chore: improve readability of method retrieval

Bukkit/src/main/java/com/plotsquared/bukkit/schematic/StateWrapperSpigot.java

@@ -18,6 +18,7 @@
  */
 package com.plotsquared.bukkit.schematic;
 
+import com.plotsquared.core.util.ReflectionHelper;
 import com.plotsquared.core.util.ReflectionUtils;
 import com.sk89q.jnbt.CompoundTag;
 import com.sk89q.worldedit.bukkit.WorldEditPlugin;
@@ -236,13 +237,11 @@ final class StateWrapperSpigot implements StateWrapper {
 
     private static MethodHandle findCraftBlockEntityStateUpdateMethodHandle(Class<?> craftBlockEntityStateClass) throws
             NoSuchMethodException, IllegalAccessException {
-        for (final Method method : craftBlockEntityStateClass.getMethods()) {
+        return LOOKUP.unreflect(ReflectionHelper.findMethod(
-            if (method.getReturnType().equals(Boolean.TYPE) && method.getParameterCount() == 2 &&
+                craftBlockEntityStateClass,
-                    method.getParameterTypes()[0] == Boolean.TYPE && method.getParameterTypes()[1] == Boolean.TYPE) {
+                MethodType.methodType(Boolean.TYPE, Boolean.TYPE, Boolean.TYPE),
-                return LOOKUP.unreflect(method);
+                Modifier.PUBLIC
-            }
+        ).orElseThrow(() -> new NoSuchMethodException("Couldn't lookup CraftBlockEntityState#update(boolean, boolean) boolean")));
-        }
-        throw new NoSuchMethodException("Couldn't find method for #update(boolean, boolean) in " + craftBlockEntityStateClass.getName());
     }
 
     private static MethodHandle findCraftBlockEntityStateSnapshotMethodHandle(Class<?> craftBlockEntityStateClass) throws
@@ -254,13 +253,11 @@ final class StateWrapperSpigot implements StateWrapper {
 
     private static MethodHandle findSignBlockEntitySetTextMethodHandle(Class<?> signBlockEntity, Class<?> signText) throws
             NoSuchMethodException, IllegalAccessException {
-        for (final Method method : signBlockEntity.getMethods()) {
+        return LOOKUP.unreflect(ReflectionHelper.findMethod(
-            if (method.getReturnType() == Boolean.TYPE && method.getParameterCount() == 2
+                signBlockEntity,
-                    && method.getParameterTypes()[0] == signText && method.getParameterTypes()[1] == Boolean.TYPE) {
+                MethodType.methodType(Boolean.TYPE, signText, Boolean.TYPE),
-                return LOOKUP.unreflect(method);
+                Modifier.PUBLIC
-            }
+        ).orElseThrow(() -> new NoSuchMethodException("Couldn't lookup SignBlockEntity#setText(SignText, boolean) boolean")));
-        }
-        throw new NoSuchMethodException("Couldn't lookup SignBlockEntity#setText(SignText, boolean) boolean");
     }
 
 }

Core/src/main/java/com/plotsquared/core/util/ReflectionHelper.java

@@ -0,0 +1,76 @@
+/*
+ * PlotSquared, a land and world management plugin for Minecraft.
+ * Copyright (C) IntellectualSites <https://intellectualsites.com>
+ * Copyright (C) IntellectualSites team and contributors
+ *
+ * This program is free software: you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation, either version 3 of the License, or
+ * (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program.  If not, see <https://www.gnu.org/licenses/>.
+ */
+package com.plotsquared.core.util;
+
+import org.jetbrains.annotations.ApiStatus;
+
+import java.lang.invoke.MethodHandles;
+import java.lang.invoke.MethodType;
+import java.lang.reflect.Method;
+import java.util.Optional;
+
+@ApiStatus.Internal
+public final class ReflectionHelper {
+
+    /**
+     * Find a (declared) method with an unknown or potentially obfuscated name by its signature and optional modifiers.
+     * <br>
+     * The method - if private - is not made accessible. Either call {@link Method#setAccessible(boolean)} or
+     * use a {@link java.lang.invoke.MethodHandles.Lookup#privateLookupIn(Class, MethodHandles.Lookup) private lookup}.
+     *
+     * @param holder    The class providing the method.
+     * @param signature The signature of the method, identified by parameter types and the return type.
+     * @param modifiers All possible modifiers of the method that should be validated.
+     * @return The method, if one has been found. Otherwise, an empty Optional.
+     * @throws RuntimeException if multiple matching methods have been found.
+     * @see java.lang.reflect.Modifier
+     */
+    public static Optional<Method> findMethod(Class<?> holder, MethodType signature, int... modifiers) {
+        Method found = null;
+        outer:
+        for (final Method method : holder.getDeclaredMethods()) {
+            if (method.getParameterCount() != signature.parameterCount()) {
+                continue;
+            }
+            if (!signature.returnType().isAssignableFrom(method.getReturnType())) {
+                continue;
+            }
+
+            for (final int modifier : modifiers) {
+                if ((method.getModifiers() & modifier) == 0) {
+                    continue outer;
+                }
+            }
+
+            Class<?>[] parameterTypes = signature.parameterArray();
+            for (int i = 0; i < parameterTypes.length; i++) {
+                // validate expected parameter is either the same type or subtype of actual parameter
+                if (!parameterTypes[i].isAssignableFrom(method.getParameterTypes()[i])) {
+                    continue outer;
+                }
+            }
+            if (found != null) {
+                throw new RuntimeException("Found ambiguous method by selector: " + method + " vs " + found);
+            }
+            found = method;
+        }
+        return Optional.ofNullable(found);
+    }
+
+}

Core/src/test/java/com/plotsquared/core/util/ReflectionHelperTest.java

@@ -0,0 +1,79 @@
+/*
+ * PlotSquared, a land and world management plugin for Minecraft.
+ * Copyright (C) IntellectualSites <https://intellectualsites.com>
+ * Copyright (C) IntellectualSites team and contributors
+ *
+ * This program is free software: you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation, either version 3 of the License, or
+ * (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program.  If not, see <https://www.gnu.org/licenses/>.
+ */
+package com.plotsquared.core.util;
+
+import org.junit.jupiter.api.Test;
+
+import java.lang.invoke.MethodType;
+import java.lang.reflect.Modifier;
+import java.util.Collection;
+
+import static org.junit.jupiter.api.Assertions.assertEquals;
+import static org.junit.jupiter.api.Assertions.assertThrows;
+
+class ReflectionHelperTest {
+
+    @Test
+    void findMethod() throws NoSuchMethodException {
+        assertThrows(
+                RuntimeException.class, () ->
+                        ReflectionHelper.findMethod(MethodTesterClass.class, MethodType.methodType(String.class))
+        );
+        assertEquals(
+                MethodTesterClass.class.getMethod("methodThree"),
+                ReflectionHelper.findMethod(MethodTesterClass.class, MethodType.methodType(String.class), Modifier.PUBLIC)
+                        .orElse(null)
+        );
+        assertEquals(
+                MethodTesterClass.class.getDeclaredMethod("methodFour", String.class, Collection.class),
+                ReflectionHelper.findMethod(MethodTesterClass.class, MethodType.methodType(
+                        String.class, String.class, Collection.class
+                )).orElse(null)
+        );
+        // check that helper allows super classes of parameters when searching
+        assertEquals(
+                MethodTesterClass.class.getDeclaredMethod("methodFour", String.class, Collection.class),
+                ReflectionHelper.findMethod(MethodTesterClass.class, MethodType.methodType(
+                        String.class, String.class, Object.class
+                )).orElse(null)
+        );
+    }
+
+    @SuppressWarnings("unused")
+    private static class MethodTesterClass {
+
+        private static String methodOne() {
+            return "";
+        }
+
+        private static String methodTwo() {
+            return "";
+        }
+
+        public static String methodThree() {
+            return "";
+        }
+
+        protected static String methodFour(String param, Collection<String> paramList) {
+            return "";
+        }
+
+    }
+
+}