Which classes in Java support reading and writing streams in compressed format?

Java uses classes from the java.util.zip and java.util.jar packages for working with compressed streams.

Main classes:

• GZIPInputStream and GZIPOutputStream: For working with the GZIP format.
• ZipInputStream and ZipOutputStream: For working with the ZIP format.
• DeflaterInputStream and DeflaterOutputStream: Use the DEFLATE algorithm (the basis of GZIP and ZIP, but without metadata).

Example of reading GZIP:

import java.io.FileInputStream;
import java.io.IOException;
import java.util.zip.GZIPInputStream;

public class GzipReader {
    public static void main(String[] args) throws IOException {
        try (GZIPInputStream gis = new GZIPInputStream(new FileInputStream("file.gz"))) {
            int data = gis.read();
            while (data != -1) {
                // Processing read data
                System.out.print((char) data);
                data = gis.read();
            }
        }
    }
}

Example of writing to GZIP:

import java.io.FileOutputStream;
import java.io.IOException;
import java.util.zip.GZIPOutputStream;

public class GzipWriter {
    public static void main(String[] args) throws IOException {
        String content = "This is some data to be compressed.";
        try (GZIPOutputStream gos = new GZIPOutputStream(new FileOutputStream("file.gz"))) {
            gos.write(content.getBytes());
        }
    }
}

Similar principles apply to ZipInputStream and ZipOutputStream classes, but they work with entries inside ZIP archives.

These classes are wrappers over regular input/output streams (InputStream, OutputStream) and automatically perform compression/decompression.