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Object Oriented Programming Articles
Page 436 of 589
When can we call @JsonAnyGetter and @JsonAnySetter annotations in Java?
The @JsonAnyGetter annotation enables to use a Map as a container for properties that we want to serialize to JSON and @JsonAnySetter annotation instructs Jackson to call the same setter method for all unrecognized fields in the JSON object, which means that all fields that are not already mapped to a property or setter method in the Java object.Syntaxpublic @interface JsonAnyGetter public @interface JsonAnyGetterExampleimport java.io.*; import java.util.*; import com.fasterxml.jackson.core.*; import com.fasterxml.jackson.databind.*; import com.fasterxml.jackson.annotation.*; public class JsonAnyGetterAndJsonAnySetterTest { public static void main(String args[]) throws JsonGenerationException, JsonMappingException, IOException { Employee emp1 = new ...
Read MoreConvert CSV to JSON using the Jackson library in Java?
A Jackson is a Java JSON API that provides several different ways to work with JSON. We can convert CSV data to JSON data using the CsvMapper class, it is specialized ObjectMapper, with extended functionality to produce CsvSchema instances out of POJOs. We can use the reader() method for constructing ObjectReader with default settings. In order to convert this, we need to import the com.fasterxml.jackson.dataformat.csv package.In the below example, convert a CSV to JSON.Exampleimport java.io.*; import java.util.*; import com.fasterxml.jackson.databind.*; import com.fasterxml.jackson.dataformat.csv.*; public class CsvToJsonTest { public static void main(String args[]) throws Exception { ...
Read MoreHow to deserialize a JSON array to list generic type in Java?
The Gson library provides a class called com.google.gson.reflect.TypeToken to store generic types by creating a Gson TypeToken class and pass the class type. Using this type, Gson can able to know the class passed in the generic class.Syntaxpublic class TypeToken extends ObjectWe can deserialize a JSON array to a generic type of list in the below exampleExampleimport java.lang.reflect.Type; import java.util.*; import com.google.gson.*; import com.google.gson.reflect.*; public class JSONArrayToListTest { public static void main(String args[]) throws Exception { String jsonStr = "[{"name":"Adithya", "course":"Java"}, " + "{"name":"Ravi", "course":"Python"}]"; ...
Read MoreRename multiple files using Java
Following is the code to rename multiple files using Java −Exampleimport java.io.File; import java.io.IOException; public class Demo{ public static void main(String[] argv) throws IOException{ String path_to_folder = "path\to\folder\where\multiple\files\are\present"; File my_folder = new File(path_to_folder); File[] array_file = my_folder.listFiles(); for (int i = 0; i < array_file.length; i++){ if (array_file[i].isFile()){ File my_file = new File(path_to_folder + "" + array_file[i].getName()); String long_file_name = array_file[i].getName(); String[] my_token = long_file_name.split("\s"); ...
Read MoreJar files in Java
JAR is a file format that helps in aggregating Java class file, along with its associated metadata and resources into a single file.Creation of a JAR file − The jar cf command can be used, where ‘cf’ means creating the file.jar cf jar_file_name files_to_compressOnce a jar file has been created, a default manifest file is also created. Only one manifest file is present in a specific archive, and it will have the extension ‘mf’ and will be in the pathname. Thismanifest file helps give information about the files that have been compressed/present in the package.Viewing a JAR file − The ...
Read MoreInteresting Facts about Java
Java was built by sheer accident, a team of developers were busy building a set top box, and began cleaning C++. When they were winding up these changes, they ended up discovering Java and its runtime environment.Many of you might be aware of this, but for those who aren’t, Java wasn’t the original name that was decided for this language. It was ‘Oak’. Sun Marketing system changed the name later when they realized that a company named ‘Oak’ existed.It is a widely used language all over the world, and is considered to be a favourite amongst the developer group, and ...
Read MoreHow can we decode a JSON object in Java?
A JSON is a lightweight, text-based and language-independent data exchange format. A JSON can represent two structured types like objects and arrays. We can decode a JSON object using JSONObject and JSONArray from json.simple API. A JSONObject works as a java.util.Map whereas JSONArray works as a java.util.List.In the below example, we can decode a JSON object.Exampleimport org.json.simple.*; import org.json.simple.parser.*; public class JSONDecodingTest { public static void main(String[] args) { JSONParser parser = new JSONParser(); String str = "[ 0 , {"1" : { "2" : ...
Read MoreHow can we encode a JSON object in Java?
A JSONObject is a subclass of java.util.HashMap where no order is provided. We can also use the strict ordering of elements as well with the help of the JSONValue.toJSONString(map) method i.e. by the implementation of java.util.LinkedHashMap.We can encode a JSON object in the below two examples.Example import java.util.*; import org.json.simple.JSONObject; public class JSONEncodingTest { public static void main(String[] args) { Map dataMap = new HashMap(); dataMap.put("Name", "Adithya"); dataMap.put("Age", new Integer(25)); dataMap.put("Salary", new Double(25000.00)); dataMap.put("Employee Id", new Integer(115)); dataMap.put("Company", "TutorialsPoint"); JSONObject ...
Read MoreHow can we convert a map to the JSON object in Java?
The JSON is a lightweight, text-based and language-independent data exchange format. The JSON can represent two structured types like objects and arrays. An object is an unordered collection of key/value pairs and an array is an ordered sequence of values. We can convert a Map to JSON object using the toJSONString() method(static) of org.json.simple.JSONValue. It has two important static methods: writeJSONString() method to encode an object into JSON text and write it out, escape() method to escape the special characters and escape quotes, \, /, \r, , \b, \f, \t.Exampleimport java.util.*; import org.json.simple.JSONValue; public class ConvertMapJSONTest { ...
Read MoreHow can we add a JSONArray to JSONObject in Java?
The JSON is a text-based format for exchanging data. It is a lightweight component and language independent. We can also add a JSONArray to JSONObject. We need to add a few items to an ArrayList first and pass this list to the put() method of JSONArray class and finally add this array to JSONObject using the put() method. Exampleimport org.json.*; import java.util.*; public class AddJSONArrayToJSONObjTest { public static void main(String args[]) { List list = new ArrayList(); list.add("Raja"); list.add("Jai"); ...
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