code: //non-compiled with javac: Compilable with Java19
  package com.puppycrawl.tools.checkstyle.grammar.java19;
  
  import java.util.ArrayList;
  import java.util.LinkedList;
  import java.util.List;
  import java.util.Set;
  
  public class InputJava19PatternsInSwitchLabels {
      static void m1(Object o) {
          // patterns in switch are guarded by 'when'
          switch (o) {
              case Integer i when i >= 0 -> System.out.println(i);
              case Integer i -> System.out.println(i << 1);
              default -> throw new IllegalStateException(
                      "Unexpected value: " + o);
          }
      }
  
      static <T> void m2(Object o) {
          // Note that pattern variable cannot be cast to generic type
          switch (o) {
              case List list1 when (list1.size() >= 0
                      && list1.size() < 10) || list1.equals(new ArrayList<>()) ->
                      System.out.println(list1);
              case List list2 when (list2.size() >= 0
                      && list2.size() < 20) || list2.equals(new LinkedList()) ->
                      System.out.println("list2");
              case List list3 when list3.size() >= 0
                      && list3.size() < 45 || list3.equals(new LinkedList()) ->
                      System.out.println("list3");
              case Set set when "test".equals(set.toString()) ->
                      System.out.println(set);
              default -> throw new IllegalStateException(
                      "Unexpected value: " + o);
          }
      }
  
      static String m3(Object o) {
          // patterns in switch are guarded by 'when'
          return switch (o) {
              case List list1 when list1.size() >= 0
                      || list1.size() < 20 -> {
                  yield "list1!";
              }
              case List list1 when list1.size() >= 0
                      || list1.size() < 50 -> "list1!";
  
              case Integer i1 when i1 < 3 && i1 > 0 -> "small integer!";
              case Integer i2 when i2 < 0 || i2 < -5 -> "small negative integer!";
              case A a when a instanceof B b && b.f == 2 ->
                      "it's a 'b'!";
              case A a when !(a instanceof B b) || a instanceof B  b1 && b.f < 0 ->
                      "it's not a 'b' or it's a negative 'b'";
              case A a when !(a instanceof B b) || a instanceof B b2 && b.f < -5 ->
                      "it's not a 'b' or it's a negative 'b'...";
              case null -> "it's null!";
              default -> throw new IllegalStateException(
                      "Unexpected value: " + o);
          };
      }
  
  }
  
  sealed class A permits B {
  
  }
  
  non-sealed class B extends A {
      public int f = 2;
  }
  