Java Program, JSON

How to Convert JSON to Java Object and Java Object to JSON?

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In below java codes consider both the cases from JSON to Java Object and Java Object to JSON by ObjectMapper by Jacson API’s

I have given generic method for both the cases as convertJavaObjectToJSON and convertJSONToJavaObject.

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>

JAVA and JSON Conversion Example:

Below is complete example for conversion of both the cases.

ObjectMapper.readValue() :Convert JSON String to Java Object

ObjectMapper.writeValue() : Convert JAVA Object to JSON

package test.facingissesonit.json.jacson;

import java.io.IOException;
import java.io.StringWriter;
import java.util.ArrayList;
import java.util.HashMap;
import java.util.List;
import java.util.Map;

import com.fasterxml.jackson.core.JsonGenerationException;
import com.fasterxml.jackson.databind.JsonMappingException;
import com.fasterxml.jackson.databind.ObjectMapper;
import com.fasterxml.jackson.databind.SerializationFeature;

public class JsonAndJavaObjectConversion {

public static void main(String[] args) {
System.out.println("=================Convert Student Java Object to JSON==============");
// convert Object to json string
Student student = sampleStudentObject();

String studentStr = convertJavaObjectToJSON(student);
System.out.println("Student JSON Data \n" + studentStr);
System.out.println("=================Convert JSON DATA  to Student JAVA Object==============");
Object object = convertJSONToJavaObject(studentStr, Student.class);
if (object != null && object instanceof Student) {
System.out.println("Student Object\n" + (Student) object);
}

}
//Generic Method to convert JSON object to Java Object
public static Object convertJSONToJavaObject(String strJsonData, Class className) {
try {
// ObjectMapper new instance
ObjectMapper objectMapper = new ObjectMapper();
// //convert json data from file text to object
return objectMapper.readValue(strJsonData, className);
} catch (JsonMappingException ex) {
ex.printStackTrace();
} catch (JsonGenerationException ex) {
ex.printStackTrace();
} catch (IOException ex) {
ex.printStackTrace();
}
return null;
}
//Generic Method to convert Java object to JSON
public static String convertJavaObjectToJSON(Object javaObject) {
StringWriter jsonStr = null;
try {

// ObjectMapper new instance
ObjectMapper objectMapper = new ObjectMapper();
// configure Object mapper for pretty print
objectMapper.configure(SerializationFeature.INDENT_OUTPUT, true);

// writing to console, can write to any output stream such as file
jsonStr = new StringWriter();
objectMapper.writeValue(jsonStr, javaObject);

} catch (JsonMappingException ex) {
ex.printStackTrace();
} catch (JsonGenerationException ex) {
ex.printStackTrace();
} catch (IOException ex) {
ex.printStackTrace();
}
return jsonStr.toString();
}

public static Student sampleStudentObject() {

Student student = new Student();
student.setRollNumber(11);
student.setFirstName("Saurabh");
student.setLastName("Gupta");
student.setPhoneNumbers(new long[] { 2233445566L, 3344556677L });

Address add = new Address();
add.setAddressLine("Lake Union Hill Way");
add.setCity("Atlanta");
add.setState("GA");
add.setZipCode(50005);
student.setAddress(add);

List<String> cities = new ArrayList<String>();
cities.add("Dallas");
cities.add("San Antonio");
cities.add("Irving");
student.setCities(cities);

Map<String, String> props = new HashMap<String, String>();
props.put("age", "34 years");
props.put("interst", "Math");
props.put("play", "Badminton");

student.setProperties(props);

return student;
}

}

Model Classes :

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:

=================Convert Student Java Object to JSON==============
Student JSON Data
{
"rollNumber" : 11,
"firstName" : "Saurabh",
"lastName" : "Gupta",
"permanent" : false,
"address" : {
"addressLine" : "Lake Union Hill Way",
"city" : "Atlanta",
"state" : "GA",
"zipCode" : 50005
},
"phoneNumbers" : [ 2233445566, 3344556677 ],
"cities" : [ "Dallas", "San Antonio", "Irving" ],
"properties" : {
"play" : "Badminton",
"interst" : "Math",
"age" : "34 years"
}
}
=================Convert JSON DATA  to Student JAVA Object==============
Student Object
==============Student Information================
rollNumber=11
firstName=Saurabh
lastName=Gupta
permanent=false
adress=AddressLine=Lake Union Hill Way
city=Atlanta
state=GA
zipCode=50005

phoneNumbers=[2233445566, 3344556677]
cities=[Dallas, San Antonio, Irving]
properties={play=Badminton, interst=Math, age=34 years}

More Sample Code

For more java and JDBC codes follow below links