Gson fromJson Method Example

Gson fromJson method example shows how to use the fromJson method of the Gson class to convert string to JSON object in Java.

The fromJson method of the Gson class is used to parse the string data into the specified class.

public <T> T fromJson(java.lang.String json,

java.lang.Class<T> classOfT)

throws JsonSyntaxException

The first argument to the fromJson method is the string containing JSON data, and the second argument is the class. Here is an example that converts a string to a generic JsonObject using the Gson library.

package com.javacodeexamples.gsonexamples;

import com.google.gson.Gson;

import com.google.gson.JsonObject;

public class GsonFromJsonExample {

public static void main(String[] args) {

* String containing JSON data.

String data = "{\"Id\": \"EMP002\",\"Name\": \"John\",\"Age\": 41,\"IsManager\": true}";

* Using the fromJson method we can convert the

* string to a JsonObject

JsonObject jsonObject = new Gson().fromJson(data, JsonObject.class);

//access the object properties

System.out.println("ID: " + jsonObject.get("Id").getAsString());

System.out.println("Name: " + jsonObject.get("Name").getAsString());

}

Output

1 2	ID: EMP002 Name: John

The above example uses the fromJson method to convert the string to a generic JsonObject.

We can also use the same method to convert data to a pojo class as given below.

package com.javacodeexamples.gsonexamples;

import com.google.gson.Gson;

public class GsonFromJsonExample {

public static void main(String[] args) {

* String containing JSON data.

String data = "{\"Id\": \"EMP002\",\"Name\": \"John\",\"Age\": 41,\"IsManager\": true}";

* Using the fromJson method we can convert the

* string to a POJO object as well

Emp employee = new Gson().fromJson(data, Emp.class);

//access the object properties

System.out.println("ID: " + employee.getId());

System.out.println("Name: " + employee.getName());

System.out.println("Age: " + employee.getAge());

System.out.println("IsManager: " + employee.getIsManager());

}

* Employee POJO class

class Emp{

private String Id;

private String Name;

private String Age;

private boolean IsManager;

public String getId() {

return Id;

}

public void setId(String id) {

Id = id;

}

public String getName() {

return Name;

}

public void setName(String name) {

Name = name;

}

public String getAge() {

return Age;

}

public void setAge(String age) {

Age = age;

}

public boolean getIsManager() {

return IsManager;

}

public void setIsManager(boolean isManager) {

IsManager = isManager;

}

Output

ID: EMP002

Name: John

Age: 41

IsManager: true

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