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How to convert the following json string to java object?

java
object-mapping
json-conversion
jackson-library
Alex KataevbyAlex Kataev·Dec 31, 2024
TLDR

Easily convert a JSON string into a Java object with the help of Jackson's ObjectMapper. Align your Java class fields with @JsonProperty, instantiate ObjectMapper, and invoke readValue():

import com.fasterxml.jackson.annotation.JsonProperty; import com.fasterxml.jackson.databind.ObjectMapper; public class MyObject { // Mapping JSON property to Java field. Isn't it fun? 😉 @JsonProperty("property1") private String property1; @JsonProperty("property2") private int property2; // The magic getters and setters go here } String json = "{\"property1\":\"value1\",\"property2\":10}"; MyObject myObj = new ObjectMapper().readValue(json, MyObject.class);

Conquering complex JSON

Your JSON may look like the entire Lord of the Rings plot! Fret not. Create a Java class hierarchy corresponding to the JSON structure. Create separate classes for nested JSON objects or arrays.

public class MusicCollection { // Imagine 'mymusic' is a legion of complex nested JSON objects with guitars private List<Music> mymusic; // More properties live here, together with getters and setters } public class Music { private String artist; private String title; // Even more properties and their getter/setter friends reside here }

Calling ObjectMapper will handle nested objects like a pro:

String complexJson = "{\"mymusic\":[{\"artist\":\"Artist Name\",\"title\":\"Song Title\"}]}"; MusicCollection musicCollection = new ObjectMapper().readValue(complexJson, MusicCollection.class);

Embrace the chaos — error handling

Your bugs are not errors, they are unintended features! Jokes aside, it helps to catch exceptions during JSON conversion for error-free code:

try { MyObject myObj = new ObjectMapper().readValue(json, MyObject.class); } catch (IOException e) { e.printStackTrace(); // Code screaming? Handle it! }

Going ahead with Gson

If you are a fan of the Gson library, you can perform similar magic:

import com.google.gson.Gson; import com.google.gson.annotations.SerializedName; public class MyObject { // JSON property and Java field are now best friends! @SerializedName("property1") private String property1; @SerializedName("property2") private int property2; // Surprise surprise... getters and setters! } String json = "{\"property1\":\"value1\",\"property2\":10}"; MyObject myObj = new Gson().fromJson(json, MyObject.class);

In the Gson world, you can customize deserialization using GsonBuilder. It's the VIP lounge for JSON, inclusive for all pre-existing objects.

Checkmate tips for success

  • Validate your JSON string—cleanliness is next to godliness.
  • For JSON arrays, Jackson’s TypeReference is your knight in shining armor.
  • Does your JSON make you feel like you're in maze? Jackson's tree model can light up your path.
  • Keep your castle tidy—organize your code with separate classes to reflect JSON structure.