Merge cherrypicks of ['googleplex-android-review.googlesource.com/23914849'] into udc-release.android-vts-14.0_r1android-security-14.0.0_r8android-security-14.0.0_r7android-security-14.0.0_r6android-security-14.0.0_r5android-security-14.0.0_r4android-security-14.0.0_r3android-security-14.0.0_r2android-platform-14.0.0_r7android-platform-14.0.0_r6android-platform-14.0.0_r5android-platform-14.0.0_r4android-platform-14.0.0_r3android-platform-14.0.0_r2android-platform-14.0.0_r1android-cts-14.0_r1android-14.0.0_r28android-14.0.0_r2android-14.0.0_r15android-14.0.0_r14android-14.0.0_r13android-14.0.0_r1android14-security-releaseandroid14-s2-releaseandroid14-s1-releaseandroid14-releaseandroid14-platform-release

Change-Id: I637b7f465b04e17585518e67b72e5af64bc8d391

3 files changed, 75 insertions, 8 deletions

diff --git a/luni/src/test/java/org/apache/harmony/regex/tests/java/util/regex/PatternTest.java b/luni/src/test/java/org/apache/harmony/regex/tests/java/util/regex/PatternTest.java
index 9fc1c212920..e56dab394a0 100644
--- a/luni/src/test/java/org/apache/harmony/regex/tests/java/util/regex/PatternTest.java
+++ b/luni/src/test/java/org/apache/harmony/regex/tests/java/util/regex/PatternTest.java
@@ -33,6 +33,11 @@ import org.junit.rules.TestRule;
 
 import static java.util.Arrays.asList;
 
+import android.compat.Compatibility;
+
+import dalvik.annotation.compat.VersionCodes;
+import dalvik.system.VMRuntime;
+
 public class PatternTest extends TestCaseWithRules {
     @Rule
     public TestRule switchTargetSdkVersionRule = SwitchTargetSdkVersionRule.getInstance();
@@ -2199,16 +2204,13 @@ public class PatternTest extends TestCaseWithRules {
 
         pat = Pattern.compile("b");
         s = pat.splitAsStream("").toArray(String[]::new);
-        // The length is 1 because the javadoc says "If this pattern does not match any subsequence
-        // of the input then the resulting stream has just one element, namely the input sequence
-        // in string form.
-        assertEquals(1, s.length);
-        assertEquals(s[0], "");
+        assertEquals(getExpectedEmptyStringSplitLength(), s.length);
+        checkContainsOnlyEmptyStrings(s);
 
         pat = Pattern.compile("");
         s = pat.splitAsStream("").toArray(String[]::new);
-        assertEquals(1, s.length);
-        assertEquals(s[0], "");
+        assertEquals(getExpectedEmptyStringSplitLength(), s.length);
+        checkContainsOnlyEmptyStrings(s);
 
         pat = Pattern.compile("");
         s = pat.splitAsStream("abccbadfe").toArray(String[]::new);
@@ -2216,4 +2218,23 @@ public class PatternTest extends TestCaseWithRules {
         assertEquals(s[0], "a");
         assertEquals(s[8], "e");
     }
+
+    private int getExpectedEmptyStringSplitLength() {
+        if (VMRuntime.getSdkVersion() >= VersionCodes.UPSIDE_DOWN_CAKE
+                && Compatibility.isChangeEnabled(
+                Pattern.SPLIT_AS_STREAM_RETURNS_SINGLE_EMPTY_STRING)) {
+            // The length is 1 because the javadoc says "If this pattern does not match any
+            // subsequence of the input then the resulting stream has just one element,
+            // namely the input sequence in string form.
+            return 1;
+        } else {
+            return 0;
+        }
+    }
+
+    private void checkContainsOnlyEmptyStrings(String[] sArray) {
+        for (String s : sArray) {
+            assertEquals(s, "");
+        }
+    }
 }
diff --git a/ojluni/src/main/java/java/util/regex/Pattern.java b/ojluni/src/main/java/java/util/regex/Pattern.java
index 1caa4aeecf7..43fa23389df 100644
--- a/ojluni/src/main/java/java/util/regex/Pattern.java
+++ b/ojluni/src/main/java/java/util/regex/Pattern.java
@@ -26,7 +26,13 @@
 
 package java.util.regex;
 
+import android.compat.Compatibility;
+import android.compat.annotation.ChangeId;
+import android.compat.annotation.EnabledSince;
+
 import com.android.icu.util.regex.PatternNative;
+
+import dalvik.annotation.compat.VersionCodes;
 import dalvik.system.VMRuntime;
 import java.util.ArrayList;
 import java.util.Iterator;
@@ -5731,7 +5737,16 @@ NEXT:       while (i <= last) {
                     // If the input is an empty string then the result can only be a
                     // stream of the input.  Induce that by setting the empty
                     // element count to 1
-                    emptyElementCount = input.length() == 0 ? 1 : 0;
+                    // Android-changed: Keep old behavior on Android 13 or below. http://b/286499139
+                    // emptyElementCount = input.length() == 0 ? 1 : 0;
+                    if (input.length() == 0
+                            && VMRuntime.getSdkVersion() >= VersionCodes.UPSIDE_DOWN_CAKE
+                            && Compatibility.isChangeEnabled(
+                                    SPLIT_AS_STREAM_RETURNS_SINGLE_EMPTY_STRING)) {
+                        emptyElementCount = 1;
+                    } else {
+                        emptyElementCount = 0;
+                    }
                 }
                 if (nextElement != null || emptyElementCount > 0)
                     return true;
@@ -5768,4 +5783,19 @@ NEXT:       while (i <= last) {
         return StreamSupport.stream(Spliterators.spliteratorUnknownSize(
                 new MatcherIterator(), Spliterator.ORDERED | Spliterator.NONNULL), false);
     }
+
+    //  Android-added: Backward-compatible flag for splitAsStream() API.
+    /**
+     * Since Android 14, {@link Pattern#splitAsStream(CharSequence)} return a stream of a single
+     * empty String as described in the API documentation. Previously, given an empty string input,
+     * the method returns an empty stream.
+     *
+     * This flag is enabled for apps targeting Android 14+.
+     *
+     * @hide
+     */
+    @ChangeId
+    @EnabledSince(targetSdkVersion = VersionCodes.UPSIDE_DOWN_CAKE)
+    public static final long SPLIT_AS_STREAM_RETURNS_SINGLE_EMPTY_STRING = 288845345L;
+
 }
diff --git a/ojluni/src/test/java/util/regex/PatternStreamTest.java b/ojluni/src/test/java/util/regex/PatternStreamTest.java
index 74ff21b4316..edbd0541c98 100644
--- a/ojluni/src/test/java/util/regex/PatternStreamTest.java
+++ b/ojluni/src/test/java/util/regex/PatternStreamTest.java
@@ -37,6 +37,7 @@ import org.testng.annotations.Test;
 
 import java.util.ArrayList;
 import java.util.Arrays;
+import java.util.Collections;
 import java.util.ConcurrentModificationException;
 import java.util.List;
 import java.util.concurrent.atomic.AtomicInteger;
@@ -52,6 +53,13 @@ import org.openjdk.testlib.java.util.stream.TestData;
 
 import static org.testng.Assert.*;
 
+import static java.util.regex.Pattern.SPLIT_AS_STREAM_RETURNS_SINGLE_EMPTY_STRING;
+
+import android.compat.Compatibility;
+
+import dalvik.annotation.compat.VersionCodes;
+import dalvik.system.VMRuntime;
+
 @Test
 public class PatternStreamTest extends OpTestCase {
 
@@ -139,6 +147,14 @@ public class PatternStreamTest extends OpTestCase {
         // Derive expected result from pattern.split
         List<String> expected = Arrays.asList(pattern.split(input));
 
+        // Android-added: Keep old behavior on Android 13 or below. http://b/286499139
+        if(input.isEmpty()
+                && !(VMRuntime.getSdkVersion() >= VersionCodes.UPSIDE_DOWN_CAKE
+                && Compatibility.isChangeEnabled(
+                        Pattern.SPLIT_AS_STREAM_RETURNS_SINGLE_EMPTY_STRING))) {
+            expected = Collections.emptyList();
+        }
+
         Supplier<Stream<String>> ss =  () -> pattern.splitAsStream(input);
         withData(TestData.Factory.ofSupplier(description, ss))
                 .stream(LambdaTestHelpers.identity())