Add jep511 module: module import declarations on JDK 25 and 27

Runnable sources, deliberate compile failures, three small modules and nine captured transcripts for import module (JEP 511).

Co-Authored-By: Claude Sonnet 5 <[email protected]>
Claude-Session: https://claude.ai/code/session_01TF9JWFvJSNm6HVzswzZU5a

jep511/src/CompactAmbiguous.java

@@ -0,0 +1,6 @@
+import module java.sql;
+
+void main() {
+    Date d = new Date(0L);      // implicit java.base (java.util.Date) vs explicit java.sql (java.sql.Date)
+    IO.println(d.getClass().getName());
+}

jep511/src/CompactNoImport.java

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+void main() {
+    IO.println(List.of("no imports at all"));
+}

jep511/src/CompactPlusImport.java

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+import module java.sql;
+
+void main() {
+    var l = List.of("java.base came implicitly");      // no import module java.base written
+    IO.println(l + " " + Connection.TRANSACTION_NONE);  // java.sql from the explicit import
+}

jep511/src/DuplicateImports.java

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+import module java.base;
+import module java.base;
+import java.util.List;
+import java.util.List;
+
+public class DuplicateImports {
+    public static void main(String[] args) {
+        System.out.println(List.of("dups are fine"));
+    }
+}

jep511/src/FixedDate.java

@@ -0,0 +1,12 @@
+import module java.base;
+import module java.sql;
+import java.util.Date;          // a single-type import wins over both module imports
+
+public class FixedDate {
+    public static void main(String[] args) {
+        Date d = new Date(0L);
+        System.out.println(d.getClass().getName());
+        java.sql.Date s = new java.sql.Date(0L);   // the other one is still reachable by its full name
+        System.out.println(s.getClass().getName());
+    }
+}

jep511/src/InPackage.java

@@ -0,0 +1,9 @@
+package demo.mod;
+
+import module java.base;
+
+public class InPackage {
+    public static void main(String[] args) {
+        System.out.println(List.of(1, 2, 3) + " from package " + InPackage.class.getPackageName());
+    }
+}

jep511/src/JavaSe.java

@@ -0,0 +1,10 @@
+import module java.se;
+import java.util.List;                  // java.se brings in java.desktop, whose java.awt.List clashes with java.util.List
+
+public class JavaSe {
+    public static void main(String[] args) {
+        List<String> l = List.of("a");                    // java.base
+        Logger lg = Logger.getLogger("x");                // java.logging
+        System.out.println(l + " " + lg.getName() + " " + Connection.TRANSACTION_NONE);  // java.sql
+    }
+}

jep511/src/NewWay.java

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+import module java.base;
+
+public class NewWay {
+    public static void main(String[] args) {
+        List<String> words = List.of("apple", "avocado", "banana", "blueberry", "cherry");
+        Map<Character, List<String>> byInitial = words.stream()
+                .collect(Collectors.groupingBy(w -> w.charAt(0)));
+        System.out.println(byInitial);
+        System.out.println(Path.of("a", "b", "c.txt") + " on " + LocalDate.of(2026, 9, 15));
+    }
+}

jep511/src/OldWay.java

@@ -0,0 +1,17 @@
+import java.nio.file.Path;
+import java.time.LocalDate;
+import java.util.List;
+import java.util.Map;
+import java.util.function.Function;
+import java.util.stream.Collectors;
+import java.util.stream.Stream;
+
+public class OldWay {
+    public static void main(String[] args) {
+        List<String> words = List.of("apple", "avocado", "banana", "blueberry", "cherry");
+        Map<Character, List<String>> byInitial = words.stream()
+                .collect(Collectors.groupingBy(w -> w.charAt(0)));
+        System.out.println(byInitial);
+        System.out.println(Path.of("a", "b", "c.txt") + " on " + LocalDate.of(2026, 9, 15));
+    }
+}

jep511/src/SamePackageWins.java

@@ -0,0 +1,12 @@
+import module java.base;
+
+class Date {                       // a class in this file's own package
+    public String toString() { return "my own Date"; }
+}
+
+public class SamePackageWins {
+    public static void main(String[] args) {
+        System.out.println(new Date());                 // which Date?
+        System.out.println(new java.util.Date(0L).getClass().getName());
+    }
+}

jep511/src/Script.java

@@ -0,0 +1,6 @@
+import module java.base;
+
+void main() {
+    var now = LocalDate.of(2026, 9, 15);
+    IO.println(Stream.of("a", "b", "c").collect(Collectors.joining("-")) + " " + now);
+}

jep511/src/StarImportWins.java

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+import java.util.*;
+import module java.sql;
+
+public class StarImportWins {
+    public static void main(String[] args) {
+        Date d = new Date(0L);
+        System.out.println(d.getClass().getName());
+    }
+}

jep511/src/StarImportWinsSql.java

@@ -0,0 +1,9 @@
+import java.sql.*;
+import module java.base;
+
+public class StarImportWinsSql {
+    public static void main(String[] args) {
+        Date d = new Date(0L);
+        System.out.println(d.getClass().getName());
+    }
+}

jep511/src/ThirdParty.java

@@ -0,0 +1,5 @@
+import module acme.text;
+
+void main() {
+    IO.println(Slug.of("A script using a library module"));
+}

jep511/src/Transitive.java

@@ -0,0 +1,15 @@
+import module java.base;
+import module java.sql;
+
+public class Transitive {
+    public static void main(String[] args) {
+        // java.sql declares "requires transitive" java.logging, java.xml and java.transaction.xa,
+        // so importing java.sql also imports their exported packages.
+        Logger log = Logger.getLogger("demo");                     // java.util.logging   (java.logging)
+        System.out.println(log.getName());
+        System.out.println(XAResource.TMNOFLAGS);                  // javax.transaction.xa (java.transaction.xa)
+        System.out.println(DocumentBuilderFactory.class.getModule().getName());  // javax.xml.parsers (java.xml)
+        List<String> l = List.of("java.base needed its own import");
+        System.out.println(l);
+    }
+}

jep511/src/UnusedAmbiguity.java

@@ -0,0 +1,9 @@
+import module java.base;
+import module java.sql;
+
+public class UnusedAmbiguity {
+    public static void main(String[] args) {
+        // Date is ambiguous between the two modules, but it is never used here, so this compiles.
+        System.out.println("no Date mentioned, no error");
+    }
+}

jep511/src/imports.jsh

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+/imports
+System.out.println(List.of(1, 2).stream().map(x -> x * 2).collect(Collectors.toList()))
+/exit