Jackson – Convert JSON Array of Objects to List
Hello everyone, Here we will show how to convert JSON array String to List
The Jackson library is composed of three components: Jackson Databind, Core, and Annotation. Jackson Databind has internal dependencies on Jackson Core and Annotation. Therefore, adding Jackson Databind to your Maven POM dependency /Gradle list will include the other dependencies as well.
Maven (pom.xml)
<dependency>
<groupId>com.fasterxml.jackson.core</groupId>
<artifactId>jackson-databind</artifactId>
<version>2.9.8</version>
</dependency>
Gradle (build.gradle)
implementation group: 'com.fasterxml.jackson.core',
name: 'jackson-core', version: '2.13.2'
JSON Array of Objects
[
{
"name": "knowledgefactory1",
"salaray": 1000
},
{
"name": "knowledgefactory2",
"salaray": 1200
}
]
Create an object to map the above JSON fields.
package com.knf;
public class Employee {
String name;
Double salaray;
public String getName() {
return name;
}
public void setName(String name) {
this.name = name;
}
public Double getSalaray() {
return salaray;
}
public void setSalaray(Double salaray) {
this.salaray = salaray;
}
@Override
public String toString() {
return "Employee [name=" + name + ",
salaray=" + salaray + "]";
}
}
Convert the JSON array string to a List
package com.knf;
import com.fasterxml.jackson.core.type.TypeReference;
import com.fasterxml.jackson.databind.ObjectMapper;
import java.io.IOException;
import java.util.Arrays;
import java.util.List;
public class JacksonArrayExample {
public static void main(String[] args) {
ObjectMapper mapper = new ObjectMapper();
String json =
"[{\"name\":\"knowledgefactory1\", \"salaray\":1000},
{\"name\":\"knowledgefactory2\", \"salaray\":1200}]";
try {
// 1. convert JSON array to Array objects
Employee[] pp1 = mapper.
readValue(json, Employee[].class);
System.out.println("JSON array to Array objects...");
for (Employee person : pp1) {
System.out.println(person);
}
// 2. convert JSON array to List of objects
List<Employee> ppl2 = Arrays.asList(mapper.readValue
(json, Employee[].class));
System.out.println("\nJSON array to List of objects");
ppl2.stream().forEach(x -> System.out.println(x));
// 3. alternative
List<Employee> pp3 = mapper.readValue(json,
new TypeReference<List<Employee>>() {});
System.out.println("\nAlternative...");
pp3.stream().forEach(x -> System.out.println(x));
} catch (IOException e) {
e.printStackTrace();
}
}
}
Output:
JSON array to Array objects...
Employee [name=knowledgefactory1, salaray=1000.0]
Employee [name=knowledgefactory2, salaray=1200.0]
JSON array to List of objects
Employee [name=knowledgefactory1, salaray=1000.0]
Employee [name=knowledgefactory2, salaray=1200.0]
Alternative...
Employee [name=knowledgefactory1, salaray=1000.0]
Employee [name=knowledgefactory2, salaray=1200.0]
Employee [name=knowledgefactory1, salaray=1000.0]
Employee [name=knowledgefactory2, salaray=1200.0]
JSON array to List of objects
Employee [name=knowledgefactory1, salaray=1000.0]
Employee [name=knowledgefactory2, salaray=1200.0]
Alternative...
Employee [name=knowledgefactory1, salaray=1000.0]
Employee [name=knowledgefactory2, salaray=1200.0]
