ExclusionStrategyTest { public static void main(String args[]) throws Exception { Gson gson = new GsonBuilder().setExclusionStrategies(new CustomExclusionStrategy()).create(); Person person = new Person(); ...
Read MoreHow can we update an existing JSON data using javax.json API in Java?
The JsonBuilderFactory interface is a factory to create JsonObjectBuilder instance and JsonObjectBuilder is a builder for creating JsonObject models from scratch. This interface initializes an empty JSON object model and provides methods to add name/value pairs to the object model and to return the resulting object. We can create a JsonObjectBuilder instance that can be used to build JsonObject using the createObjectBuilder() method.SyntaxJsonObjectBuilder createObjectBuilder()In the below example, We can update an existing JSON data with newly added data.Exampleimport java.io.*; import javax.json.*; public class UpdateExistingJsonTest { public static void main(String[] args) throws Exception { ...
Read MoreJSON Schema Support using Jackson in Java?
JSON Schema is a specification for JSON based format for defining the structure of JSON data. The JsonSchema class can provide a contract for what JSON data is required for a given application and how to interact with it. The JsonSchema can define validation, documentation, hyperlink navigation, and interaction control of JSON data. We can generate the JSON schema using the generateSchema() method of JsonSchemaGenerator, this class wraps the JSON schema generation functionality.Syntaxpublic JsonSchema generateSchema(Class type) throws com.fasterxml.jackson.databind.JsonMappingExceptionExampleimport com.fasterxml.jackson.core.JsonProcessingException; import com.fasterxml.jackson.databind.ObjectMapper; import com.fasterxml.jackson.module.jsonSchema.JsonSchema; import com.fasterxml.jackson.module.jsonSchema.JsonSchemaGenerator; import java.util.List; public class JSONSchemaTest { public static void main(String[] args) throws ...
Read MoreHow to convert Java array or ArrayList to JsonArray using Gson in Java?
The Java Arrays are objects which store multiple variables of the same type, it holds primitive types and object references and an ArrayList can represent a resizable list of objects. We can add, remove, find, sort and replace elements using the list. A JsonArray can parse text from a string to produce a vector-like object. We can convert an array or ArrayList to JsonArray using the toJsonTree().getAsJsonArray() method of Gson class.Syntaxpublic JsonElement toJsonTree(java.lang.Object src)Exampleimport com.google.gson.*; import java.util.*; public class JavaArrayToJsonArrayTest { public static void main(String args[]) { String[][] strArray = {{"elem1-1", ...
Read MoreHow to resolve "Expected BEGIN_OBJECT but was BEGIN_ARRAY" using Gson in Java?
While deserializing, a Gson can expect a JSON object but it can find a JSON array. Since it can't convert from one to the other, it can throw an error as "JsonSyntaxException: java.lang.IllegalStateException: Expected BEGIN_OBJECT but was BEGIN_ARRAY" at the runtime.Exampleimport com.google.gson.Gson; public class GsonErrorTest { public static void main(String args[]) throws Exception { String json = "{"employee":[{"name":"Raja Ramesh", "technology":"java"}]}"; Gson gson = new Gson(); Software software = gson.fromJson(json, Software.class); System.out.println(software); ...
Read MoreHow to serialize a JSON object with JsonWriter using Object Model in Java?
The javax.json.JsonWriter interface can write a JSON object or array structure to an output source. The class javax.json.JsonWriterFactory contains methods to create JsonWriter instances. A factory instance can be used to create multiple writer instances with the same configuration. We can create writers from output source using the static method createWriter() of javax.json.Json class.Syntaxpublic static JsonWriter createWriter(Writer writer)In the below example, we can serialize a JSON object using the JsonWriter interface.Exampleimport java.io.StringWriter; import javax.json.Json; import javax.json.JsonObject; import javax.json.JsonObjectBuilder; import javax.json.JsonWriter; public class JsonWriterTest { public static void main(String[] args) { JsonObject ...
Read MoreHow to handle the errors generated while deserializing a JSON in Java?
The DeserializationProblemHandler class can be registered to get called when a potentially recoverable problem is encountered during the deserialization process. We can handle the errors generated while deserializing the JSON by implementing the handleUnknownProperty() method of DeserializationProblemHandler class.Syntaxpublic boolean handleUnknownProperty(DeserializationContext ctxt, JsonParser p, JsonDeserializer deserializer, Object beanOrClass, String propertyName) throws IOExceptionExampleimport java.io.*; import com.fasterxml.jackson.core.*; import com.fasterxml.jackson.databind.*; import com.fasterxml.jackson.databind.deser.*; public class DeserializationErrorTest { public static void main(String[] args) throws JsonMappingException, JsonGenerationException, IOException { String jsonString = "{"id":"101", "name":"Ravi Chandra", "address":"Pune", "salary":"40000" }"; ObjectMapper objectMapper = new ...
Read MoreHow to merge two JSON strings in an order using JsonParserSequence in Java?
The JsonParserSequence is a helper class that can be used to create a parser containing two sub-parsers placed in a particular sequence. We can create a sequence using the static method createFlattened() of the JsonParserSequence class.Syntaxpublic static JsonParserSequence createFlattened(JsonParser first, JsonParser second)Exampleimport java.io.*; import com.fasterxml.jackson.core.*; import com.fasterxml.jackson.core.util.*; public class JsonParserSequenceTest { public static void main(String[] args) throws JsonParseException, IOException { String jsonString1 = "{"id":"101", "name":"Ravi Chandra", "address":"Pune"}"; String jsonString2 = "{"id":"102", "name":"Raja Ramesh", "address":"Hyderabad", "contacts":[{"mobile":"9959984805", "home":"7702144400"}]}"; JsonFactory jsonFactory = ...
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