Google GSON is a simple Java-based serialization/deserialization library to convert Java Objects into their JSON representation. It can also be used to convert a JSON string to an equivalent Java Object. It is a reliable, fast, and efficient extension to the Java standard library. It’s also highly optimized. Assumes Java is already installed in your local environment.
Setting Up the Path for Linux
The environment variable PATH should be properly set. If you’ve trouble doing this refer to your particular shell documentation. For example: If you use bash as your shell, then you would add the following to the end our your ‘.bashrc’ file:
export PATH=$PATH:/path/to/java
Setting up the Path for Windows
Assumes you have properly installed Java in C:\Program Files\java\jdk-directory
Edit the ‘ C:\autoexec.bat’ file and add the following line at the end:
SET PATH=%PATH%:C:\Program Files\java\jdk\bin
Download GSON Archive
Download the latest GSON archive: https://search.maven.org/artifact/com.google.code.gson/gson/2.8.6/jar
(or)
Maven:
<dependency> <groupId>com.google.code.gson</groupId> <artifactId>gson</artifactId> <version>2.8.6</version> </dependency>
Set CLASSPATH Variable
Manually:
|
OS |
Output |
|---|---|
| Linux | export CLASSPATH=$CLASSPATH:$GSON_HOME/gson-2.8.6.jar:. |
| Windows |
Set the environment variable CLASSPATH to %CLASSPATH%;%GSON_HOME%\gson-2.8.6.jar;:; |
| Mac | export CLASSPATH=$CLASSPATH:$GSON_HOME/gson-2.8.6.jar:. |
With the help of IDE: In IntelliJ IDEA: Follow the below steps
Steps: Right Click on Project -> Open Module Settings -> Libraries -> Click + -> Add GSON Jar -> Apply and OK
GSON Application
Java
import java.io.*;import java.util.List; public class Staff { private String name; private int age; private int salary; private List<String> skillSet; public int getSalary() { return salary; } public void setSalary(int salary) { this.salary = salary; } public String getName() { return name; } public void setName(String name) { this.name = name; } public int getAge() { return age; } public void setAge(int age) { this.age = age; } public List<String> getSkillSet() { return skillSet; } public void setSkillSet(List<String> skillSet) { this.skillSet = skillSet; }} |
Java
import com.google.gson.Gson;import java.io.*;import java.io.FileWriter;import java.io.IOException;import java.util.Arrays;import java.util.List; public class GSONExample { public static void main(String[] args) { Gson gson = new Gson(); Staff staff = createStaffObj( "Anurag", 18, 100, Arrays.asList("DevOps", "Machine Learning", "Open Source")); // Java Object to String String json = gson.toJson(staff); // Java Object to a file try (FileWriter writer = new FileWriter( "/home/anurag/gsonexample.txt")) { gson.toJson(staff, writer); } catch (IOException e) { e.printStackTrace(); } } public static Staff createStaffObj(String name, int age, int salary, List<String> skillSet) { Staff staff = new Staff(); staff.setName(name); staff.setAge(age); staff.setSalary(salary); staff.setSkillSet(skillSet); return staff; }} |
By default, GSON writes JSON in compact mode.
{"name":"Anurag","age":18,"salary":100,"skillSet":["DevOps","Machine Learning","Open Source"]}
After enabling the pretty-print mode:
import com.google.gson.GsonBuilder;
import java.io.FileWriter;
import java.io.IOException;
import java.util.Arrays;
import java.util.List;
public class GSONExample {
public static void main(String[] args) {
Gson gson = new GsonBuilder().setPrettyPrinting().create();
...
...
...
}
}
{
"name": "Anurag",
"age": 18,
"salary": 100,
"skillSet": [
"DevOps",
"Machine Learning",
"Open Source"
]
}
Converting Java Object to JSON is comparatively easy than parsing with Gson streaming API. By default, JSONWriter writes JSON in compact form but we can set indent for pretty-printing.
