From 224780a84dbae2fc1adf3d948bb2942adb1f9b54 Mon Sep 17 00:00:00 2001
From: Mark Vainomaa <mikroskeem@mikroskeem.eu>
Date: Fri, 24 Feb 2017 15:45:00 +0200
Subject: [PATCH] Add method to construct classes using reflection

---
 .../eu/mikroskeem/utils/reflect/Reflect.java  | 37 +++++++++++++++++++
 .../test/reflect/DifferentConstructors.java   |  6 +++
 .../utils/test/reflect/TestReflect.java       | 16 ++++++++
 3 files changed, 59 insertions(+)
 create mode 100644 Reflect/src/test/java/eu/mikroskeem/utils/test/reflect/DifferentConstructors.java

diff --git a/Reflect/src/main/java/eu/mikroskeem/utils/reflect/Reflect.java b/Reflect/src/main/java/eu/mikroskeem/utils/reflect/Reflect.java
index f941d1a..b84da86 100644
--- a/Reflect/src/main/java/eu/mikroskeem/utils/reflect/Reflect.java
+++ b/Reflect/src/main/java/eu/mikroskeem/utils/reflect/Reflect.java
@@ -1,11 +1,16 @@
 package eu.mikroskeem.utils.reflect;
 
+import lombok.Getter;
+import lombok.RequiredArgsConstructor;
 import org.jetbrains.annotations.NotNull;
 import org.jetbrains.annotations.Nullable;
 
+import java.lang.reflect.Constructor;
 import java.lang.reflect.Field;
 import java.lang.reflect.InvocationTargetException;
 import java.lang.reflect.Method;
+import java.util.stream.Collectors;
+import java.util.stream.Stream;
 
 /**
  * Reflection utils
@@ -39,6 +44,27 @@ public class Reflect {
         return getClass(clazz) != null;
     }
 
+    /**
+     * Construct class with arguments. Note: primitive types aren't supported
+     *
+     *
+     * @param clazz Class to construct
+     * @param arguments Class constructor arguments
+     * @return Class instance or null
+     */
+    public static Object fastConstruct(@NotNull Class<?> clazz, TypeWrapper... arguments){
+        try {
+            Class<?>[] tArgs = Stream.of(arguments).map(TypeWrapper::getType).collect(Collectors.toList()).toArray(new Class[0]);
+            Object[] args = Stream.of(arguments).map(TypeWrapper::getValue).collect(Collectors.toList()).toArray();
+            Constructor constructor = clazz.getDeclaredConstructor(tArgs);
+            constructor.setAccessible(true);
+            return constructor.newInstance(args);
+        } catch (NoSuchMethodException|InstantiationException|IllegalAccessException|InvocationTargetException e){
+            e.printStackTrace();
+            return null;
+        }
+    }
+
     /**
      * Get declared class method (public,protected,private)
      *
@@ -188,4 +214,15 @@ public class Reflect {
         }
         return null;
     }
+
+
+    /**
+     * Type/value wrapper for reflective constructing
+     */
+    @RequiredArgsConstructor
+    @Getter
+    public static class TypeWrapper {
+        private final Object value;
+        private final Class<?> type;
+    }
 }
diff --git a/Reflect/src/test/java/eu/mikroskeem/utils/test/reflect/DifferentConstructors.java b/Reflect/src/test/java/eu/mikroskeem/utils/test/reflect/DifferentConstructors.java
new file mode 100644
index 0000000..1ed9a0a
--- /dev/null
+++ b/Reflect/src/test/java/eu/mikroskeem/utils/test/reflect/DifferentConstructors.java
@@ -0,0 +1,6 @@
+package eu.mikroskeem.utils.test.reflect;
+
+public class DifferentConstructors {
+    public DifferentConstructors(Integer a, Integer b, int c, boolean d){}
+    private DifferentConstructors(String foo, String bar){}
+}
diff --git a/Reflect/src/test/java/eu/mikroskeem/utils/test/reflect/TestReflect.java b/Reflect/src/test/java/eu/mikroskeem/utils/test/reflect/TestReflect.java
index 8fc327a..133a76c 100644
--- a/Reflect/src/test/java/eu/mikroskeem/utils/test/reflect/TestReflect.java
+++ b/Reflect/src/test/java/eu/mikroskeem/utils/test/reflect/TestReflect.java
@@ -112,4 +112,20 @@ public class TestReflect {
         Assert.assertTrue(Reflect.classExists(className));
         Assert.assertEquals("hey", testFieldContent);
     }
+
+    @Test
+    public void testConstructing(){
+        Assert.assertNotNull(Reflect.fastConstruct(
+                DifferentConstructors.class,
+                new Reflect.TypeWrapper(1, Integer.class),
+                new Reflect.TypeWrapper(2, Integer.class),
+                new Reflect.TypeWrapper(3, int.class),
+                new Reflect.TypeWrapper(true, boolean.class)
+        ));
+        Assert.assertNotNull(Reflect.fastConstruct(
+                DifferentConstructors.class,
+                new Reflect.TypeWrapper("kek", String.class),
+                new Reflect.TypeWrapper("kek", String.class)
+        ));
+    }
 }