fix #27 on newer java versions where reflection is restricted

java-api/src/java18/java/xyz/wagyourtail/jvmdg/j18/stub/java_base/J_I_PrintStream.java

@@ -1,21 +1,37 @@
 package xyz.wagyourtail.jvmdg.j18.stub.java_base;
 
+import xyz.wagyourtail.jvmdg.util.Utils;
 import xyz.wagyourtail.jvmdg.version.Stub;
 
 import java.io.OutputStreamWriter;
 import java.io.PrintStream;
+import java.lang.invoke.MethodHandle;
+import java.lang.invoke.MethodHandles;
 import java.lang.reflect.Field;
 import java.nio.charset.Charset;
 
 public class J_I_PrintStream {
+    private static final MethodHandles.Lookup IMPL_LOOKUP = Utils.getImplLookup();
+    private static final MethodHandle getCharOut;
+
+    static {
+        try {
+            getCharOut = IMPL_LOOKUP.findGetter(PrintStream.class, "charOut", OutputStreamWriter.class);
+        } catch (NoSuchFieldException | IllegalAccessException e) {
+            throw new RuntimeException(e);
+        }
+    }
 
     @Stub
-    public static Charset charset(PrintStream printStream) throws NoSuchFieldException, IllegalAccessException {
-        Field charOut = PrintStream.class.getDeclaredField("charOut");
-        charOut.setAccessible(true);
-        OutputStreamWriter writer = (OutputStreamWriter) charOut.get(printStream);
-        String encoding = writer.getEncoding();
-        return Charset.forName(encoding);
+    public static Charset charset(PrintStream printStream) {
+        try {
+            OutputStreamWriter writer = (OutputStreamWriter) getCharOut.invokeExact(printStream);
+            String encoding = writer.getEncoding();
+            return Charset.forName(encoding);
+        } catch (Throwable e) {
+            Utils.sneakyThrow(e);
+        }
+        return null;
     }
 
 }

testing/downgrade/src/main/java/xyz/wagyourtail/downgradetest/TestPrintWriter.java

@@ -9,7 +9,7 @@ public class TestPrintWriter {
 
 
     public static void main(String[] args) throws IOException {
-        PrintWriter out = new PrintWriter(System.out, false, StandardCharsets.UTF_8);
+        PrintWriter out = new PrintWriter(System.out, false, System.out.charset());
         out.println("Hello World!");
 
         var temp = Files.createTempFile("temp", "txt");