1 /*
   2  * Copyright (c) 2018, 2019, Oracle and/or its affiliates. All rights reserved.
   3  * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
   4  *
   5  * This code is free software; you can redistribute it and/or modify it
   6  * under the terms of the GNU General Public License version 2 only, as
   7  * published by the Free Software Foundation.
   8  *
   9  * This code is distributed in the hope that it will be useful, but WITHOUT
  10  * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
  11  * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License
  12  * version 2 for more details (a copy is included in the LICENSE file that
  13  * accompanied this code).
  14  *
  15  * You should have received a copy of the GNU General Public License version
  16  * 2 along with this work; if not, write to the Free Software Foundation,
  17  * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
  18  *
  19  * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
  20  * or visit www.oracle.com if you need additional information or have any
  21  * questions.
  22  */
  23 
  24 /*
  25  * @test
  26  * @bug 8206986
  27  * @summary Check fall through in switch expressions.
  28  * @compile --enable-preview -source ${jdk.version} ExpressionSwitchFallThrough.java
  29  * @run main/othervm --enable-preview ExpressionSwitchFallThrough
  30  */
  31 
  32 import java.util.Objects;
  33 import java.util.function.Function;
  34 
  35 public class ExpressionSwitchFallThrough {
  36     public static void main(String... args) {
  37         new ExpressionSwitchFallThrough().run();
  38     }
  39 
  40     private void run() {
  41         runTest(this::expression1);
  42         runTest(this::expression2);
  43     }
  44 
  45     private void runTest(Function<T, String> print) {
  46         check(T.A,  print, "ab");
  47         check(T.B,  print, "b");
  48         check(T.C,  print, "");
  49     }
  50 
  51     private String expression1(T t) {
  52         String help = "";
  53         return switch (t) {
  54             case A: help = "a";
  55             case B: help += "b";
  56             default: yield help;
  57         };
  58     }
  59 
  60     private String expression2(T t) {
  61         String help = "";
  62         return switch (t) {
  63             case A: help = "a";
  64             case B: help += "b";
  65             default: yield help;
  66         };
  67     }
  68 
  69     private void check(T t, Function<T, String> print, String expected) {
  70         String result = print.apply(t);
  71         if (!Objects.equals(result, expected)) {
  72             throw new AssertionError("Unexpected result: " + result);
  73         }
  74     }
  75 
  76     enum T {
  77         A, B, C;
  78     }
  79 }