From 664c6108a5d0dadfc530aeeca9f478393b1e00d4 Mon Sep 17 00:00:00 2001
From: fszimnau <fabian.szimnau@ergo-life.com>
Date: Wed, 19 Nov 2025 13:57:28 +0100
Subject: [PATCH] Learn to work when run via jar instead of via .class file
 directly

---
 .../java/de/szimnau/zeitlaeufer/Main.java     | 47 +++++++++++++------
 1 file changed, 33 insertions(+), 14 deletions(-)

diff --git a/src/main/java/de/szimnau/zeitlaeufer/Main.java b/src/main/java/de/szimnau/zeitlaeufer/Main.java
index 85d1f01..0d78920 100644
--- a/src/main/java/de/szimnau/zeitlaeufer/Main.java
+++ b/src/main/java/de/szimnau/zeitlaeufer/Main.java
@@ -2,13 +2,17 @@ package de.szimnau.zeitlaeufer;
 
 import java.io.BufferedReader;
 import java.io.IOException;
-import java.io.InputStream;
 import java.io.InputStreamReader;
 import java.lang.reflect.InvocationTargetException;
+import java.lang.reflect.Method;
+import java.net.URL;
+import java.net.URLDecoder;
 import java.nio.charset.StandardCharsets;
 import java.util.*;
 import java.util.concurrent.atomic.AtomicInteger;
 import java.util.function.Function;
+import java.util.jar.JarEntry;
+import java.util.jar.JarFile;
 import java.util.stream.Collectors;
 
 import static de.szimnau.zeitlaeufer.tools.CommonTools.print;
@@ -27,26 +31,41 @@ public class Main {
 
    private static void askParametersAndRun() throws IOException, NoSuchMethodException, InvocationTargetException, IllegalAccessException {
       var br = new BufferedReader(new InputStreamReader(System.in, StandardCharsets.UTF_8));
-      Map<Integer, Class<?>> classes = getAllrelevantClasses();
+      SortedMap<Integer, Class<?>> classes = getAllrelevantClasses();
       String printedClasses = classes.entrySet().stream()
           .map(e -> e.getKey() + ": " + e.getValue().getCanonicalName().substring(e.getValue().getCanonicalName().lastIndexOf('.') + 1))
           .reduce("", (a, b) -> a + "\n" + b);
       print("Welcher Zeitläufer soll verwendet werden? " + printedClasses + "\n: ");
       var num = Integer.parseInt(br.readLine());
       Class<?> selectedClass = classes.get(num);
-      var mainMethod = selectedClass.getMethod("main", String[].class);
+      Method mainMethod = selectedClass.getMethod("main", String[].class);
       mainMethod.invoke(null, (Object) new String[0]);
    }
 
 
-   private static Map<Integer, Class<?>> getAllrelevantClasses() {
-      InputStream stream = ClassLoader.getSystemClassLoader()
-          .getResourceAsStream("de/szimnau/zeitlaeufer");
-      var br = new BufferedReader(new InputStreamReader(stream, StandardCharsets.UTF_8));
+   private static SortedMap<Integer, Class<?>> getAllrelevantClasses() {
+      ClassLoader classLoader = Thread.currentThread().getContextClassLoader();
+      List<String> fileNames = new ArrayList<>();
+      URL jarUrl = classLoader.getResource("de/szimnau/zeitlaeufer");
+      String path = jarUrl.getPath().split(":", 2)[1];
+      String cleanPath = path.substring(0, path.lastIndexOf('!'));
+      Enumeration<JarEntry> entries;
+      try (var jarFile = new JarFile(URLDecoder.decode(cleanPath, StandardCharsets.UTF_8))) {
+         entries = jarFile.entries();
+      } catch (IOException e) {
+         throw new RuntimeException(e);
+      }
+      while (entries.hasMoreElements()) {
+         JarEntry entry = entries.nextElement();
+         if (entry.isDirectory()) {
+            continue;
+         }
+         fileNames.add(entry.getName());
+      }
       var increment = new AtomicInteger();
       return Collections.unmodifiableSortedMap(new TreeMap<>(
-          br.lines()
-              .filter(line -> line.endsWith(".class") && !"Main.class".equals(line))
+          fileNames.stream()
+              .filter(line -> line.endsWith(".class") && !line.endsWith("module-info.class") && !line.endsWith("Main.class"))
               .sorted()
               .map(Main::getClass)
               .filter(Objects::nonNull)
@@ -61,23 +80,23 @@ public class Main {
 
 
    private static Class<?> getClass(String className) {
-      return getClassForName(className.substring(0, className.lastIndexOf('.')));
+      String classWithPath = className.replace("/", ".");
+      return getClassForName(classWithPath.substring(0, className.lastIndexOf('.')));
    }
 
 
    private static Class<?> getClassForName(String className) {
-      String fqnClassName = "de.szimnau.zeitlaeufer." + className;
       try {
-         return Class.forName(fqnClassName);
+         return Class.forName(className);
       } catch (ClassNotFoundException cnfe) {
-         println("ERROR: could not find Class for Name: de.szimnau.zeitlaeufer." + fqnClassName);
+         println("ERROR: could not find Class for Name: de.szimnau.zeitlaeufer." + className);
       }
       return null;
    }
 
 
    private static void parseParametersAndRun(String[] args) throws NoSuchMethodException, InvocationTargetException, IllegalAccessException {
-      Class<?> selectedClass = getClassForName(args[0]);
+      Class<?> selectedClass = getClassForName("de.szimnau.zeitlaeufer." + args[0]);
       if (selectedClass == null) {
          System.exit(1);
       }