java.util.zip package provides facility of reading/writing zip files.

Example below lists files contained in zip file and reads first line of file.

 import java.io.*;
import java.util.zip.*;

class  readZipFiles 
{
    public static void main(String[] args) 
    {
         if (args.length != 1) 
        {
            System.out.println("Usage: java testFiles [zipfile path] ");
            return;
        }
        try
        {
            String filename = args[0];
            readZipFiles list = new readZipFiles( );
            list.readZipFiles(filename);
        }
        catch (Exception e)
        {
            e.printStackTrace();
        }
    }

    public void readZipFiles(String filename)
    {
        try
        {
            byte[] buf = new byte[1024];
            ZipInputStream zipinputstream = null;
            ZipEntry zipentry;
            zipinputstream = new ZipInputStream(
                 new FileInputStream(filename));

            zipentry = zipinputstream.getNextEntry();
            while (zipentry != null) 
            { 
                //for each entry to be extracted
                String entryName = zipentry.getName();
                System.out.println("File ::"+entryName);
                RandomAccessFile  rf;
                File newFile = new File(entryName);
                String directory = newFile.getParent();

                if(directory == null)
                {
                    if(newFile.isDirectory())
                        break;
                }

                rf = new RandomAccessFile(entryName,"r");               
                String line;

                if ((line =rf.readLine()) !=null)
                {
                    System.out.println(line);
                }

                rf.close(); 
                zipinputstream.closeEntry();
                zipentry = zipinputstream.getNextEntry();

            }//while

            zipinputstream.close();
        }
        catch (Exception e)
        {
            e.printStackTrace();
        }
    }
}