Add java22 samples from PMD

Author: adangel

.github/workflows/build.yml

@@ -8,7 +8,7 @@ jobs:
       - uses: actions/setup-java@v3
         with:
           distribution: 'temurin'
-          java-version: '21'
+          java-version: '22-ea'
           cache: 'maven'
       - name: Build with Maven
         run: ./mvnw --show-version --no-transfer-progress --errors --batch-mode package

java-regression-tests-1.0.0-SNAPSHOT.jar

@@ -7,11 +7,11 @@
     <packaging>jar</packaging>
 
     <properties>
-        <maven.compiler.release>21</maven.compiler.release>
+        <maven.compiler.release>22</maven.compiler.release>
         <project.build.sourceEncoding>UTF-8</project.build.sourceEncoding>
         <!-- fixing the build timestamp of the jar so that the jar file only changes, if content changes.
              the actual timestamp is irrelevant. -->
-        <project.build.outputTimestamp>2022-09-26T17:00:00Z</project.build.outputTimestamp>
+        <project.build.outputTimestamp>1980-01-01T12:00:00Z</project.build.outputTimestamp>
     </properties>
 
     <build>

pom.xml

@@ -0,0 +1,122 @@
+// SPDX-License-Identifier: BSD-3-Clause
+package net.sourceforge.pmd.java.regression.tests.java22;
+
+import java.util.ArrayDeque;
+import java.util.List;
+import java.util.Queue;
+import java.util.stream.Collectors;
+
+/**
+ * @see <a href="https://openjdk.org/jeps/443">JEP 443: Unnamed Patterns and Variables (Preview)</a> (Java 21)
+ * @see <a href="https://openjdk.org/jeps/456">JEP 456: Unnamed Variables & Patterns</a> (Java 22)
+ */
+class Jep456_UnamedPatternsAndVariables {
+    record Point(int x, int y) { }
+    enum Color { RED, GREEN, BLUE }
+    record ColoredPoint(Point p, Color c) { }
+
+    void unnamedPatterns1() {
+        ColoredPoint r = new ColoredPoint(new Point(3,4), Color.GREEN);
+
+        if (r instanceof ColoredPoint(Point p, Color _)) {
+            System.out.println(p.x() + " " + p.y());
+        }
+
+        if (r instanceof ColoredPoint(Point(int x, int y), _)) {
+            System.out.println(x + " " + y);
+        }
+    }
+
+    sealed abstract class Ball permits RedBall, BlueBall, GreenBall { }
+    final  class RedBall   extends Ball { }
+    final  class BlueBall  extends Ball { }
+    final  class GreenBall extends Ball { }
+
+    record Box<T extends Ball>(T content) { }
+
+    void unnamedPatterns2() {
+        Box<? extends Ball> b = new Box<>(new RedBall());
+        switch (b) {
+            case Box(RedBall   _) -> processBox(b);
+            case Box(BlueBall  _) -> processBox(b);
+            case Box(GreenBall _) -> stopProcessing();
+        }
+
+        switch (b) {
+            case Box(RedBall _), Box(BlueBall _) -> processBox(b);
+            case Box(GreenBall _)                -> stopProcessing();
+            case Box(_)                          -> pickAnotherBox();
+        }
+
+        int x = 42;
+        switch (b) {
+            // multiple patterns guarded by one guard
+            case Box(RedBall _), Box(BlueBall _) when x == 42 -> processBox(b);
+            case Box(_)                          -> pickAnotherBox();
+        }
+    }
+
+    private void processBox(Box<? extends Ball> b) {}
+    private void stopProcessing() {}
+    private void pickAnotherBox() {}
+
+    class Order {}
+    private static final int LIMIT = 10;
+    private int sideEffect() {
+        return 0;
+    }
+
+    void unnamedVariables(List<Order> orders) {
+        int total = 0;
+        for (Order _ : orders) {
+            if (total < LIMIT) {
+                total++;
+            }
+        }
+        System.out.println("total: " + total);
+
+        for (int i = 0, _ = sideEffect(); i < 10; i++) {
+            System.out.println(i);
+        }
+
+        Queue<Integer> q = new ArrayDeque<>(); // x1, y1, z1, x2, y2, z2 ..
+        while (q.size() >= 3) {
+            int x = q.remove();
+            int y = q.remove();
+            int _ = q.remove(); // z is unused
+            Point p = new Point(x, y);
+        }
+        while (q.size() >= 3) {
+            var x = q.remove();
+            var _ = q.remove();
+            var _ = q.remove();
+            Point p = new Point(x, 0);
+        }
+    }
+
+    static class ScopedContext implements AutoCloseable {
+        @Override
+        public void close() { }
+        public static ScopedContext acquire() {
+            return new ScopedContext();
+        }
+    }
+
+    void unusedVariables2() {
+        try (var _ = ScopedContext.acquire()) {
+            //... acquiredContext not used ...
+        }
+
+        String s = "123";
+        try {
+            int i = Integer.parseInt(s);
+            System.out.println(i);
+        } catch (NumberFormatException _) {
+            System.out.println("Bad number: " + s);
+        } catch (Exception _) {
+            System.out.println("error...");
+        }
+
+        List.of("a", "b").stream().collect(Collectors.toMap(String::toUpperCase, _ -> "NO_DATA"));
+    }
+}