Unzip specific file from inputstream into another inputstream with same file name and type in java

I have an inputstream that contains a zip file, I need to extract a specific file from this zip file, and put the extracted file in an inputstream, with extracted file type and name.
Example: zip file in an inputstream, I need to unzip ".pdf" file, and put this ".pdf" file in an inputstream with the ".pdf" file name and type.

I tried the following flow:

private InputStream extractPdfFile(InputStream zipInputStream) {
        try {
            ZipInputStream zip = new ZipInputStream(zipInputStream);
            ZipEntry entry;
            while ((entry = zip.getNextEntry()) != null) {
                String currentFileName = entry.getName();
                if (currentFileName.endsWith(PP_FILE_EXTENTION)) {
                    ByteArrayOutputStream outputStream = new ByteArrayOutputStream();
                    byte[] buffer = new byte[2048];
                    int bytesRead;
                    while ((bytesRead = zip.read(buffer)) != -1) {
                        outputStream.write(buffer, 0, bytesRead);
                    }
                    zip.closeEntry();
                    zip.close();
                    outputStream.close();
                    return new ByteArrayInputStream(outputStream.toByteArray());
                }
                zip.closeEntry();
            }

            zip.close();
        } catch (IOException e) {
            e.printStackTrace();
        }
        return null; // File not found in the zip
    }

But it returns the new inputstream in zip format not .pdf.

Any idea how to unzip a file from inputstream and return the extracted file unzipped in another inputstream?

> I have an inputstream that contains a zip file

No you do not. Presumably you mean that you have an InputStream from which zip-formatted data can be read. This is not the same thing, and the distinction can be important.

> I need to extract a specific file from this zip file, and put the extracted file in an inputstream, with extracted file type and name.

And that's one of the ways in which it's important. The data in a stream do not have an associated filename. A stream is just a conduit for data. You may create a stream that provides content from a particular file, but that's not a recognizable characteristic of the stream itself. The type of the file's content is characteristic of the data, of course, but if by "file type" you mean "filename extension" or similar, then no, that just is not part of an InputStream.

A ZipInputStream in particular does support a higher level of abstraction over the content, so that you can read it as a sequence of ZipEntrys and their associated data, but that's a capability enabled by the specific form of the data (zip). There is no analogue for generic InputStreams.

> I tried the following flow: [...] But it returns the new inputstream in zip format not .pdf.

Implausible. The various ZipInputStream.read() methods read the uncompressed data of an entry. This is documented, and it has worked correctly for a very long time. You have implemented an approach that will successfully extract that uncompressed data, and will provide an InputStream from which that uncompressed data can then be read.

But again, there is no file name or extension associated with the stream that is returned. It's not even backed by a file. The stream just provides a sequence of bytes from an array. If you want to convey an associated filename then you need to do that separately. For example, perhaps you want to provide the ZipEntry describing the file, along with the InputStream from which the data can be read -- almost like ZipInputStream does itself.

You might, for example, bundle that together like so:

public class UncompressedData {
private byte[] bytes;
private String originalFilename;
private boolean isDirectory;
// ...
private UncompressedData() {
// empty
}
/**
* Creates and returns an UncompressedData object representing the
* current entry of the specified ZipInputStream, as described by
* the specified ZipEntry
*/
public static UncompressedData fromZip(ZipEntry entry, ZipInputStream stream)
throws MyUncompressedDataException {
UncompressedData data = new UncompressedData();
data.originalFilename = entry.getName();
data.isDirectory = entry.isDirectory();
if (data.isDirectory) {
data.bytes = new byte[0];
} else {
int numToRead = entry.getLength();
data.bytes = new byte[numToRead];
for (int offset = 0; offset < numToRead; ) {
int numRead = stream.read(data.bytes, offset, numToRead);
if (numRead < 1) {
throw new MyCompressedDataException();
}
offset += numRead;
numToRead -= numRead;
}
}
return data;
}
/**
* Creates and returns an InputStream from which the bytes of this
* UncompressedData can be read.
*/
public InputStream asStream() {
return new ByteArrayInputStream(bytes);
}
/**
* Returns a filename associated with this UncompressedData.
* Typically, this will be the name of an original source file from which
* the data were (somehow) obtained.
*/
public String getOriginalFilename() {
return originalFilename;
}
}