Compile-time JSON-parser

generates a JSON-parser for Java-objects at compile-time

Compile-time JSON-parser supports both non-private variables and properties.

The generated JSON-parser uses org.json:json.

Setup

• Download and install Maven
• Download the sources
• Run mvn clean install in the directory of Compile-time JSON-parser
• Create a Maven Project in IntelliJ where you want to use Compile-time JSON-parser
• Add the following dependency to the pom.xml of the project where you want to use Compile-time JSON-parser (replace VERSION with the version from )

<dependency>
    <groupId>io.github.danthe1st</groupId>
    <artifactId>compile-time-json-parser</artifactId>
    <version>VERSION</version>
</dependency>

• If you wish to use JPMS, also add the annotation processor to the maven-compiler-plugin

<plugin>
	<artifactId>maven-compiler-plugin</artifactId>
	<version>3.8.1</version>
	<configuration>
		<release>11</release>
		<annotationProcessorPaths>
			<annotationProcessorPath>
				<groupId>io.github.danthe1st</groupId>
				<artifactId>compile-time-json-parser</artifactId>
				<version>VERSION</version>
			</annotationProcessorPath>
		</annotationProcessorPaths>
	</configuration>
</plugin>

• Enable annotation processing for this project under Settings>Build, Execution, Deployment>Compiler>Annotation Processors>Enable Annotation Processing

Usage

• Create a data class and annotate it with @GenerateJSON like this:

import io.github.danthe1st.json_compile.api.GenerateJSON;
@GenerateJSON
public class TestClass {
  public int someInt;
  private String someString;
  private int[][] someArray;

  public String getSomeString() {
    return someString;
  }

  public void setSomeString(String someString) {
    this.someString = someString;
  }

  public int[][] getSomeArray() {
    return someArray;
  }

  public void setSomeArray(int[][] someArray) {
    this.someArray = someArray;
  }
  
  @Override
  public String toString() {
    return "TestClass{" +
            "someInt=" + someInt +
            ", someString='" + someString + '\'' +
            ", someArray=" + Arrays.deepToString(someArray) +
            '}';
  }
}

• When compiling the class, a class suffixed with JSONLoader should be automatically generated.
  This class contains a method named fromJSON that creates an instance of the data class from a String:

String json= String.join("", Files.readAllLines(Path.of("testClass.json")));
TestClass obj = TestClassJSONLoader.fromJSON(json);
System.out.println(obj);
TestClass testObj=new TestClass();
testObj.setSomeString("test");
testObj.someInt=12345;
testObj.someArray=new int[][]{{1,2,3},{},null,{1,2,3,4,5,6}};
System.out.println(TestClassJSONLoader.toJSON(testObj));

Example

An example project can be found in the directory examples/maven-example.

• Import Compile-time JSON-parser in IntelliJ as a maven project
• Run mvn clean install in that project
• Expand the examples/maven-example directory
• Right-click on the file pom.xml in that directory and select Add as a Maven Project
• Make sure you set up your IDE correctly
• Run TestClass in examples/maven-example/src/main/java/io/github/danthe1st/json_compile/test/TestClass

Supported types

• String
• int
• long
• float
• double
• boolean
• Enums
• Wrapper classes for supported primitive types
• Objects of classes annotated with @GenerateJSON
• Collections if they are not part of other collections or arrays, Collections of classes annotated with @GenerateJSON that contain collections are supported, however
• Arrays
• org.json.JSONObject and org.json.JSONArray

Limitations

• It is not possible to create an array/collection of collections
• Objects annotated with @GenerateJSON need to have a no-args-constructor
• Collections need to be initialized in the constructor
• Generic objects are not supported (except generic collections)
• Configuration is not supported

IDE-specific configuration

Eclipse

• Install the m2e-apt plugin

• Right-click the project, open Properties>Java Compiler>Annotation Processing> and select Enable Project Specific Settings and Enable processing in Editor

IntelliJ

• Enable annotation processing for this project under Settings>Build, Execution, Deployment>Compiler>Annotation Processors>Maven default annotation processors profile>json-parser-maven-example>Enable Annotation Processing