Few Jackson examples to convert a JSON array string to a List
// JSON array string
// [{"name":"favtuts", "age":37}, {"name":"fong", "age":38}]
ObjectMapper mapper = new ObjectMapper();
String json = "[{\"name\":\"favtuts\", \"age\":37}, {\"name\":\"fong\", \"age\":38}]";
// 1. convert JSON array to Array objects
Person[] pp1 = mapper.readValue(json, Person[].class);
// 2. convert JSON array to List of objects
List<Person> ppl2 = Arrays.asList(mapper.readValue(json, Person[].class));
pom.xml
<dependency> <groupId>com.fasterxml.jackson.core</groupId> <artifactId>jackson-databind</artifactId> <version>2.9.8</version> </dependency>
P.S Tested with Jackson 2.9.8
1. Convert JSON array string to List
1.1 JSON array string
[{"name":"favtuts", "age":37}, {"name":"fong", "age":38}]1.2 Create an object to map the above JSON fields.
package com.favtuts.json.jsonarray;
public class Person {
public Person(String name, Integer age) {
this.name = name;
this.age = age;
}
public Person() {
}
String name;
Integer age;
//getters and setters
public String getName() {
return this.name;
}
public void setName(String name) {
this.name = name;
}
public Integer getAge() {
return this.age;
}
public void setAge(Integer age) {
this.age = age;
}
@Override
public String toString() {
return "Person{" +
" name='" + getName() + "'" +
", age='" + getAge() + "'" +
"}";
}
}
1.3 Convert the JSON array string to a List
JacksonArrayExample.java
package com.favtuts.json;
import java.io.IOException;
import java.util.Arrays;
import java.util.List;
import com.fasterxml.jackson.core.type.TypeReference;
import com.fasterxml.jackson.databind.ObjectMapper;
import com.favtuts.json.jsonarray.Person;
public class JacksonArrayExample {
public static void main(String[] args) {
convertJSONarrayToList();
}
static void convertJSONarrayToList() {
ObjectMapper mapper = new ObjectMapper();
String json = "[{\"name\":\"favtuts\", \"age\":37}, {\"name\":\"fong\", \"age\":38}]";
try {
// 1. convert JSON array to Array objects
Person[] pp1 = mapper.readValue(json, Person[].class);
System.out.println("JSON array to Array objects...");
for (Person person : pp1) {
System.out.println(person);
}
// 2. convert JSON array to List of objects
List<Person> ppl2 = Arrays.asList(mapper.readValue(json, Person[].class));
System.out.println("\nJSON array to List of objects");
ppl2.stream().forEach(x -> System.out.println(x));
// 3. alternative
List<Person> pp3 = mapper.readValue(json, new TypeReference<List<Person>>() {
});
System.out.println("\nAlternative...");
pp3.stream().forEach(x -> System.out.println(x));
} catch (IOException e) {
e.printStackTrace();
}
}
}
Output
JSON array to Array objects...
Person{ name='favtuts', age='37'}
Person{ name='fong', age='38'}
JSON array to List of objects
Person{ name='favtuts', age='37'}
Person{ name='fong', age='38'}
Alternative...
Person{ name='favtuts', age='37'}
Person{ name='fong', age='38'}Download Source Code
$ git clone https://github.com/favtuts/java-core-tutorials-examples
$ cd java-basic/json