--- old/src/java.base/share/classes/java/nio/Buffer.java	2019-12-09 18:15:06.403579131 +0000
+++ new/src/java.base/share/classes/java/nio/Buffer.java	2019-12-09 18:15:05.947571050 +0000
@@ -28,7 +28,9 @@
 import jdk.internal.HotSpotIntrinsicCandidate;
 import jdk.internal.access.JavaNioAccess;
 import jdk.internal.access.SharedSecrets;
+import jdk.internal.access.foreign.MemorySegmentProxy;
 import jdk.internal.misc.Unsafe;
+import jdk.internal.vm.annotation.ForceInline;
 
 import java.util.Spliterator;
 
@@ -213,13 +215,26 @@
     // NOTE: hoisted here for speed in JNI GetDirectBufferAddress
     long address;
 
+    // Used by buffers generated by the memory access API (JEP-370)
+    final MemorySegmentProxy segment;
+
+
+    // Creates a new buffer with given address and capacity.
+    //
+    Buffer(long addr, int cap, MemorySegmentProxy segment) {
+        this.address = addr;
+        this.capacity = cap;
+        this.segment = segment;
+    }
+
     // Creates a new buffer with the given mark, position, limit, and capacity,
     // after checking invariants.
     //
-    Buffer(int mark, int pos, int lim, int cap) {       // package-private
+    Buffer(int mark, int pos, int lim, int cap, MemorySegmentProxy segment) {       // package-private
         if (cap < 0)
             throw createCapacityException(cap);
         this.capacity = cap;
+        this.segment = segment;
         limit(lim);
         position(pos);
         if (mark >= 0) {
@@ -731,6 +746,13 @@
         mark = -1;
     }
 
+    @ForceInline
+    final void checkSegment() {
+        if (segment != null) {
+            segment.checkValidState();
+        }
+    }
+
     static {
         // setup access to this package in SharedSecrets
         SharedSecrets.setJavaNioAccess(
@@ -739,6 +761,31 @@
                 public JavaNioAccess.BufferPool getDirectBufferPool() {
                     return Bits.BUFFER_POOL;
                 }
+
+                @Override
+                public ByteBuffer newDirectByteBuffer(long addr, int cap, Object obj, MemorySegmentProxy segment) {
+                    return new DirectByteBuffer(addr, cap, obj, segment);
+                }
+
+                @Override
+                public ByteBuffer newHeapByteBuffer(byte[] hb, int offset, int capacity, MemorySegmentProxy segment) {
+                    return new HeapByteBuffer(hb, offset, capacity, segment);
+                }
+
+                @Override
+                public Object getBufferBase(ByteBuffer bb) {
+                    return bb.base();
+                }
+
+                @Override
+                public long getBufferAddress(ByteBuffer bb) {
+                    return bb.address;
+                }
+
+                @Override
+                public void checkSegment(Buffer buffer) {
+                    buffer.checkSegment();
+                }
             });
     }