--- a/src/jdk.zipfs/share/classes/jdk/nio/zipfs/ZipFileSystem.java	Thu Aug 22 09:53:19 2019 -0400
+++ b/src/jdk.zipfs/share/classes/jdk/nio/zipfs/ZipFileSystem.java	Thu Aug 22 10:43:25 2019 -0400
@@ -1458,7 +1458,7 @@
             return 0;
 
         long written = 0;
-        if (e.csize > 0 && (e.crc != 0 || e.size == 0)) {
+        if (e.method != METHOD_STORED && e.csize > 0 && (e.crc != 0 || e.size == 0)) {
             // pre-compressed entry, write directly to output stream
             writeTo(e, os);
         } else {

--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/test/jdk/jdk/nio/zipfs/UpdateEntryTest.java	Thu Aug 22 10:43:25 2019 -0400
@@ -0,0 +1,210 @@
+/*
+ * Copyright (c) 2019, Oracle and/or its affiliates. All rights reserved.
+ * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
+ *
+ * This code is free software; you can redistribute it and/or modify it
+ * under the terms of the GNU General Public License version 2 only, as
+ * published by the Free Software Foundation.
+ *
+ * This code is distributed in the hope that it will be useful, but WITHOUT
+ * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
+ * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License
+ * version 2 for more details (a copy is included in the LICENSE file that
+ * accompanied this code).
+ *
+ * You should have received a copy of the GNU General Public License version
+ * 2 along with this work; if not, write to the Free Software Foundation,
+ * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
+ *
+ * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
+ * or visit www.oracle.com if you need additional information or have any
+ * questions.
+ *
+ */
+
+import org.testng.annotations.Test;
+
+import java.io.IOException;
+import java.io.InputStream;
+import java.io.OutputStream;
+import java.nio.charset.StandardCharsets;
+import java.nio.file.FileSystem;
+import java.nio.file.FileSystems;
+import java.nio.file.Files;
+import java.nio.file.Path;
+import java.util.Arrays;
+import java.util.spi.ToolProvider;
+import java.util.zip.CRC32;
+import java.util.zip.ZipEntry;
+import java.util.zip.ZipFile;
+import java.util.zip.ZipOutputStream;
+
+import static org.testng.Assert.*;
+
+/**
+ * @test
+ * @bug 8229887
+ * @summary Validate ZIP FileSystem can replace existing STORED and DEFLATED entries
+ * @modules jdk.zipfs
+ * @run testng UpdateEntryTest
+ */
+@Test
+public class UpdateEntryTest {
+
+    private static final Path HERE = Path.of(".");
+
+    // Use the ToolProvider interface for accessing the jar tool
+    private static final ToolProvider JAR_TOOL = ToolProvider.findFirst("jar")
+            .orElseThrow(() -> new RuntimeException("jar tool not found")
+            );
+
+    /**
+     * Represents an entry in a ZIP file. An entry encapsulates a name, a
+     * compression method, and its contents/data.
+     */
+    static class Entry {
+        private final String name;
+        private final int method;
+        private final byte[] bytes;
+
+        Entry(String name, int method, String contents) {
+            this.name = name;
+            this.method = method;
+            this.bytes = contents.getBytes(StandardCharsets.UTF_8);
+        }
+
+        static Entry of(String name, int method, String contents) {
+            return new Entry(name, method, contents);
+        }
+
+        /**
+         * Returns a new Entry with the same name and compression method as this
+         * Entry but with the given content.
+         */
+        Entry content(String contents) {
+            return new Entry(name, method, contents);
+        }
+
+        /**
+         * Writes this entry to the given ZIP output stream.
+         */
+        ZipEntry put(ZipOutputStream zos) throws IOException {
+            ZipEntry e = new ZipEntry(name);
+            e.setMethod(method);
+            e.setTime(System.currentTimeMillis());
+            if (method == ZipEntry.STORED) {
+                var crc = new CRC32();
+                crc.update(bytes);
+                e.setCrc(crc.getValue());
+                e.setSize(bytes.length);
+            }
+            zos.putNextEntry(e);
+            zos.write(bytes);
+            return e;
+        }
+    }
+
+    /**
+     * Validate that you can replace an existing entry in a JAR file that
+     * was added with the STORED(no-compression) option
+     */
+    public void testReplaceStoredEntry() throws IOException {
+        String jarFileName = "updateStoredEntry.jar";
+        String storedFileName = "storedFile.txt";
+        String replacedValue = "bar";
+        Path zipFile = Path.of(jarFileName);
+
+        // Create JAR file with a STORED(non-compressed) entry
+        Files.writeString(Path.of(storedFileName), "foobar");
+        int rc = JAR_TOOL.run(System.out, System.err,
+                "cM0vf", jarFileName, storedFileName);
+
+        // Replace the STORED entry
+        try (FileSystem fs = FileSystems.newFileSystem(zipFile)) {
+            Files.writeString(fs.getPath(storedFileName), replacedValue);
+        }
+        Entry e1 = Entry.of(storedFileName, ZipEntry.STORED, replacedValue);
+        verify(zipFile, e1);
+    }
+
+    /**
+     * Test updating an entry that is STORED (not compressed)
+     */
+    public void test1() throws IOException {
+        Entry e1 = Entry.of("foo", ZipEntry.STORED, "hello");
+        Entry e2 = Entry.of("bar", ZipEntry.STORED, "world");
+        test(e1, e2);
+    }
+
+    /**
+     * Test updating an entry that is DEFLATED (compressed)
+     */
+    public void test2() throws IOException {
+        Entry e1 = Entry.of("foo", ZipEntry.DEFLATED, "hello");
+        Entry e2 = Entry.of("bar", ZipEntry.STORED, "world");
+        test(e1, e2);
+    }
+
+    private void test(Entry e1, Entry e2) throws IOException {
+        Path zipfile = Files.createTempFile(HERE, "test", "zip");
+
+        // create zip file
+        try (OutputStream out = Files.newOutputStream(zipfile);
+             ZipOutputStream zos = new ZipOutputStream(out)) {
+            e1.put(zos);
+            e2.put(zos);
+        }
+
+        verify(zipfile, e1, e2);
+
+        String newContents = "hi";
+
+        // replace contents of e1
+        try (FileSystem fs = FileSystems.newFileSystem(zipfile)) {
+            Path foo = fs.getPath(e1.name);
+            Files.writeString(foo, newContents);
+        }
+
+        verify(zipfile, e1.content(newContents), e2);
+    }
+
+
+    /**
+     * Verify that the given path is a zip files containing exactly the
+     * given entries.
+     */
+    private static void verify(Path zipfile, Entry... entries) throws IOException {
+        // check entries with zip API
+        try (ZipFile zf = new ZipFile(zipfile.toFile())) {
+            // check entry count
+            assertTrue(zf.size() == entries.length);
+
+            // check compression method and content of each entry
+            for (Entry e : entries) {
+                ZipEntry ze = zf.getEntry(e.name);
+                assertTrue(ze != null);
+                assertTrue(ze.getMethod() == e.method);
+                try (InputStream in = zf.getInputStream(ze)) {
+                    byte[] bytes = in.readAllBytes();
+                    assertTrue(Arrays.equals(bytes, e.bytes));
+                }
+            }
+        }
+
+        // check entries with FileSystem API
+        try (FileSystem fs = FileSystems.newFileSystem(zipfile)) {
+            // check entry count
+            Path top = fs.getPath("/");
+            long count = Files.find(top, Integer.MAX_VALUE,
+                    (path, attrs) -> attrs.isRegularFile()).count();
+            assertTrue(count == entries.length);
+
+            // check content of each entry
+            for (Entry e : entries) {
+                Path file = fs.getPath(e.name);
+                byte[] bytes = Files.readAllBytes(file);
+                assertTrue(Arrays.equals(bytes, e.bytes));
+            }
+        }
+    }
+}