A prototype of IO not based on Console.

src/java.base/share/classes/java/lang/IO.java

@@ -0,0 +1,165 @@
+/*
+ * Copyright (c) 2024, 2025, Oracle and/or its affiliates. All rights reserved.
+ * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
+ *
+ * This code is free software; you can redistribute it and/or modify it
+ * under the terms of the GNU General Public License version 2 only, as
+ * published by the Free Software Foundation.  Oracle designates this
+ * particular file as subject to the "Classpath" exception as provided
+ * by Oracle in the LICENSE file that accompanied this code.
+ *
+ * This code is distributed in the hope that it will be useful, but WITHOUT
+ * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
+ * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License
+ * version 2 for more details (a copy is included in the LICENSE file that
+ * accompanied this code).
+ *
+ * You should have received a copy of the GNU General Public License version
+ * 2 along with this work; if not, write to the Free Software Foundation,
+ * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
+ *
+ * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
+ * or visit www.oracle.com if you need additional information or have any
+ * questions.
+ */
+
+package java.lang;
+
+import java.io.BufferedReader;
+import java.io.Console;
+import java.io.InputStreamReader;
+import java.io.IOError;
+import java.io.IOException;
+import java.nio.charset.Charset;
+import jdk.internal.javac.PreviewFeature;
+
+/**
+ * A collection of static convenience methods that provide methods for
+ * basic input/output.
+ *
+ * <p> Output from methods in this class use the conversion from
+ * characters to bytes used by {@link System#out}, i.e.
+ * {@link System##stdout.encoding stdoutencoding} by default.
+ *
+ * <p> Input from methods in this class uses the character set of
+ * the system console as specified by {@link Console#charset}, if {@code System.console()}
+ * returns a non-{@code null} value, {@code Charset.defaultCharset()} otherwise.
+ *
+ * @since 23
+ */
+@PreviewFeature(feature = PreviewFeature.Feature.IMPLICIT_CLASSES)
+public final class IO {
+
+    private static final Object readLock = new Object();
+    private static BufferedReader input;
+
+    private IO() {
+
+        throw new Error("no instances");
+    }
+
+    /**
+     * Writes a string representation of the specified object to the system
+     * output, terminates the line and then flushes that output.
+     *
+     * <p> The effect of this method is the same as for the following code:
+     * {@snippet lang="java":
+     *     System.out.println(obj);
+     *     System.out.flush();
+     * }
+     *
+     * @param obj the object to print, may be {@code null}
+     */
+    public static void println(Object obj) {
+        System.out.println(obj);
+        System.out.flush();
+    }
+
+    /**
+     * Terminates the current line on the system output and then flushes
+     * that output.
+     *
+     * <p> The effect of this method is the same as for the following code:
+     * {@snippet lang="java":
+     *     System.out.println();
+     *     System.out.flush();
+     * }
+     *
+     * @since 24
+     */
+    public static void println() {
+        println("");
+    }
+
+    /**
+     * Writes a string representation of the specified object to the system
+     * output and then flushes that output.
+     *
+     * <p> The effect of this method is the same as for the following code:
+     * {@snippet lang="java":
+     *     System.out.print(obj);
+     *     System.out.flush();
+     * }
+     *
+     *
+     * @param obj the object to print, may be {@code null}
+     */
+    public static void print(Object obj) {
+        System.out.print(obj);
+        System.out.flush();
+    }
+
+    /**
+     * Writes a prompt as if by calling {@code print}, then reads a single line
+     * of text from the system input.
+     *
+     * <p> Once this method is used, only methods in this class should be used
+     * to read from the input. Other methods (namely {@code System.in.read()} and
+     * {@code Console} give undefined results;
+     *
+     * @param prompt the prompt string, may be {@code null}
+     *
+     * @return a string containing the line read from the system console, not
+     * including any line-termination characters. Returns {@code null} if an
+     * end of stream has been reached without having read any characters.
+     *
+     * @throws IOError if an I/O error occurs
+     */
+    public static String readln(String prompt) throws IOError {
+        print(prompt);
+        synchronized (readLock) {
+            if (input == null) {
+                Console console = System.console();
+                Charset charset = console != null ? console.charset()
+                                                  : Charset.defaultCharset();
+
+                input = new BufferedReader(new InputStreamReader(System.in, charset));
+            }
+            try {
+                return input.readLine();
+            } catch (IOException ex) {
+                throw new IOError(ex);
+            }
+        }
+    }
+
+    /**
+     * Reads a single line of text from the system input.
+     *
+     * <p> Once this method is used, only methods in this class should be used
+     * to read from the input. Other methods (namely {@code System.in.read()} and
+     * {@code Console} give undefined results;
+     *
+     * @return a string containing the line read from the system console, not
+     * including any line-termination characters. Returns {@code null} if an
+     * end of stream has been reached without having read any characters.
+     *
+     * @throws IOError if an I/O error occurs
+     *
+     * @since 24
+     */
+    public static String readln() throws IOError {
+        return readln("");
+    }
+
+}

src/jdk.compiler/share/classes/com/sun/tools/javac/code/Symtab.java

@@ -230,7 +230,6 @@ public static Symtab instance(Context context) {
     public final Type valueBasedInternalType;
     public final Type classDescType;
     public final Type enumDescType;
-    public final Type ioType;
 
     // For serialization lint checking
     public final Type objectStreamFieldType;
@@ -613,7 +612,6 @@ public <R, P> R accept(ElementVisitor<R, P> v, P p) {
         valueBasedInternalType = enterSyntheticAnnotation("jdk.internal.ValueBased+Annotation");
         classDescType = enterClass("java.lang.constant.ClassDesc");
         enumDescType = enterClass("java.lang.Enum$EnumDesc");
-        ioType = enterClass("java.io.IO");
         // For serialization lint checking
         objectStreamFieldType = enterClass("java.io.ObjectStreamField");
         objectInputStreamType = enterClass("java.io.ObjectInputStream");

src/jdk.compiler/share/classes/com/sun/tools/javac/comp/TypeEnter.java

@@ -340,10 +340,6 @@ private void implicitImports(JCCompilationUnit tree, Env<AttrContext> env) {
                     (cls.mods.flags & IMPLICIT_CLASS) != 0;
             if (isImplicitClass) {
                 doModuleImport(make.ModuleImport(make.QualIdent(syms.java_base)));
-                if (peekTypeExists(syms.ioType.tsym)) {
-                    doImport(make.Import(make.Select(make.QualIdent(syms.ioType.tsym),
-                            names.asterisk), true), false);
-                }
             }
         }
 

test/jdk/java/io/IO/IO.java → test/jdk/java/lang/IO/IO.java

@@ -183,6 +183,7 @@ public void printlnNoParamsTest() throws Exception {
         var file = Path.of("PrintlnNoParams.java");
         try (Writer w = Files.newBufferedWriter(file)) {
             w.write("""
+                    import static java.lang.IO.*;
                     void main() {
                         print("1 ");
                         print("2 ");
@@ -206,20 +207,6 @@ void main() {
     }
 
 
-    @ParameterizedTest
-    @ValueSource(strings = {"println", "print", "input"})
-    public void nullConsole(String method) throws Exception {
-        var file = Path.of(System.getProperty("test.src", "."), "Methods.java")
-                .toAbsolutePath().toString();
-        var pb = ProcessTools.createTestJavaProcessBuilder("-Djdk.console=gibberish",
-                "--enable-preview", file, method);
-        OutputAnalyzer output = ProcessTools.executeProcess(pb);
-        output.reportDiagnosticSummary();
-        assertEquals(1, output.getExitValue());
-        output.shouldContain("Exception in thread \"main\" java.io.IOError");
-    }
-
-
     // adapted from https://junit.org/junit5/docs/current/user-guide/#extensions-lifecycle-callbacks-timing-extension
     // remove after CODETOOLS-7903752 propagates to jtreg that this test is routinely run by
 

test/jdk/java/io/IO/Input.java → test/jdk/java/lang/IO/Input.java

@@ -23,7 +23,7 @@
 
 import java.io.IOException;
 
-import static java.io.IO.readln;
+import static java.lang.IO.readln;
 
 public class Input {
 

test/jdk/java/io/IO/Methods.java → test/jdk/java/lang/IO/Methods.java

@@ -21,7 +21,7 @@
  * questions.
  */
 
-import static java.io.IO.*;
+import static java.lang.IO.*;
 
 public class Methods {
 

test/jdk/java/io/IO/Output.java → test/jdk/java/lang/IO/Output.java

@@ -21,7 +21,7 @@
  * questions.
  */
 
-import static java.io.IO.*;
+import static java.lang.IO.*;
 import java.util.function.Consumer;
 
 public class Output {