8270490: Charset.forName() taking fallback default value

Reviewed-by: joehw, rriggs, serb, dfuchs

src/java.base/share/classes/java/io/Console.java

@@ -582,17 +582,12 @@ public final class Console implements Flushable
                 csname = GetPropertyAction.privilegedGetProperty("sun.stdout.encoding");
             }
             if (csname != null) {
-                try {
-                    cs = Charset.forName(csname);
-                } catch (Exception ignored) { }
+                cs = Charset.forName(csname, null);
             }
         }
         if (cs == null) {
-            try {
-                cs = Charset.forName(StaticProperty.nativeEncoding());
-            } catch (Exception ignored) {
-                cs = Charset.defaultCharset();
-            }
+            cs = Charset.forName(StaticProperty.nativeEncoding(),
+                    Charset.defaultCharset());
         }
 
         CHARSET = cs;

src/java.base/share/classes/java/nio/charset/Charset.java

@@ -527,6 +527,39 @@ public abstract class Charset
         throw new UnsupportedCharsetException(charsetName);
     }
 
+    /**
+     * Returns a charset object for the named charset. If the charset object
+     * for the named charset is not available or {@code charsetName} is not a
+     * legal charset name, then {@code fallback} is returned.
+     *
+     * @param  charsetName
+     *         The name of the requested charset; may be either
+     *         a canonical name or an alias
+     *
+     * @param  fallback
+     *         fallback charset in case the charset object for the named
+     *         charset is not available or {@code charsetName} is not a legal
+     *         charset name. May be {@code null}
+     *
+     * @return  A charset object for the named charset, or {@code fallback}
+     *          in case the charset object for the named charset is not
+     *          available or {@code charsetName} is not a legal charset name
+     *
+     * @throws  IllegalArgumentException
+     *          If the given {@code charsetName} is {@code null}
+     *
+     * @since 18
+     */
+    public static Charset forName(String charsetName,
+                                  Charset fallback) {
+        try {
+            Charset cs = lookup(charsetName);
+            return cs != null ? cs : fallback;
+        } catch (IllegalCharsetNameException icne) {
+            return fallback;
+        }
+    }
+
     // Fold charsets from the given iterator into the given map, ignoring
     // charsets whose names already have entries in the map.
     //

test/jdk/java/nio/charset/Charset/ForName.java

@@ -0,0 +1,73 @@
+/*
+ * Copyright (c) 2021, 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.
+ *
+ * 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.
+ */
+
+/* @test
+ * @summary Unit test for forName(String, Charset)
+ * @bug 8270490
+ * @modules jdk.charsets
+ * @run testng ForName
+ */
+
+import java.nio.charset.Charset;
+import java.nio.charset.IllegalCharsetNameException;
+import java.nio.charset.StandardCharsets;
+
+import org.testng.annotations.DataProvider;
+import org.testng.annotations.Test;
+import static org.testng.Assert.assertEquals;
+
+@Test
+public class ForName {
+
+    @DataProvider
+    Object[][] params() {
+        return new Object[][] {
+                {"UTF-8", null, StandardCharsets.UTF_8},
+                {"UTF-8", StandardCharsets.US_ASCII, StandardCharsets.UTF_8},
+                {"windows-31j", StandardCharsets.US_ASCII, Charset.forName("windows-31j")},
+                {"foo", StandardCharsets.US_ASCII, StandardCharsets.US_ASCII},
+                {"foo", null, null},
+                {"\u3042", null, null},
+                {"\u3042", StandardCharsets.UTF_8, StandardCharsets.UTF_8},
+        };
+    }
+
+    @DataProvider
+    Object[][] paramsIAE() {
+        return new Object[][] {
+                {null, null},
+                {null, StandardCharsets.UTF_8},
+        };
+    }
+
+    @Test(dataProvider="params")
+    public void testForName_2arg(String name, Charset fallback, Charset expected) throws Exception {
+        var cs = Charset.forName(name, fallback);
+        assertEquals(cs, expected);
+    }
+
+    @Test(dataProvider="paramsIAE", expectedExceptions=IllegalArgumentException.class)
+    public void testForName_2arg_IAE(String name, Charset fallback) throws Exception {
+        Charset.forName(name, fallback);
+    }
+}