Skip to main content

JSON Manipulation in Java

JSON stands for Java Script Object Notation, in which essentially we represent data in name:value pair in a string.

Example of JSON strin is as follows

   "city":"Foster City",
Which represent the Data about a user. JSON is a standard notation to exchange data.

To process Json String , like converting from Json String to Java or vice versa we have
so many different libraries in Java.One of the Most prominent being Jackson,

Bellow are the example or Some Use cases for Handling Json in Java.

Converting JSON String to Java Object Using Jackson

We can use ObjectMapper to convert a JSON String to java Object.

ObjectMapper mapper = new ObjectMapper();
UserInfo userInfoObj = mapper.readValue(JSONStringSrc,  UserInfo.class);

Where UserInfo Object is a POJO class with appropriate Jackson Annotations.
If we want to hide or not map some of the properties from JSON  string with Java object
we can use @JsonIgnoreProperties annotations to ignore any  unmapped fields.
Converting JSON String to Java Map Using Jackson

ObjectMapper mapper = new ObjectMapper();
Map userInfoObj = mapper.readValue(JSONStringSrc, new TypeReference>() {});
Converting Java Object to JSON String
Jackson provide a methond writeValueAsString which converts a mapped Object to json string


Popular posts from this blog

Masking Credit Card number in Java

Sometimes we need to mask crucial information like Credit Card Numbers, CVV numbers etc before storing  or logging the information. This example mask Credit Card Number (Except last 4 Digit) from a Text which contains information along with Credit Card Number.

The following example demonstrates how we can easily mask the credit card with Matcher and Pattern Classes. This Sample Code uses Matcher and Pattern.
Pattern Used in this sample is not optimized for Credit Card Numbers, this pattern will get any numerical numbers in the String Content.  Based on the Credit Card Type a more efficient and Strict RegEx can be used to mask the Credit Card.
/**Mask the Credit card number but last four digit value **/   Pattern PATTERN = Pattern.compile("[0-9]+"); String message = content; Matcher matcher = PATTERN.matcher(message); String maskingChar = "*"; StringBuilder finalMask = new StringBuilder(maskingChar); while …

Converting Java Map to String

Java Collections framework, String manipulation etc is something that we often encounter in Development process.
For processing collections (like checking null/empty, Intersection, Disjunction) We do have some of the very use full libraries.

Some of the Collection related libraries are Apche Commons Collections and Google  Collections(Guava).

Problem Use Case

This article explains how to convert a Java Map to String(and vice versa) using different libraries and technique.

One way is to use StringBuilder(Or String) and loop though the Map and build the String by applying some sort of separator ( for key:value and entry). Here we have to take care of the null value etc.

Without Any Library
If we want to convert the map to a String with key value separator and also individual entry seperator in the resulting String, we have to write code for that. For a simple Map, we have to iterate though the map, take care of the null values etc. Following is a sample to get String built out from Map C…

Invoking EJB deployed on a remote machine

Invoking EJB deployed on a remote machineIn case we are calling remote ejb( ejb deployed on remote machines),The JNDI lookup might lookup like,Properties env = new Properties();env.put(Context.INITIAL_CONTEXT_FACTORY, "org.jnp.interfaces.NamingContextFactory");env.put(Context.PROVIDER_URL, "XX.XXX.XX.XX:1099");env.put("java.naming.factory.url.pkgs", "org.jboss.naming:org.jnp.interfaces"); Context ctx = new InitialContext(env);If we are calling local ejb then we can simply create InitialContext without any parameters.Like,Context ctx = new InitialContext();