Jackson provide api’s to convert JSON data to Collections Objects like Map, ArrayList etc.
In below example file student_data.txt having collections of students data in JSON form and through these Jacson API’s will convert JSON data to ArrayList java object.
Pre-Requisite
Add below jackson-databind-2.8.5.jar in your classpath or make dependency entry in pom.xml file.
<dependency>
<groupId>com.fasterxml.jackson.core</groupId>
<artifactId>jackson-databind</artifactId>
<version>2.8.5</version>
</dependency>
Sample Data
Add below content in student_data.txt
[
{
"rollNumber" : 11,
"firstName" : "Saurabh",
"lastName" : "Gupta",
"permanent" : false,
"address" : {
"addressLine" : "Lake Union Hill Way",
"city" : "Atlanta",
"zipCode" : 50005
},
"phoneNumbers" : [ 2233445566, 3344556677 ],
"cities" : [ "Dallas", "San Antonio", "Irving" ],
"properties" : {
"play" : "Badminton",
"interst" : "Math",
"age" : "34 years"
}
},
{
"rollNumber" : 11,
"firstName" : "Gaurav",
"lastName" : "Khaira",
"permanent" : true,
"address" : {
"addressLine" : " 5770 Shiloh woods dr",
"city" : "Cumming",
"zipCode" : 50007
},
"phoneNumbers" : [ 2233445567, 3344556678 ],
"cities" : [ "New York", "Austin", "Plano" ],
"properties" : {
"play" : "Baseball",
"interst" : "Science",
"age" : "36 years"
}
}
]
Example
package test.facingissesonit.json.jacson;
import java.io.IOException;
import java.nio.file.Files;
import java.nio.file.Paths;
import java.util.Arrays;
import java.util.List;
import com.fasterxml.jackson.databind.JsonMappingException;
import com.fasterxml.jackson.databind.ObjectMapper;
public class ConvertJsonToArrayList {
public static void main(String[] args) {
try
{
byte[] mapData = Files.readAllBytes(Paths.get("student_data.txt"));
Student[] studentArr = null;
ObjectMapper objectMapper = new ObjectMapper();
studentArr = objectMapper.readValue(mapData, Student[].class);
List<Student> studentList=Arrays.asList(studentArr);
System.out.println("Student 1 \n"+studentList.get(0));
System.out.println("Student 2 \n"+studentList.get(1));
}
catch(JsonMappingException ex)
{
ex.printStackTrace();
}
catch(IOException ex)
{
ex.printStackTrace();
}
}
}
Model Classes
Below Student and Address are required classes for execute this code.
package test.facingissesonit.json.jacson;
import java.util.Arrays;
import java.util.List;
import java.util.Map;
public class Student {
private int rollNumber;
private String firstName;
private String lastName;
private boolean permanent;
private Address address;
private long[] phoneNumbers;
private List<String> cities;
private Map<String, String> properties;
@Override
public String toString()
{
StringBuffer sb=new StringBuffer();
sb.append("==============Student Information================\n");
sb.append("rollNumber=").append(rollNumber).append("\n");
sb.append("firstName=").append(firstName).append("\n");
sb.append("lastName=").append(lastName).append("\n");
sb.append("permanent=").append(permanent).append("\n");
sb.append("adress=").append(address).append("\n");
sb.append("phoneNumbers=").append(Arrays.toString(phoneNumbers)).append("\n");
sb.append("cities=").append(Arrays.toString(cities.toArray(new String[cities.size()]))).append("\n");
sb.append("properties=").append(properties).append("\n");
return sb.toString();
}
public int getRollNumber() {
return rollNumber;
}
public void setRollNumber(int rollNumber) {
this.rollNumber = rollNumber;
}
public String getFirstName() {
return firstName;
}
public void setFirstName(String firstName) {
this.firstName = firstName;
}
public String getLastName() {
return lastName;
}
public void setLastName(String lastName) {
this.lastName = lastName;
}
public boolean isPermanent() {
return permanent;
}
public void setPermanent(boolean permanent) {
this.permanent = permanent;
}
public Address getAddress() {
return address;
}
public void setAddress(Address address) {
this.address = address;
}
public long[] getPhoneNumbers() {
return phoneNumbers;
}
public void setPhoneNumbers(long[] phoneNumbers) {
this.phoneNumbers = phoneNumbers;
}
public List<String> getCities() {
return cities;
}
public void setCities(List<String> cities) {
this.cities = cities;
}
public Map<String, String> getProperties() {
return properties;
}
public void setProperties(Map<String, String> properties) {
this.properties = properties;
}
}
package test.facingissesonit.json.jacson;
public class Address {
private String addressLine;
private String city;
private String state;
private int zipCode;
@Override
public String toString()
{
StringBuffer sb=new StringBuffer();
sb.append("AddressLine=").append(addressLine).append("\n");
sb.append("city=").append(city).append("\n");
sb.append("state=").append(state).append("\n");
sb.append("zipCode=").append(zipCode).append("\n");
return sb.toString();
}
public String getAddressLine() {
return addressLine;
}
public void setAddressLine(String addressLine) {
this.addressLine = addressLine;
}
public String getCity() {
return city;
}
public void setCity(String city) {
this.city = city;
}
public String getState() {
return state;
}
public void setState(String state) {
this.state = state;
}
public int getZipCode() {
return zipCode;
}
public void setZipCode(int zipCode) {
this.zipCode = zipCode;
}
}
Output
Below is console output generated by program which is from Java Object.
Student 1
==============Student Information================
rollNumber=11
firstName=Saurabh
lastName=Gupta
permanent=false
adress=AddressLine=Lake Union Hill Way
city=Atlanta
state=null
zipCode=50005
phoneNumbers=[2233445566, 3344556677]
cities=[Dallas, San Antonio, Irving]
properties={play=Badminton, interst=Math, age=34 years}
Student 2
==============Student Information================
rollNumber=11
firstName=Gaurav
lastName=Khaira
permanent=true
adress=AddressLine= 5770 Shiloh woods dr
city=Cumming
state=null
zipCode=50007
phoneNumbers=[2233445567, 3344556678]
cities=[New York, Austin, Plano]
properties={play=Baseball, interst=Science, age=36 years}
More Sample Code
For more java and JDBC codes follow below links
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