From 927175ea20929675f5985a05ad32fb346462c3e5 Mon Sep 17 00:00:00 2001
From: taroplus <taroplus@users.noreply.github.com>
Date: Mon, 15 Nov 2021 11:16:45 -0800
Subject: [PATCH] [Java] lookup by byteArray is giving back wrong entry (#6915)

---
 java/com/google/flatbuffers/FlexBuffers.java | 14 +++++++++--
 tests/JavaTest.java                          | 25 ++++++++++++++++++++
 2 files changed, 37 insertions(+), 2 deletions(-)

diff --git a/java/com/google/flatbuffers/FlexBuffers.java b/java/com/google/flatbuffers/FlexBuffers.java
index b8f879b6e..75a0595f6 100644
--- a/java/com/google/flatbuffers/FlexBuffers.java
+++ b/java/com/google/flatbuffers/FlexBuffers.java
@@ -788,7 +788,12 @@ public class FlexBuffers {
                 if (io == other.length) {
                     // in our buffer we have an additional \0 byte
                     // but this does not exist in regular Java strings, so we return now
-                    return c1 - c2;
+                    int cmp = c1 - c2;
+                    if (cmp != 0 || bb.get(ia) == '\0') {
+                        return cmp;
+                    } else {
+                        return 1;
+                    }
                 }
             }
             while (c1 == c2);
@@ -961,7 +966,12 @@ public class FlexBuffers {
                 if (l2 == other.length) {
                     // in our buffer we have an additional \0 byte
                     // but this does not exist in regular Java strings, so we return now
-                    return c1 - c2;
+                    int cmp = c1 - c2;
+                    if (cmp != 0 || bb.get(l1) == '\0') {
+                        return cmp;
+                    } else {
+                        return 1;
+                    }
                 }
             }
             while (c1 == c2);
diff --git a/tests/JavaTest.java b/tests/JavaTest.java
index ce5751e83..0f2ad12da 100644
--- a/tests/JavaTest.java
+++ b/tests/JavaTest.java
@@ -1097,6 +1097,30 @@ class JavaTest {
         TestEq(m.get(key4).asString(), utf8keys[4]);
     }
 
+    public static void testFlexBuffersMapLookup() {
+        FlexBuffersBuilder builder = new FlexBuffersBuilder(ByteBuffer.allocate(512),
+                FlexBuffersBuilder.BUILDER_FLAG_SHARE_KEYS_AND_STRINGS);
+
+        String key0 = "123";
+        String key1 = "1234";
+        String key2 = "12345";
+        String[] keys = new String[]{key0, key1, key2};
+
+        int map = builder.startMap();
+
+        for (int i=0; i< keys.length; i++) {
+            builder.putString(keys[i], keys[i]);  // Testing key and string reuse.
+        }
+        builder.endMap(null, map);
+        builder.finish();
+
+        FlexBuffers.Map m = FlexBuffers.getRoot(builder.getBuffer()).asMap();
+        for (int i=0; i< keys.length; i++) {
+            TestEq(m.get(keys[i]).asString(), keys[i]);
+            TestEq(m.get(keys[i].getBytes(StandardCharsets.UTF_8)).asString(), keys[i]);
+        }
+    }
+
     public static void TestFlexBuffers() {
         testSingleElementByte();
         testSingleElementShort();
@@ -1121,6 +1145,7 @@ class JavaTest {
         testDeprecatedTypedVectorString();
         testBuilderGrowth();
         testFlexBuffersUtf8Map();
+        testFlexBuffersMapLookup();
     }
 
     static void TestVectorOfBytes() {