Do not add a break after a throw

Fixes #785

Author: timtebeek

src/main/java/org/openrewrite/java/migrate/lang/NullCheckAsSwitchCase.java

@@ -154,11 +154,26 @@ private J.Case createCaseStatement(J.Switch aSwitch, Statement whenNull, J.Case
                 } else {
                     statements.add(whenNull);
                 }
+
+                // Check if the last statement is a throw statement
+                Statement lastStatement = null;
+                if (whenNull instanceof J.Block) {
+                    List<Statement> blockStatements = ((J.Block) whenNull).getStatements();
+                    if (!blockStatements.isEmpty()) {
+                        lastStatement = blockStatements.get(blockStatements.size() - 1);
+                    }
+                } else {
+                    lastStatement = whenNull;
+                }
+
                 StringBuilder template = new StringBuilder("switch(#{any()}) {\ncase null:");
                 for (int i = 1; i < statements.size(); i++) {
                     template.append("\n#{any()};");
                 }
-                template.append("\nbreak;\n}");
+                if (!(lastStatement instanceof J.Throw)) {
+                    template.append("\nbreak;");
+                }
+                template.append("\n}");
                 J.Switch switchWithNullCase = JavaTemplate.apply(
                         template.toString(),
                         new Cursor(getCursor(), aSwitch),

src/test/java/org/openrewrite/java/migrate/lang/NullCheckAsSwitchCaseTest.java

@@ -18,6 +18,7 @@
 import org.junit.jupiter.api.Nested;
 import org.junit.jupiter.api.Test;
 import org.openrewrite.DocumentExample;
+import org.openrewrite.Issue;
 import org.openrewrite.test.RecipeSpec;
 import org.openrewrite.test.RewriteTest;
 
@@ -926,4 +927,66 @@ void score(Suit obj) {
             );
         }
     }
+
+    @Issue("https://github.com/openrewrite/rewrite-migrate-java/issues/785")
+    @Test
+    void noBreakAfterThrow() {
+        rewriteRun(
+          java(
+            """
+              class Foo {
+                  String bar(String foo) {
+                      if (foo == null) {
+                          throw new RuntimeException("");
+                      }
+                      switch (foo) {
+                          case "hello":
+                              return "world";
+                          default:
+                              return "other";
+                      }
+                  }
+              }
+              """,
+            """
+              class Foo {
+                  String bar(String foo) {
+                      switch (foo) {
+                          case null:
+                              throw new RuntimeException("");
+                          case "hello":
+                              return "world";
+                          default:
+                              return "other";
+                      }
+                  }
+              }
+              """
+          )
+        );
+    }
+
+    @Issue("https://github.com/openrewrite/rewrite-migrate-java/issues/785")
+    @Test
+    void noChangeOnReturn() {
+        rewriteRun(
+          java(
+            """
+              class Foo {
+                  String bar(String foo) {
+                      if (foo == null) {
+                          return "";
+                      }
+                      switch (foo) {
+                          case "hello":
+                              return "world";
+                          default:
+                              return "other";
+                      }
+                  }
+              }
+              """
+          )
+        );
+    }
 }