add demo for class file

src/main/java/Main.java

@@ -0,0 +1,7 @@
+package main.java;
+
+public class Main {
+    public static void main(String[] args) {
+        System.out.println("Hello, World!");
+    }
+}

src/main/java/VarHandlerDemoRunner.java

@@ -0,0 +1,41 @@
+package main.java;
+
+import jvm.VarHandleDemo;
+
+import java.lang.invoke.MethodHandles;
+import java.lang.invoke.VarHandle;
+
+public class VarHandlerDemoRunner {
+
+    public static void main(String[] args) throws IllegalAccessException, NoSuchFieldException {
+        VarHandleDemo instance = new VarHandleDemo();
+
+        //access private field
+        VarHandle varHandle = MethodHandles
+                .privateLookupIn(VarHandleDemo.class, MethodHandles.lookup())
+                .findVarHandle(VarHandleDemo.class, "privateVar", int.class);
+        varHandle.set(instance, 33);
+        System.out.println(instance);
+
+        //access protected field
+        VarHandle varHandle2 = MethodHandles
+                .privateLookupIn(VarHandleDemo.class,MethodHandles.lookup())
+                .findVarHandle(VarHandleDemo.class, "protectedVar", int.class);
+        varHandle2.set(instance, 22);
+        System.out.println(instance);
+
+        //access public field
+        VarHandle varHandle3 = MethodHandles.lookup()
+                .in(VarHandleDemo.class)
+                .findVarHandle(VarHandleDemo.class, "publicVar", int.class);
+        varHandle3.set(instance, 11);
+        System.out.println(instance);
+
+        //access array
+        VarHandle varHandle4 = MethodHandles.arrayElementVarHandle(int[].class);
+        varHandle4.compareAndSet(instance.publicArrayData, 0, 1,11);
+        varHandle4.compareAndSet(instance.publicArrayData, 1, 2,22);
+        varHandle4.compareAndSet(instance.publicArrayData, 2, 3,33);
+        System.out.println(instance);
+    }
+}

src/main/java/jvm/classfile/TestClass.java

@@ -0,0 +1,13 @@
+package jvm.classfile;
+
+/**
+ * Compile for examine class file
+ */
+public class TestClass {
+
+    private int m;
+
+    public int inc() {
+        return m+1;
+    }
+}

src/main/java/jvm/classfile/TestClassK.kt

@@ -0,0 +1,9 @@
+package jvm.classfile
+
+class TestClassK {
+    private var m: Int = 0;
+
+    fun inc() : Int {
+        return m + 1
+    }
+}