diff --git a/c/memory_allocator.c b/c/memory_allocator.c
index 33a8c30..d96b4e2 100644
--- a/c/memory_allocator.c
+++ b/c/memory_allocator.c
@@ -142,6 +142,21 @@ void memory_iterate_allocated(memory_iterate_func_t func)
   }
 }
 
+int32_t memory_count_free_memory()
+{
+  int sum = 0;
+  for (int i = 0; i < free_list_length; i++) {
+    if (free_list[i] == 0)
+      sum += 1;
+  }
+  return sum * block_size;
+}
+
+int32_t memory_count_total_memory()
+{
+  return (sizeof (memory));
+}
+
 #if 0
 int main()
 {
diff --git a/c/memory_allocator.h b/c/memory_allocator.h
index d65829e..9fac3e3 100644
--- a/c/memory_allocator.h
+++ b/c/memory_allocator.h
@@ -8,3 +8,5 @@ void memory_free(void * p);
 bool memory_is_allocated(void * p);
 typedef void (* memory_iterate_func_t)(void * address);
 void memory_iterate_allocated(memory_iterate_func_t func);
+int32_t memory_count_free_memory();
+int32_t memory_count_total_memory();
diff --git a/c/native.c b/c/native.c
index a1374f1..1d0f22c 100644
--- a/c/native.c
+++ b/c/native.c
@@ -9,6 +9,7 @@
 #include "native/memory.h"
 #include "native/object.h"
 #include "native/printstream.h"
+#include "native/runtime.h"
 
 typedef void (* native_func_t)(struct vm * vm, uint32_t * args);
 
@@ -134,6 +135,24 @@ const static struct native_method native_method[] = {
     .method_descriptor = "()I",
     .func = native_java_lang_object_hashcode_1,
   },
+  {
+    .class_name = "java/lang/Runtime",
+    .method_name = "_freeMemory",
+    .method_descriptor = "()I",
+    .func = native_java_lang_runtime_freememory_0,
+  },
+  {
+    .class_name = "java/lang/Runtime",
+    .method_name = "_gc",
+    .method_descriptor = "()V",
+    .func = native_java_lang_runtime_gc_0,
+  },
+  {
+    .class_name = "java/lang/Runtime",
+    .method_name = "_totalMemory",
+    .method_descriptor = "()I",
+    .func = native_java_lang_runtime_totalmemory_0,
+  },
 };
 
 struct hash_table_entry * native_init_hash_table(int * hash_table_length)
diff --git a/c/native/runtime.c b/c/native/runtime.c
new file mode 100644
index 0000000..5d752ae
--- /dev/null
+++ b/c/native/runtime.c
@@ -0,0 +1,20 @@
+#include "runtime.h"
+#include "memory_allocator.h"
+#include "gc.h"
+
+void native_java_lang_runtime_freememory_0(struct vm * vm, uint32_t * args)
+{
+  int32_t count = memory_count_free_memory();
+  operand_stack_push_u32(vm->current_frame, count);
+}
+
+void native_java_lang_runtime_gc_0(struct vm * vm, uint32_t * args)
+{
+  gc_run(vm);
+}
+
+void native_java_lang_runtime_totalmemory_0(struct vm * vm, uint32_t * args)
+{
+  int32_t count = memory_count_total_memory();
+  operand_stack_push_u32(vm->current_frame, count);
+}
diff --git a/c/native/runtime.h b/c/native/runtime.h
new file mode 100644
index 0000000..d0edbab
--- /dev/null
+++ b/c/native/runtime.h
@@ -0,0 +1,9 @@
+#pragma once
+
+#include <stdint.h>
+
+#include "frame.h"
+
+void native_java_lang_runtime_freememory_0(struct vm * vm, uint32_t * args);
+void native_java_lang_runtime_gc_0(struct vm * vm, uint32_t * args);
+void native_java_lang_runtime_totalmemory_0(struct vm * vm, uint32_t * args);
diff --git a/classes/java/lang/Integer.java b/classes/java/lang/Integer.java
index be45d06..17f116b 100644
--- a/classes/java/lang/Integer.java
+++ b/classes/java/lang/Integer.java
@@ -2,7 +2,6 @@ package java.lang;
 
 import java.lang.DecimalDigits;
 
-
 public final class Integer
     extends Number
     implements Comparable<Integer> {
diff --git a/classes/java/lang/Long.java b/classes/java/lang/Long.java
index 13fc6a9..d48e224 100644
--- a/classes/java/lang/Long.java
+++ b/classes/java/lang/Long.java
@@ -2,7 +2,17 @@ package java.lang;
 
 import java.lang.DecimalDigits;
 
-public class Long {
+
+public final class Long
+//    extends Number
+//    implements Comparable<Long> {
+{
+    public static final long MAX_VALUE = 9223372036854775807L;
+
+    public static final long MIN_VALUE = -9223372036854775808L;
+
+    public static final int SIZE = 64;
+
     public static int stringSize(long n) {
         int sign_digits = 0;
         if (n < 0) {
diff --git a/classes/java/lang/Runtime.java b/classes/java/lang/Runtime.java
new file mode 100644
index 0000000..7c0f1cf
--- /dev/null
+++ b/classes/java/lang/Runtime.java
@@ -0,0 +1,38 @@
+package java.lang;
+
+public class Runtime {
+    private static final Runtime runtime;
+
+    private Runtime() {
+    }
+
+    static {
+        runtime = new Runtime();
+    }
+
+    private static native int _freeMemory();
+
+    public long freeMemory() {
+        return _freeMemory();
+    }
+
+    private static native void _gc();
+
+    public void gc() {
+        _gc();
+    }
+
+    public static Runtime getRuntime() {
+        return runtime;
+    }
+
+    public long maxMemory() {
+        return Long.MAX_VALUE;
+    }
+
+    private static native int _totalMemory();
+
+    public long totalMemory() {
+        return _totalMemory();
+    }
+}
diff --git a/java.mk b/java.mk
index c026a30..51b4fa4 100644
--- a/java.mk
+++ b/java.mk
@@ -27,6 +27,7 @@ OBJ = \
 	c/native/memory.o \
 	c/native/object.o \
 	c/native/printstream.o \
+	c/native/runtime.o \
 	c/parse.o \
 	c/parse_type.o \
 	c/printf.o \