In this article, we are getting to extract the contents of the Java class file using the Apache Tika library. Apache Tika is employed for document type detection and content extraction from various file formats. It uses various document parsers and document type detection techniques to detect and extract data. It provides one generic API for parsing different file formats. of these parser libraries are encapsulated during a single interface called the Parser interface.

The following table shows a description of the important methods used in the solution : 

Example: Java code to extract the contents of Java class file format 

// Java program to extract the
// contents of Java class file
// format

import java.io.File;
import java.io.FileInputStream;
import java.io.IOException;

// importing Apache Tika libraries
import org.apache.tika.exception.TikaException;
import org.apache.tika.metadata.Metadata;
import org.apache.tika.parser.AutoDetectParser;
import org.apache.tika.parser.ParseContext;
import org.apache.tika.parser.Parser;
import org.apache.tika.sax.BodyContentHandler;

import org.xml.sax.SAXException;

public class ParserExtraction {

	public static void main(final String[] args)
		throws IOException, SAXException, TikaException
	{
		// create a File object
		File f = new File("AddTwoNumbers.java");

		// parse method parameters
		Parser parser = new AutoDetectParser();

		// instantiate BodyContentHandle
		BodyContentHandler handler
			= new BodyContentHandler();

		// Creates the Metadata object
		Metadata metadata = new Metadata();

		FileInputStream inputstream
			= new FileInputStream(f);

		// creates a parse context object
		ParseContext context = new ParseContext();

		// parsing the file
		parser.parse(inputstream, handler, metadata,
					context);
			
		// display the file content
		System.out.println("File content : "
						+ Handler.toString());
	}
}

// Java program to extract the
// contents of Java class file
// format

import java.io.File;
import java.io.FileInputStream;
import java.io.IOException;

// importing Apache Tika libraries
import org.apache.tika.exception.TikaException;
import org.apache.tika.metadata.Metadata;
import org.apache.tika.parser.AutoDetectParser;
import org.apache.tika.parser.ParseContext;
import org.apache.tika.parser.Parser;
import org.apache.tika.sax.BodyContentHandler;

import org.xml.sax.SAXException;

public class ParserExtraction {

	public static void main(final String[] args)
		throws IOException, SAXException, TikaException
	{
		// create a File object
		File f = new File("AddTwoNumbers.java");

		// parse method parameters
		Parser parser = new AutoDetectParser();

		// instantiate BodyContentHandle
		BodyContentHandler handler
			= new BodyContentHandler();

		// Creates the Metadata object
		Metadata metadata = new Metadata();

		FileInputStream inputstream
			= new FileInputStream(f);

		// creates a parse context object
		ParseContext context = new ParseContext();

		// parsing the file
		parser.parse(inputstream, handler, metadata,
					context);
			
		// display the file content
		System.out.println("File content : "
						+ Handler.toString());
	}
}