Assignments are not expressions, and only expressions are allowed in this context - Error when convert Java to Kotlin

I have well managed code and project in Java. But I need to develop another project from it in Kotlin. So, I converted all code as possible in Kotlin. But there is code of ZipFileManager.kt which is use to zip/unzip files.

Here is code(Kotlin):

object ZipFileManager {

    private val BUFFER_SIZE = 6 * 1024

    @Throws(IOException::class)
    fun zip(files: Array<String>, zipFile: String) {
        var origin: BufferedInputStream? = null
        val out = ZipOutputStream(BufferedOutputStream(FileOutputStream(zipFile)))
        try {
            val data = ByteArray(BUFFER_SIZE)

            for (file in files) {
                val fi = FileInputStream(file)
                origin = BufferedInputStream(fi, BUFFER_SIZE)
                try {
                    val entry = ZipEntry(file.substring(file.lastIndexOf("/") + 1))
                    out.putNextEntry(entry)
                    var count: Int
                    while ((count = origin.read(data, 0, BUFFER_SIZE)) != -1)     {
                        out.write(data, 0, count)
                    }
                } finally {
                    origin.close()
                }
            }
        } finally {
            out.close()
        }
    }

    fun unzip(zipFileUrl: String, fileLocation: String) {
        try {
            val f = File(fileLocation)
            if (!f.isDirectory) {
                f.mkdirs()
            }
            ZipInputStream(FileInputStream(zipFileUrl)).use { zin ->
                var ze: ZipEntry? = null
                while ((ze = zin.nextEntry) != null) {
                    //                    Log.e("UnZipFILE", "Unzipping....");
                    val path = fileLocation + ze!!.name

                    if (ze.isDirectory) {
                        val unzipFile = File(path)
                        if (!unzipFile.isDirectory) {
                            unzipFile.mkdirs()
                        }
                    } else {
                        FileOutputStream(path, false).use { fout ->
                            val buffer = ByteArray(1024)
                            var read: Int
                            while ((read = zin.read(buffer)) != -1) {
                                fout.write(buffer, 0, read)
                            }
                            zin.closeEntry()
                        }
                    }
                }
            }
        } catch (e: Exception) {
            e.printStackTrace()
            Log.e("UnZipException", Log.getStackTraceString(e))
        }

    }
}

So, I am trying through this code but It's shows compile time error like:

Assignments are not expressions, and only expressions are allowed in this context in the fun zip at the line while ((count = origin.read(data, 0, BUFFER_SIZE)) != -1)

and give another same compile time error at line while ((ze = zin.nextEntry) != null) and at the line while ((read = zin.read(buffer)) != -1).

So, my big problem is to use this code in Kotlin. So, any body can help who have knowledge of Kotlin and how can I use this type of looping structure in Kotlin?

There is also I have Java code if any body want to see:

public class ZipFileManager {

    private static int BUFFER_SIZE = 6 * 1024;

    public static void zip(String[] files, String zipFile) throws IOException {
        BufferedInputStream origin = null;
        ZipOutputStream out = new ZipOutputStream(new BufferedOutputStream(new FileOutputStream(zipFile)));
        try {
            byte data[] = new byte[BUFFER_SIZE];

            for (String file : files) {
                FileInputStream fi = new FileInputStream(file);
                origin = new BufferedInputStream(fi, BUFFER_SIZE);
                try {
                    ZipEntry entry = new ZipEntry(file.substring(file.lastIndexOf("/") + 1));
                    out.putNextEntry(entry);
                    int count;
                    while ((count = origin.read(data, 0, BUFFER_SIZE)) != -1) {
                        out.write(data, 0, count);
                    }
                } finally {
                    origin.close();
                }
            }
        } finally {
            out.close();
        }
    }

    public static void unzip(String zipFileUrl, String fileLocation) {
        try {
            File f = new File(fileLocation);
            if (!f.isDirectory()) {
                f.mkdirs();
            }
            try (ZipInputStream zin = new ZipInputStream(new FileInputStream(zipFileUrl))) {
                ZipEntry ze = null;
                while ((ze = zin.getNextEntry()) != null) {
//                    Log.e("UnZipFILE", "Unzipping....");
                    String path = fileLocation + ze.getName();

                    if (ze.isDirectory()) {
                        File unzipFile = new File(path);
                        if (!unzipFile.isDirectory()) {
                            unzipFile.mkdirs();
                        }
                    } else {
                        try (FileOutputStream fout = new FileOutputStream(path, false)) {
                            byte[] buffer = new byte[1024];
                            int read;
                            while ((read = zin.read(buffer)) != -1) {
                                fout.write(buffer, 0, read);
                            }
                            zin.closeEntry();
                        }
                    }
                }
            }
        } catch (Exception e) {
            e.printStackTrace();
            Log.e("UnZipException", Log.getStackTraceString(e));
        }
    }
}

I also try to manage loop like:

do {
    ze = zin.nextEntry
} while (ze != null)

But than file is not got unzip properly or its broken. So, if any body have idea of managing this type of loop than it will very helpful.