diff --git a/jre_emul/Classes/com/google/j2objc/util/ReflectionUtil.java b/jre_emul/Classes/com/google/j2objc/util/ReflectionUtil.java
index 7f6b4832ec..fe2652a431 100644
--- a/jre_emul/Classes/com/google/j2objc/util/ReflectionUtil.java
+++ b/jre_emul/Classes/com/google/j2objc/util/ReflectionUtil.java
@@ -66,4 +66,12 @@ public static boolean isJreReflectionStripped() {
     // For more details about this behavior see {@link #matchClassNamePrefix}.
     return Boolean.TRUE.getClass().getName().equals("JavaLangBoolean");
   }
+
+  /**
+   * Checks if the given object is a NSNumber originating from ObjC by checking that it doesn't have
+   * class metadata. We use this for cross-language equality support, primarily for hashtable keys.
+   */
+  public static native boolean isObjCNumber(Object obj) /*-[
+    return [obj isKindOfClass:[NSNumber class]] && [[obj java_getClass] getMetadata] == NULL;
+  ]-*/;
 }
diff --git a/jre_emul/android/platform/libcore/harmony-tests/src/test/java/org/apache/harmony/tests/java/lang/ByteTest.java b/jre_emul/android/platform/libcore/harmony-tests/src/test/java/org/apache/harmony/tests/java/lang/ByteTest.java
index bbff653d67..c922cf5504 100644
--- a/jre_emul/android/platform/libcore/harmony-tests/src/test/java/org/apache/harmony/tests/java/lang/ByteTest.java
+++ b/jre_emul/android/platform/libcore/harmony-tests/src/test/java/org/apache/harmony/tests/java/lang/ByteTest.java
@@ -40,10 +40,10 @@ public void test_valueOfB() {
      * java.lang.Byte#hashCode()
      */
     public void test_hashCode() {
-        assertEquals(1, new Byte((byte) 1).hashCode());
-        assertEquals(2, new Byte((byte) 2).hashCode());
+        assertEquals(-1640531535, new Byte((byte) 1).hashCode());
+        assertEquals(1013904226, new Byte((byte) 2).hashCode());
         assertEquals(0, new Byte((byte) 0).hashCode());
-        assertEquals(-1, new Byte((byte) -1).hashCode());
+        assertEquals(-1640531535, new Byte((byte) -1).hashCode());
     }
 
     /**
@@ -510,8 +510,8 @@ public void test_floatValue2() {
      * java.lang.Byte#hashCode()
      */
     public void test_hashCode2() {
-        // Test for method int java.lang.Byte.hashCode()
-        assertEquals("Incorrect hash returned", 127, new Byte((byte) 127).hashCode());
+    // Test for method int java.lang.Byte.hashCode()
+    assertEquals("Incorrect hash returned", 2105892559, new Byte((byte) 127).hashCode());
     }
 
     /**
diff --git a/jre_emul/android/platform/libcore/harmony-tests/src/test/java/org/apache/harmony/tests/java/lang/FloatTest.java b/jre_emul/android/platform/libcore/harmony-tests/src/test/java/org/apache/harmony/tests/java/lang/FloatTest.java
index 0353068d09..28bcf1c944 100644
--- a/jre_emul/android/platform/libcore/harmony-tests/src/test/java/org/apache/harmony/tests/java/lang/FloatTest.java
+++ b/jre_emul/android/platform/libcore/harmony-tests/src/test/java/org/apache/harmony/tests/java/lang/FloatTest.java
@@ -207,16 +207,13 @@ public void test_floatValue() {
     public void test_hashCode() {
         // Test for method int java.lang.Float.hashCode()
         Float f = new Float(1908.8786f);
-        assertTrue("Returned invalid hash code for 1908.8786f", f.hashCode() == Float
-                .floatToIntBits(1908.8786f));
+        assertEquals("Returned invalid hash code for 1908.8786f", -743541531, f.hashCode());
 
         f = new Float(-1.112f);
-        assertTrue("Returned invalid hash code for -1.112", f.hashCode() == Float
-                .floatToIntBits(-1.112f));
+        assertEquals("Returned invalid hash code for -1.112", -1640531535, f.hashCode());
 
         f = new Float(0f);
-        assertTrue("Returned invalid hash code for 0", f.hashCode() == Float.floatToIntBits(0f));
-
+        assertEquals("Returned invalid hash code for 0", 0, f.hashCode());
     }
 
     /**
diff --git a/jre_emul/android/platform/libcore/harmony-tests/src/test/java/org/apache/harmony/tests/java/lang/IntegerTest.java b/jre_emul/android/platform/libcore/harmony-tests/src/test/java/org/apache/harmony/tests/java/lang/IntegerTest.java
index 3c7faa304e..4a552da257 100644
--- a/jre_emul/android/platform/libcore/harmony-tests/src/test/java/org/apache/harmony/tests/java/lang/IntegerTest.java
+++ b/jre_emul/android/platform/libcore/harmony-tests/src/test/java/org/apache/harmony/tests/java/lang/IntegerTest.java
@@ -283,8 +283,8 @@ public void test_hashCode2() {
 
         Integer i1 = new Integer(1000);
         Integer i2 = new Integer(-1000);
-        assertTrue("Returned incorrect hashcode", i1.hashCode() == 1000
-                && (i2.hashCode() == -1000));
+        assertTrue("Returned incorrect hashcode", i1.hashCode() == 145972072
+                && (i2.hashCode() == 145972072));
     }
 
     /**
@@ -688,10 +688,10 @@ public void test_valueOfI() {
      * java.lang.Integer#hashCode()
      */
     public void test_hashCode() {
-        assertEquals(1, new Integer(1).hashCode());
-        assertEquals(2, new Integer(2).hashCode());
+        assertEquals(-1640531535, new Integer(1).hashCode());
+        assertEquals(1013904226, new Integer(2).hashCode());
         assertEquals(0, new Integer(0).hashCode());
-        assertEquals(-1, new Integer(-1).hashCode());
+        assertEquals(-1640531535, new Integer(-1).hashCode());
     }
 
     /**
diff --git a/jre_emul/android/platform/libcore/harmony-tests/src/test/java/org/apache/harmony/tests/java/lang/LongTest.java b/jre_emul/android/platform/libcore/harmony-tests/src/test/java/org/apache/harmony/tests/java/lang/LongTest.java
index 9da75cfc42..330e1cc723 100644
--- a/jre_emul/android/platform/libcore/harmony-tests/src/test/java/org/apache/harmony/tests/java/lang/LongTest.java
+++ b/jre_emul/android/platform/libcore/harmony-tests/src/test/java/org/apache/harmony/tests/java/lang/LongTest.java
@@ -526,10 +526,10 @@ public void test_valueOfJ() {
      * java.lang.Long#hashCode()
      */
     public void test_hashCode() {
-        assertEquals((int) (1L ^ (1L >>> 32)), new Long(1).hashCode());
-        assertEquals((int) (2L ^ (2L >>> 32)), new Long(2).hashCode());
-        assertEquals((int) (0L ^ (0L >>> 32)), new Long(0).hashCode());
-        assertEquals((int) (-1L ^ (-1L >>> 32)), new Long(-1).hashCode());
+        assertEquals(-1640531535, new Long(1).hashCode());
+        assertEquals(1013904226, new Long(2).hashCode());
+        assertEquals(0, new Long(0).hashCode());
+        assertEquals(-1640531535, new Long(-1).hashCode());
     }
 
     /**
diff --git a/jre_emul/android/platform/libcore/harmony-tests/src/test/java/org/apache/harmony/tests/java/lang/ShortTest.java b/jre_emul/android/platform/libcore/harmony-tests/src/test/java/org/apache/harmony/tests/java/lang/ShortTest.java
index bf747e7005..03a767fabe 100644
--- a/jre_emul/android/platform/libcore/harmony-tests/src/test/java/org/apache/harmony/tests/java/lang/ShortTest.java
+++ b/jre_emul/android/platform/libcore/harmony-tests/src/test/java/org/apache/harmony/tests/java/lang/ShortTest.java
@@ -361,10 +361,10 @@ public void test_valueOfS() {
      * java.lang.Short#hashCode()
      */
     public void test_hashCode() {
-        assertEquals(1, new Short((short) 1).hashCode());
-        assertEquals(2, new Short((short) 2).hashCode());
+        assertEquals(-1640531535, new Short((short) 1).hashCode());
+        assertEquals(1013904226, new Short((short) 2).hashCode());
         assertEquals(0, new Short((short) 0).hashCode());
-        assertEquals(-1, new Short((short) -1).hashCode());
+        assertEquals(-1640531535, new Short((short) -1).hashCode());
     }
 
     /**
diff --git a/jre_emul/android/platform/libcore/harmony-tests/src/test/java/org/apache/harmony/tests/java/util/FormatterTest.java b/jre_emul/android/platform/libcore/harmony-tests/src/test/java/org/apache/harmony/tests/java/util/FormatterTest.java
index b3f9452f55..028daac630 100644
--- a/jre_emul/android/platform/libcore/harmony-tests/src/test/java/org/apache/harmony/tests/java/util/FormatterTest.java
+++ b/jre_emul/android/platform/libcore/harmony-tests/src/test/java/org/apache/harmony/tests/java/util/FormatterTest.java
@@ -773,7 +773,7 @@ public void test_ioException() throws IOException {
 
         formatter = new Formatter(Locale.FRANCE);
         formatter.format(
-                "xx%1$s22%2$s%s%<s%5$s%<s&%7$h%2$s%8$s%<s%s%s%<ssuffix", "1",
+                "xx%1$s22%2$s%s%<s%5$s%<s&%7$s%2$s%8$s%<s%s%s%<ssuffix", "1",
                 "2", "3", "4", "5", "6", 7, "8", "9", "10", "11");
         assertEquals("xx12221155&7288233suffix", formatter.toString());
 
diff --git a/jre_emul/android/platform/libcore/ojluni/src/main/java/java/lang/Byte.java b/jre_emul/android/platform/libcore/ojluni/src/main/java/java/lang/Byte.java
index be1fa4e22f..4d7820487f 100644
--- a/jre_emul/android/platform/libcore/ojluni/src/main/java/java/lang/Byte.java
+++ b/jre_emul/android/platform/libcore/ojluni/src/main/java/java/lang/Byte.java
@@ -25,6 +25,8 @@
 
 package java.lang;
 
+import com.google.j2objc.util.ReflectionUtil;
+
 /* J2ObjC removed
 import jdk.internal.vm.annotation.IntrinsicCandidate;
 import libcore.util.HexEncoding;
@@ -475,17 +477,16 @@ public int hashCode() {
         return Byte.hashCode(value);
     }
 
-    /**
-     * Returns a hash code for a {@code byte} value; compatible with
-     * {@code Byte.hashCode()}.
-     *
-     * @param value the value to hash
-     * @return a hash code value for a {@code byte} value.
-     * @since 1.8
-     */
-    public static int hashCode(byte value) {
-        return (int)value;
-    }
+  /**
+   * Returns a hash code for a {@code byte} value; compatible with {@code Byte.hashCode()}.
+   *
+   * @param value the value to hash
+   * @return a hash code value for a {@code byte} value.
+   * @since 1.8
+   */
+  public static native int hashCode(byte value) /*-[
+        return (jint)[@(value) hash];
+    ]-*/;
 
     /**
      * Compares this object to the specified object.  The result is
@@ -498,8 +499,8 @@ public static int hashCode(byte value) {
      *                  {@code false} otherwise.
      */
     public boolean equals(Object obj) {
-        if (obj instanceof Byte) {
-            return value == ((Byte)obj).byteValue();
+    if (obj instanceof Byte || ReflectionUtil.isObjCNumber(obj)) {
+      return value == ((Number) obj).byteValue();
         }
         return false;
     }
diff --git a/jre_emul/android/platform/libcore/ojluni/src/main/java/java/lang/Double.java b/jre_emul/android/platform/libcore/ojluni/src/main/java/java/lang/Double.java
index da23f9951f..854b5aafc2 100644
--- a/jre_emul/android/platform/libcore/ojluni/src/main/java/java/lang/Double.java
+++ b/jre_emul/android/platform/libcore/ojluni/src/main/java/java/lang/Double.java
@@ -31,6 +31,7 @@
 import jdk.internal.vm.annotation.IntrinsicCandidate;
 */
 
+import com.google.j2objc.util.ReflectionUtil;
 import sun.misc.FloatingDecimal;
 import sun.misc.DoubleConsts;
 
@@ -897,10 +898,9 @@ public int hashCode() {
      * @return a hash code value for a {@code double} value.
      * @since 1.8
      */
-    public static int hashCode(double value) {
-        long bits = doubleToLongBits(value);
-        return (int)(bits ^ (bits >>> 32));
-    }
+    public static native int hashCode(double value) /*-[
+        return (jint)[@(value) hash];
+    ]-*/;
 
     /**
      * Compares this object against the specified object.  The result
@@ -927,8 +927,8 @@ public static int hashCode(double value) {
      * @jls 15.21.1 Numerical Equality Operators == and !=
      */
     public boolean equals(Object obj) {
-        return (obj instanceof Double)
-               && (doubleToLongBits(((Double)obj).value) ==
+        return (obj instanceof Double || ReflectionUtil.isObjCNumber(obj))
+               && (doubleToLongBits(((Number) obj).doubleValue()) ==
                       doubleToLongBits(value));
     }
 
diff --git a/jre_emul/android/platform/libcore/ojluni/src/main/java/java/lang/Float.java b/jre_emul/android/platform/libcore/ojluni/src/main/java/java/lang/Float.java
index 65a828c791..59c9ff5279 100644
--- a/jre_emul/android/platform/libcore/ojluni/src/main/java/java/lang/Float.java
+++ b/jre_emul/android/platform/libcore/ojluni/src/main/java/java/lang/Float.java
@@ -34,6 +34,7 @@
 */
 // END Android-removed: dynamic constants not supported on Android.
 
+import com.google.j2objc.util.ReflectionUtil;
 import sun.misc.FloatingDecimal;
 
 /**
@@ -720,9 +721,9 @@ public int hashCode() {
      * @return a hash code value for a {@code float} value.
      * @since 1.8
      */
-    public static int hashCode(float value) {
-        return floatToIntBits(value);
-    }
+    public static native int hashCode(float value) /*-[
+        return (jint)[@(value) hash];
+    ]-*/;
 
     /**
      * Compares this object against the specified object.  The result
@@ -752,8 +753,8 @@ public static int hashCode(float value) {
      * @jls 15.21.1 Numerical Equality Operators == and !=
      */
     public boolean equals(Object obj) {
-        return (obj instanceof Float)
-               && (floatToIntBits(((Float)obj).value) == floatToIntBits(value));
+        return (obj instanceof Float || ReflectionUtil.isObjCNumber(obj))
+               && (floatToIntBits(((Number) obj).floatValue()) == floatToIntBits(value));
     }
 
     /**
diff --git a/jre_emul/android/platform/libcore/ojluni/src/main/java/java/lang/Integer.java b/jre_emul/android/platform/libcore/ojluni/src/main/java/java/lang/Integer.java
index c80daca4e7..6ca133ba0f 100644
--- a/jre_emul/android/platform/libcore/ojluni/src/main/java/java/lang/Integer.java
+++ b/jre_emul/android/platform/libcore/ojluni/src/main/java/java/lang/Integer.java
@@ -25,6 +25,8 @@
 
 package java.lang;
 
+import com.google.j2objc.util.ReflectionUtil;
+
 /* J2ObjC removed
 import jdk.internal.vm.annotation.IntrinsicCandidate;
 */
@@ -1039,9 +1041,9 @@ public int hashCode() {
      *
      * @return a hash code value for an {@code int} value.
      */
-    public static int hashCode(int value) {
-        return value;
-    }
+    public static native int hashCode(int value) /*-[
+        return (jint)[@(value) hash];
+    ]-*/;
 
     /**
      * Compares this object to the specified object.  The result is
@@ -1054,8 +1056,8 @@ public static int hashCode(int value) {
      *          {@code false} otherwise.
      */
     public boolean equals(Object obj) {
-        if (obj instanceof Integer) {
-            return value == ((Integer)obj).intValue();
+        if (obj instanceof Integer || ReflectionUtil.isObjCNumber(obj)) {
+            return value == ((Number) obj).intValue();
         }
         return false;
     }
diff --git a/jre_emul/android/platform/libcore/ojluni/src/main/java/java/lang/Long.java b/jre_emul/android/platform/libcore/ojluni/src/main/java/java/lang/Long.java
index ea619a5576..20bce5b722 100644
--- a/jre_emul/android/platform/libcore/ojluni/src/main/java/java/lang/Long.java
+++ b/jre_emul/android/platform/libcore/ojluni/src/main/java/java/lang/Long.java
@@ -25,6 +25,8 @@
 
 package java.lang;
 
+import com.google.j2objc.util.ReflectionUtil;
+
 /* J2ObjC removed
 import jdk.internal.vm.annotation.IntrinsicCandidate;
 */
@@ -1265,9 +1267,9 @@ public int hashCode() {
      * @return a hash code value for a {@code long} value.
      * @since 1.8
      */
-    public static int hashCode(long value) {
-        return (int)(value ^ (value >>> 32));
-    }
+    public static native int hashCode(long value) /*-[
+        return (jint)[@(value) hash];
+    ]-*/;
 
     /**
      * Compares this object to the specified object.  The result is
@@ -1280,8 +1282,8 @@ public static int hashCode(long value) {
      *          {@code false} otherwise.
      */
     public boolean equals(Object obj) {
-        if (obj instanceof Long) {
-            return value == ((Long)obj).longValue();
+        if (obj instanceof Long || ReflectionUtil.isObjCNumber(obj)) {
+            return value == ((Number) obj).longValue();
         }
         return false;
     }
diff --git a/jre_emul/android/platform/libcore/ojluni/src/main/java/java/lang/Short.java b/jre_emul/android/platform/libcore/ojluni/src/main/java/java/lang/Short.java
index 4be3273042..cf9be3751e 100644
--- a/jre_emul/android/platform/libcore/ojluni/src/main/java/java/lang/Short.java
+++ b/jre_emul/android/platform/libcore/ojluni/src/main/java/java/lang/Short.java
@@ -25,6 +25,8 @@
 
 package java.lang;
 
+import com.google.j2objc.util.ReflectionUtil;
+
 /* J2ObjC removed
 import jdk.internal.vm.annotation.IntrinsicCandidate;
 */
@@ -479,17 +481,16 @@ public int hashCode() {
         return Short.hashCode(value);
     }
 
-    /**
-     * Returns a hash code for a {@code short} value; compatible with
-     * {@code Short.hashCode()}.
-     *
-     * @param value the value to hash
-     * @return a hash code value for a {@code short} value.
-     * @since 1.8
-     */
-    public static int hashCode(short value) {
-        return (int)value;
-    }
+  /**
+   * Returns a hash code for a {@code short} value; compatible with {@code Short.hashCode()}.
+   *
+   * @param value the value to hash
+   * @return a hash code value for a {@code short} value.
+   * @since 1.8
+   */
+  public static native int hashCode(short value) /*-[
+        return (jint)[@(value) hash];
+    ]-*/;
 
     /**
      * Compares this object to the specified object.  The result is
@@ -502,8 +503,8 @@ public static int hashCode(short value) {
      *                  {@code false} otherwise.
      */
     public boolean equals(Object obj) {
-        if (obj instanceof Short) {
-            return value == ((Short)obj).shortValue();
+    if (obj instanceof Short || ReflectionUtil.isObjCNumber(obj)) {
+      return value == ((Number) obj).shortValue();
         }
         return false;
     }
diff --git a/jre_emul/android/platform/libcore/ojluni/src/main/java/java/util/Arrays.java b/jre_emul/android/platform/libcore/ojluni/src/main/java/java/util/Arrays.java
index 19770da14b..9a6669f859 100644
--- a/jre_emul/android/platform/libcore/ojluni/src/main/java/java/util/Arrays.java
+++ b/jre_emul/android/platform/libcore/ojluni/src/main/java/java/util/Arrays.java
@@ -4084,8 +4084,7 @@ public static int hashCode(long a[]) {
 
         int result = 1;
         for (long element : a) {
-            int elementHash = (int)(element ^ (element >>> 32));
-            result = 31 * result + elementHash;
+            result = 31 * result + Long.hashCode(element);
         }
 
         return result;
@@ -4113,7 +4112,7 @@ public static int hashCode(int a[]) {
 
         int result = 1;
         for (int element : a)
-            result = 31 * result + element;
+            result = 31 * result + Integer.hashCode(element);
 
         return result;
     }
@@ -4140,7 +4139,7 @@ public static int hashCode(short a[]) {
 
         int result = 1;
         for (short element : a)
-            result = 31 * result + element;
+            result = 31 * result + Short.hashCode(element);
 
         return result;
     }
@@ -4194,7 +4193,7 @@ public static int hashCode(byte a[]) {
 
         int result = 1;
         for (byte element : a)
-            result = 31 * result + element;
+            result = 31 * result + Byte.hashCode(element);
 
         return result;
     }
@@ -4248,7 +4247,7 @@ public static int hashCode(float a[]) {
 
         int result = 1;
         for (float element : a)
-            result = 31 * result + Float.floatToIntBits(element);
+            result = 31 * result + Float.hashCode(element);
 
         return result;
     }
@@ -4275,8 +4274,7 @@ public static int hashCode(double a[]) {
 
         int result = 1;
         for (double element : a) {
-            long bits = Double.doubleToLongBits(element);
-            result = 31 * result + (int)(bits ^ (bits >>> 32));
+            result = 31 * result + Double.hashCode(element);
         }
         return result;
     }
diff --git a/jre_emul/misc_tests/com/google/j2objc/ReflectionTest.java b/jre_emul/misc_tests/com/google/j2objc/ReflectionTest.java
index cd9fb13eb5..041d131c14 100644
--- a/jre_emul/misc_tests/com/google/j2objc/ReflectionTest.java
+++ b/jre_emul/misc_tests/com/google/j2objc/ReflectionTest.java
@@ -201,4 +201,51 @@ public void testAnnotationInitializedWithDefaults() {
     assertEquals("hello", a.annotationValue().value());
     assertEquals(Iterable.class, a.classValue());
   }
+
+  private static native Object getNativeNumber(long val) /*-[
+    return [NSNumber numberWithLongLong:(long long)val];
+  ]-*/;
+
+  public void testIsObjCNumber() {
+    Object nativeNum = getNativeNumber(42);
+    Object javaNum = Integer.valueOf(42);
+    Object decimalNum = new java.math.BigDecimal("1.23");
+
+    assertTrue(com.google.j2objc.util.ReflectionUtil.isObjCNumber(nativeNum));
+    assertFalse(com.google.j2objc.util.ReflectionUtil.isObjCNumber(javaNum));
+    assertFalse(com.google.j2objc.util.ReflectionUtil.isObjCNumber(decimalNum));
+    assertFalse(com.google.j2objc.util.ReflectionUtil.isObjCNumber("not a number"));
+    assertFalse(com.google.j2objc.util.ReflectionUtil.isObjCNumber(null));
+  }
+
+  public void testNumberHashMapCompatibility() {
+    java.util.HashMap<Number, String> map = new java.util.HashMap<>();
+
+    // Test with positive number (sign bit not set)
+    Object javaInt = Integer.valueOf(42);
+    Object objcInt = getNativeNumber(42);
+
+    map.put((Number) javaInt, "success");
+    assertEquals(1, map.size());
+    assertEquals("success", map.get(objcInt));
+
+    // Overwrite existing key (proves equals() and hashCode() consistency in map bucket resolution)
+    map.put((Number) objcInt, "success_reverse");
+    assertEquals(1, map.size());
+    assertEquals("success_reverse", map.get(javaInt));
+
+    // Test with negative number (sign bit set in the hash code)
+    map.clear();
+    Object javaIntMinus1 = Integer.valueOf(-1);
+    Object objcIntMinus1 = getNativeNumber(-1);
+
+    map.put((Number) javaIntMinus1, "success_minus1");
+    assertEquals(1, map.size());
+    assertEquals("success_minus1", map.get(objcIntMinus1));
+
+    // Overwrite existing key
+    map.put((Number) objcIntMinus1, "success_minus1_reverse");
+    assertEquals(1, map.size());
+    assertEquals("success_minus1_reverse", map.get(javaIntMinus1));
+  }
 }