Create compress /zip file in java (ZipOutputStream class /example)

1. Given the input files in java, create zip or compress files using ZipOutputStream class .
2. Java framework has provided couple of classes to create a zip & compress file.
   • ZipOutputStream: ZipOutputStream class implements an output stream filter for writing files in ZIP file format.
   • ZipEntry: ZipEntry class represents a ZIP file entry.
     • e.g. If we want to zip file named “FirstFile.txt”, then ZipEntry of “FirstFile.txt” shall be created.

1. Create compressed/zip file in java (ZipOutputStream/example)

• Suppose, we would like to zip three files named “FirstFile.txt”, “SecondFile.txt” and “ThirdFile.txt”.
• We create output zip file using ZipOutputStream class.
• Let us zip input file “FirstFile.txt” in java.
  1. We would like to zip first file named “FirstFile.txt”.
  2. We will create ZipEntry having name “FirstFile.txt”.
  3. We will put the ZipEntry object to ZipOutputStream i.e. zipped content representing “FirstFile.txt”.
  4. We will read contents of “FirstFile.txt” and write to to ZipOutputStream.
  5. We have successfully zipped “FirstFile.txt”.
• Similarly, we can zip others file using ZipOutputStream in java.

2. Create compressed /zip file in java (ZipOutputStream /example)

package org.learn;

import java.io.File;
import java.io.FileInputStream;
import java.io.FileOutputStream;
import java.io.IOException;
import java.util.Arrays;
import java.util.List;
import java.util.zip.ZipEntry;
import java.util.zip.ZipOutputStream;

public class ZipFilesInJava {

    public static void main(String[] args) throws IOException {

        //Path of output zip file
        String outputZip = "C:\\ZipDirectory\\files.zip";

        //Contents to be zipped.
        List<File> files = Arrays.asList(
                new File("C:\\ZipDirectory\\FirstFile.txt"),
                new File("C:\\ZipDirectory\\SecondFile.txt"),
                new File("C:\\ZipDirectory\\ThirdFile.txt")
        );
        System.out.println("1. Zipping the contents of input directory");
        createZipFile(outputZip, files);
        System.out.println("2. Successfully zipped contents");


    }

    private static void createZipFile(String outputZip, List<File> listOfFiles)
            throws IOException {

        //Create zip file
        ZipOutputStream zipOutputStream = new ZipOutputStream(
                new FileOutputStream(outputZip));

        for (File file : listOfFiles) {

            String fileName = file.getName();

            //Read files
            FileInputStream readFile = new FileInputStream(file);

            //Create zip entry
            ZipEntry zipEntry = new ZipEntry(fileName);
            //Set zip entry
            zipOutputStream.putNextEntry(zipEntry);

            int readChar = -1;
            while ((readChar = readFile.read()) != -1) {
                zipOutputStream.write(readChar);
            }

            readFile.close();
            zipOutputStream.closeEntry();
            System.out.println("Zipping input file: "+fileName);
        }
        zipOutputStream.close();
    }
}

3. Example: Create of zip of input files in java

4. Output – Create compressed /zip file in java (ZipOutputStream /example)

1. Zipping the contents of input directory
Zipping input file: FirstFile.txt
Zipping input file: SecondFile.txt
Zipping input file: ThirdFile.txt
2. Successfully zipped contents