diff --git a/core/java/android/net/Uri.java b/core/java/android/net/Uri.java
index e1556b4..c0b0cee 100644
--- a/core/java/android/net/Uri.java
+++ b/core/java/android/net/Uri.java
@@ -24,8 +24,6 @@
 import android.os.StrictMode;
 import android.util.Log;
 
-import libcore.net.UriCodec;
-
 import java.io.File;
 import java.io.IOException;
 import java.io.UnsupportedEncodingException;
@@ -1951,7 +1949,8 @@
         if (s == null) {
             return null;
         }
-        return UriCodec.decode(s, false, StandardCharsets.UTF_8, false);
+        return UriCodec.decode(
+                s, false /* convertPlus */, StandardCharsets.UTF_8, false /* throwOnFailure */);
     }
 
     /**
diff --git a/core/java/android/net/UriCodec.java b/core/java/android/net/UriCodec.java
new file mode 100644
index 0000000..e1470e0
--- /dev/null
+++ b/core/java/android/net/UriCodec.java
@@ -0,0 +1,176 @@
+/*
+ * Copyright (C) 2015 The Android Open Source Project
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *      http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+package android.net;
+
+import java.net.URISyntaxException;
+import java.nio.ByteBuffer;
+import java.nio.charset.CharacterCodingException;
+import java.nio.charset.Charset;
+import java.nio.charset.CharsetDecoder;
+import java.nio.charset.CodingErrorAction;
+
+/**
+ * Decodes “application/x-www-form-urlencoded” content.
+ *
+ * @hide
+ */
+public final class UriCodec {
+
+    private UriCodec() {}
+
+    /**
+     * Interprets a char as hex digits, returning a number from -1 (invalid char) to 15 ('f').
+     */
+    private static int hexCharToValue(char c) {
+        if ('0' <= c && c <= '9') {
+            return c - '0';
+        }
+        if ('a' <= c && c <= 'f') {
+            return 10 + c - 'a';
+        }
+        if ('A' <= c && c <= 'F') {
+            return 10 + c - 'A';
+        }
+        return -1;
+    }
+
+    private static URISyntaxException unexpectedCharacterException(
+            String uri, String name, char unexpected, int index) {
+        String nameString = (name == null) ? "" :  " in [" + name + "]";
+        return new URISyntaxException(
+                uri, "Unexpected character" + nameString + ": " + unexpected, index);
+    }
+
+    private static char getNextCharacter(String uri, int index, int end, String name)
+             throws URISyntaxException {
+        if (index >= end) {
+            String nameString = (name == null) ? "" :  " in [" + name + "]";
+            throw new URISyntaxException(
+                    uri, "Unexpected end of string" + nameString, index);
+        }
+        return uri.charAt(index);
+    }
+
+    /**
+     * Decode a string according to the rules of this decoder.
+     *
+     * - if {@code convertPlus == true} all ‘+’ chars in the decoded output are converted to ‘ ‘
+     *   (white space)
+     * - if {@code throwOnFailure == true}, an {@link IllegalArgumentException} is thrown for
+     *   invalid inputs. Else, U+FFFd is emitted to the output in place of invalid input octets.
+     */
+    public static String decode(
+            String s, boolean convertPlus, Charset charset, boolean throwOnFailure) {
+        StringBuilder builder = new StringBuilder(s.length());
+        appendDecoded(builder, s, convertPlus, charset, throwOnFailure);
+        return builder.toString();
+    }
+
+    /**
+     * Character to be output when there's an error decoding an input.
+     */
+    private static final char INVALID_INPUT_CHARACTER = '\ufffd';
+
+    private static void appendDecoded(
+            StringBuilder builder,
+            String s,
+            boolean convertPlus,
+            Charset charset,
+            boolean throwOnFailure) {
+        CharsetDecoder decoder = charset.newDecoder()
+                .onMalformedInput(CodingErrorAction.REPLACE)
+                .replaceWith("\ufffd")
+                .onUnmappableCharacter(CodingErrorAction.REPORT);
+        // Holds the bytes corresponding to the escaped chars being read (empty if the last char
+        // wasn't a escaped char).
+        ByteBuffer byteBuffer = ByteBuffer.allocate(s.length());
+        int i = 0;
+        while (i < s.length()) {
+            char c = s.charAt(i);
+            i++;
+            switch (c) {
+                case '+':
+                    flushDecodingByteAccumulator(
+                            builder, decoder, byteBuffer, throwOnFailure);
+                    builder.append(convertPlus ? ' ' : '+');
+                    break;
+                case '%':
+                    // Expect two characters representing a number in hex.
+                    byte hexValue = 0;
+                    for (int j = 0; j < 2; j++) {
+                        try {
+                            c = getNextCharacter(s, i, s.length(), null /* name */);
+                        } catch (URISyntaxException e) {
+                            // Unexpected end of input.
+                            if (throwOnFailure) {
+                                throw new IllegalArgumentException(e);
+                            } else {
+                                flushDecodingByteAccumulator(
+                                        builder, decoder, byteBuffer, throwOnFailure);
+                                builder.append(INVALID_INPUT_CHARACTER);
+                                return;
+                            }
+                        }
+                        i++;
+                        int newDigit = hexCharToValue(c);
+                        if (newDigit < 0) {
+                            if (throwOnFailure) {
+                                throw new IllegalArgumentException(
+                                        unexpectedCharacterException(s, null /* name */, c, i - 1));
+                            } else {
+                                flushDecodingByteAccumulator(
+                                        builder, decoder, byteBuffer, throwOnFailure);
+                                builder.append(INVALID_INPUT_CHARACTER);
+                                break;
+                            }
+                        }
+                        hexValue = (byte) (hexValue * 0x10 + newDigit);
+                    }
+                    byteBuffer.put(hexValue);
+                    break;
+                default:
+                    flushDecodingByteAccumulator(builder, decoder, byteBuffer, throwOnFailure);
+                    builder.append(c);
+            }
+        }
+        flushDecodingByteAccumulator(builder, decoder, byteBuffer, throwOnFailure);
+    }
+
+    private static void flushDecodingByteAccumulator(
+            StringBuilder builder,
+            CharsetDecoder decoder,
+            ByteBuffer byteBuffer,
+            boolean throwOnFailure) {
+        if (byteBuffer.position() == 0) {
+            return;
+        }
+        byteBuffer.flip();
+        try {
+            builder.append(decoder.decode(byteBuffer));
+        } catch (CharacterCodingException e) {
+            if (throwOnFailure) {
+                throw new IllegalArgumentException(e);
+            } else {
+                builder.append(INVALID_INPUT_CHARACTER);
+            }
+        } finally {
+            // Use the byte buffer to write again.
+            byteBuffer.flip();
+            byteBuffer.limit(byteBuffer.capacity());
+        }
+    }
+}
diff --git a/core/tests/coretests/src/android/net/UriCodecTest.java b/core/tests/coretests/src/android/net/UriCodecTest.java
new file mode 100644
index 0000000..7fe9402
--- /dev/null
+++ b/core/tests/coretests/src/android/net/UriCodecTest.java
@@ -0,0 +1,108 @@
+/*
+ * Copyright (C) 2015 The Android Open Source Project
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *      http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+package android.net;
+
+import junit.framework.TestCase;
+
+import java.nio.charset.StandardCharsets;
+
+/**
+ * Tests for {@link UriCodec}
+ */
+public class UriCodecTest extends TestCase {
+
+    public void testDecode_emptyString_returnsEmptyString() {
+        assertEquals("", UriCodec.decode("",
+                false /* convertPlus */,
+                StandardCharsets.UTF_8,
+                true /* throwOnFailure */));
+    }
+
+    public void testDecode_wrongHexDigit_fails() {
+        try {
+            // %p in the end.
+            UriCodec.decode("ab%2f$%C4%82%25%e0%a1%80%p",
+                    false /* convertPlus */,
+                    StandardCharsets.UTF_8,
+                    true /* throwOnFailure */);
+            fail("Expected URISyntaxException");
+        } catch (IllegalArgumentException expected) {
+            // Expected.
+        }
+    }
+
+    public void testDecode_secondHexDigitWrong_fails() {
+        try {
+            // %1p in the end.
+            UriCodec.decode("ab%2f$%c4%82%25%e0%a1%80%1p",
+                    false /* convertPlus */,
+                    StandardCharsets.UTF_8,
+                    true /* throwOnFailure */);
+            fail("Expected URISyntaxException");
+        } catch (IllegalArgumentException expected) {
+            // Expected.
+        }
+    }
+
+    public void testDecode_endsWithPercent_fails() {
+        try {
+            // % in the end.
+            UriCodec.decode("ab%2f$%c4%82%25%e0%a1%80%",
+                    false /* convertPlus */,
+                    StandardCharsets.UTF_8,
+                    true /* throwOnFailure */);
+            fail("Expected URISyntaxException");
+        } catch (IllegalArgumentException expected) {
+            // Expected.
+        }
+    }
+
+    public void testDecode_dontThrowException_appendsUnknownCharacter() {
+        assertEquals("ab/$\u0102%\u0840\ufffd",
+                UriCodec.decode("ab%2f$%c4%82%25%e0%a1%80%",
+                        false /* convertPlus */,
+                        StandardCharsets.UTF_8,
+                        false /* throwOnFailure */));
+    }
+
+    public void testDecode_convertPlus() {
+        assertEquals("ab/$\u0102% \u0840",
+                UriCodec.decode("ab%2f$%c4%82%25+%e0%a1%80",
+                        true /* convertPlus */,
+                        StandardCharsets.UTF_8,
+                        false /* throwOnFailure */));
+    }
+
+    // Last character needs decoding (make sure we are flushing the buffer with chars to decode).
+    public void testDecode_lastCharacter() {
+        assertEquals("ab/$\u0102%\u0840",
+                UriCodec.decode("ab%2f$%c4%82%25%e0%a1%80",
+                        false /* convertPlus */,
+                        StandardCharsets.UTF_8,
+                        true /* throwOnFailure */));
+    }
+
+    // Check that a second row of encoded characters is decoded properly (internal buffers are
+    // reset properly).
+    public void testDecode_secondRowOfEncoded() {
+        assertEquals("ab/$\u0102%\u0840aa\u0840",
+                UriCodec.decode("ab%2f$%c4%82%25%e0%a1%80aa%e0%a1%80",
+                        false /* convertPlus */,
+                        StandardCharsets.UTF_8,
+                        true /* throwOnFailure */));
+    }
+}