diff --git a/src/main/kotlin/dex/ShortyDescriptor.kt b/src/main/kotlin/dex/ShortyDescriptor.kt
index ae65ce9..f5ab00f 100644
--- a/src/main/kotlin/dex/ShortyDescriptor.kt
+++ b/src/main/kotlin/dex/ShortyDescriptor.kt
@@ -8,7 +8,7 @@ data class ShortyDescriptor(val shorty: String) {
         buildString {
             append(names[returnType] ?: returnType)
             append("(")
-            append(parameterTypes.joinToString("") { names[it] ?: it })
+            append(parameterTypes.joinToString(",") { names[it] ?: it })
             append(")")
         }
     }
diff --git a/src/main/kotlin/vm/Environment.kt b/src/main/kotlin/vm/Environment.kt
index 7b506ef..d49f52e 100644
--- a/src/main/kotlin/vm/Environment.kt
+++ b/src/main/kotlin/vm/Environment.kt
@@ -1,6 +1,7 @@
 package com.yhs0602.vm
 
 import com.yhs0602.dex.*
+import com.yhs0602.vm.classloader.DexClassLoader
 import com.yhs0602.vm.instance.DictionaryBackedInstance
 import com.yhs0602.vm.instance.MockedInstance
 import com.yhs0602.vm.instance.unmarshalArgument
@@ -59,6 +60,7 @@ class Environment(
     private val staticFields = mutableMapOf<Pair<TypeId, Int>, Array<RegisterValue>>()
     private val initializedClasses: MutableSet<TypeId> = mutableSetOf()
     private val typeIdToCustomClass: MutableMap<TypeId, Class<*>> = mutableMapOf()
+    private val classLoader = DexClassLoader(dexFiles, mockedClasses)
 
     init {
         dexFiles.forEach { dexFile ->
diff --git a/src/main/kotlin/vm/classloader/DescriptorExtensions.kt b/src/main/kotlin/vm/classloader/DescriptorExtensions.kt
index b1c2034..8d979ef 100644
--- a/src/main/kotlin/vm/classloader/DescriptorExtensions.kt
+++ b/src/main/kotlin/vm/classloader/DescriptorExtensions.kt
@@ -61,7 +61,8 @@ fun Method.methodTableEntry(): MethodTableEntry {
             parameters = this@methodTableEntry.parameterTypes.map {
                 TypeId(it.descriptorString())
             }
-        }
+        },
+        method = this
     )
 }
 
@@ -85,6 +86,7 @@ fun Constructor<*>.methodTableEntry(): MethodTableEntry {
             parameters = this@methodTableEntry.parameterTypes.map {
                 TypeId(it.descriptorString())
             }
-        }
+        },
+        null
     )
 }
diff --git a/src/main/kotlin/vm/classloader/DexClassLoader.kt b/src/main/kotlin/vm/classloader/DexClassLoader.kt
index 0eeaff6..b85b4da 100644
--- a/src/main/kotlin/vm/classloader/DexClassLoader.kt
+++ b/src/main/kotlin/vm/classloader/DexClassLoader.kt
@@ -62,13 +62,15 @@ class DexClassLoader(
         }
         val superClassTypeId = parsedClass.classDef.superClassTypeId
         val superClassType = if (superClassTypeId != null) {
-            loadedTypes[superClassTypeId] ?: error("Superclass ${superClassTypeId.descriptor} not loaded")
+            loadedTypes[superClassTypeId] ?: error(
+                "Superclass ${superClassTypeId.descriptor} for ${parsedClass.classDef.typeId} not loaded"
+            )
         } else {
             null
         }
         val interfaces = parsedClass.classDef.interfaces
         val interfaceTypes = interfaces.map {
-            loadedTypes[it] ?: error("Interface ${it.descriptor} not loaded")
+            loadedTypes[it] ?: error("Interface ${it.descriptor} for ${parsedClass.classDef.typeId} not loaded")
         }
         val loadedType = DexDefinedType(
             parsedClass,
diff --git a/src/main/kotlin/vm/classloader/DexDefinedType.kt b/src/main/kotlin/vm/classloader/DexDefinedType.kt
index 4c5ced8..605f238 100644
--- a/src/main/kotlin/vm/classloader/DexDefinedType.kt
+++ b/src/main/kotlin/vm/classloader/DexDefinedType.kt
@@ -3,7 +3,6 @@ package com.yhs0602.vm.classloader
 import com.yhs0602.dex.ParsedClass
 import com.yhs0602.vm.MethodWrapper
 import net.bytebuddy.ByteBuddy
-import net.bytebuddy.dynamic.DynamicType
 import net.bytebuddy.dynamic.loading.ClassLoadingStrategy
 import net.bytebuddy.implementation.MethodDelegation
 
@@ -23,6 +22,7 @@ class DexDefinedType(
     private val _virtualTable: MutableMap<MethodTableEntry, MethodTableEntry> = mutableMapOf()
     override val methods = mutableMapOf<MethodTableEntry, MethodWrapper>()
     override val constructors = mutableMapOf<MethodTableEntry, MethodWrapper>()
+    override val staticMethods = mutableMapOf<MethodTableEntry, MethodWrapper>()
     override val clazz by lazy {
         makeClazz()
     }
@@ -40,20 +40,26 @@ class DexDefinedType(
                 val methodId = method.methodId
                 val methodTableEntry = MethodTableEntry(
                     methodId.name,
-                    methodId.protoId
+                    methodId.protoId,
+                    null
                 )
                 _virtualTable[methodTableEntry] = methodTableEntry
+                methods[methodTableEntry] = MethodWrapper.Encoded(method)
             }
             for (method in it.directMethods) {
                 val methodId = method.methodId
                 val methodTableEntry = MethodTableEntry(
                     methodId.name,
-                    methodId.protoId
+                    methodId.protoId,
+                    null
                 )
-                if (method.accessFlags.isConstructor) {
+                if (method.accessFlags.isStatic) {
+                    staticMethods[methodTableEntry] = MethodWrapper.Encoded(method)
+                } else if (method.accessFlags.isConstructor) {
                     constructors[methodTableEntry] = MethodWrapper.Encoded(method)
                 } else {
                     _virtualTable[methodTableEntry] = methodTableEntry
+                    methods[methodTableEntry] = MethodWrapper.Encoded(method)
                 }
             }
         }
@@ -65,6 +71,7 @@ class DexDefinedType(
                 if (_virtualTable.containsKey(methodID)) {
                     _interfaceTable[method.key] = methodID
                 } else {
+                    // TODO: Handle default methods
                     throw IllegalStateException(
                         "Required interface method ${method.key} not implemented in" +
                             " ${classDef.classDef.typeId.descriptor}"
diff --git a/src/main/kotlin/vm/classloader/MockedType.kt b/src/main/kotlin/vm/classloader/MockedType.kt
index a017a5f..340e045 100644
--- a/src/main/kotlin/vm/classloader/MockedType.kt
+++ b/src/main/kotlin/vm/classloader/MockedType.kt
@@ -1,6 +1,9 @@
 package com.yhs0602.vm.classloader
 
 import com.yhs0602.vm.MethodWrapper
+import com.yhs0602.vm.makeMockedConstructor
+import com.yhs0602.vm.makeMockedMethod
+import java.lang.reflect.Modifier
 
 class MockedType(
     override val clazz: Class<*>,
@@ -16,6 +19,7 @@ class MockedType(
     private val _virtualTable: MutableMap<MethodTableEntry, MethodTableEntry> = mutableMapOf()
     override val methods = mutableMapOf<MethodTableEntry, MethodWrapper>()
     override val constructors = mutableMapOf<MethodTableEntry, MethodWrapper>()
+    override val staticMethods = mutableMapOf<MethodTableEntry, MethodWrapper>()
 
     init {
         // populate v-table and i-table of the class
@@ -26,12 +30,19 @@ class MockedType(
         }
         // update the v-table with the current class's methods
         for (method in clazz.methods) {
-            val methodId = method.methodId()
-            val methodTableEntry = MethodTableEntry(
-                methodId.name,
-                methodId.protoId
-            )
-            _virtualTable[methodTableEntry] = methodTableEntry
+            val methodId = method.methodTableEntry()
+            // if this is not a static method
+            if (Modifier.isStatic(method.modifiers)) {
+                staticMethods[methodId] = MethodWrapper.Mocked(makeMockedMethod(clazz, method))
+            } else {
+                _virtualTable[methodId] = methodId
+                methods[methodId] = MethodWrapper.Mocked(makeMockedMethod(clazz, method))
+            }
+        }
+        // Update the constructors
+        for (constructor in clazz.constructors) {
+            val methodTableEntry = constructor.methodTableEntry()
+            constructors[methodTableEntry] = MethodWrapper.Mocked(makeMockedConstructor(clazz, constructor))
         }
         // update the i-table with the current class's interfaces
         for (interfaceTypeId in interfaces) {
@@ -41,7 +52,17 @@ class MockedType(
                 if (_virtualTable.containsKey(methodID)) {
                     _interfaceTable[method.key] = methodID
                 } else {
-                    throw IllegalStateException("Required interface method ${method.key} not implemented in ${clazz.name}")
+                    if (method.key.isDefault()) {
+                        _virtualTable[methodID] = methodID
+                        _interfaceTable[method.key] = methodID
+                    } else {
+                        throw IllegalStateException(
+                            "Required interface method ${method.key} not implemented in ${clazz.name}," +
+                                " required by ${interfaceTypeId.clazz.name}, ${method.key.method?.declaringClass?.isInterface}" +
+                                " ${!Modifier.isAbstract(method.key.method?.modifiers ?: 0)}" +
+                                " ${!Modifier.isStatic(method.key.method?.modifiers ?: 0)}"
+                        )
+                    }
                 }
             }
         }
diff --git a/src/main/kotlin/vm/classloader/ObjectType.kt b/src/main/kotlin/vm/classloader/ObjectType.kt
index 811374a..4d31700 100644
--- a/src/main/kotlin/vm/classloader/ObjectType.kt
+++ b/src/main/kotlin/vm/classloader/ObjectType.kt
@@ -3,6 +3,7 @@ package com.yhs0602.vm.classloader
 import com.yhs0602.vm.MethodWrapper
 import com.yhs0602.vm.makeMockedConstructor
 import com.yhs0602.vm.makeMockedMethod
+import java.lang.reflect.Modifier
 
 data object ObjectType : Type() {
     override fun isAssignableTo(other: Type): Boolean {
@@ -19,6 +20,7 @@ data object ObjectType : Type() {
     private val _virtualTable: MutableMap<MethodTableEntry, MethodTableEntry> = mutableMapOf()
     override val descriptor: String = "Ljava/lang/Object;"
     override val methods = mutableMapOf<MethodTableEntry, MethodWrapper>()
+    override val staticMethods = mutableMapOf<MethodTableEntry, MethodWrapper>()
     override val constructors = mutableMapOf<MethodTableEntry, MethodWrapper>()
     override val clazz: Class<*> = java.lang.Object::class.java
 
@@ -26,10 +28,16 @@ data object ObjectType : Type() {
         // populate v-table and i-table of Object
         for (method in java.lang.Object::class.java.methods) {
             val methodId = method.methodTableEntry()
-            _virtualTable[methodId] = methodId
-            methods[methodId] = MethodWrapper.Mocked(
-                makeMockedMethod(java.lang.Object::class.java, method)
-            )
+            if (Modifier.isStatic(method.modifiers)) {
+                staticMethods[methodId] = MethodWrapper.Mocked(
+                    makeMockedMethod(java.lang.Object::class.java, method)
+                )
+            } else {
+                _virtualTable[methodId] = methodId
+                methods[methodId] = MethodWrapper.Mocked(
+                    makeMockedMethod(java.lang.Object::class.java, method)
+                )
+            }
         }
         for (constructorMethod in java.lang.Object::class.java.constructors) {
             val methodId = constructorMethod.methodTableEntry()
diff --git a/src/main/kotlin/vm/classloader/PrimitiveType.kt b/src/main/kotlin/vm/classloader/PrimitiveType.kt
index 697ac82..413a9c0 100644
--- a/src/main/kotlin/vm/classloader/PrimitiveType.kt
+++ b/src/main/kotlin/vm/classloader/PrimitiveType.kt
@@ -14,9 +14,12 @@ class Primitive(override val descriptor: String) : Type() {
     override val interfaceTable: Map<MethodTableEntry, MethodTableEntry> = emptyMap()
 
     // no v table for primitive types
+    // TODO: java.lang.xxx.TYPE
     override val virtualTable: Map<MethodTableEntry, MethodTableEntry> = emptyMap()
     override val methods = emptyMap<MethodTableEntry, MethodWrapper>()
     override val constructors = emptyMap<MethodTableEntry, MethodWrapper>()
+    override val staticMethods = emptyMap<MethodTableEntry, MethodWrapper>()
+
     override val clazz: Class<*> by lazy {
         when (descriptor) {
             "Z" -> java.lang.Boolean.TYPE
diff --git a/src/main/kotlin/vm/classloader/Type.kt b/src/main/kotlin/vm/classloader/Type.kt
index 67192ae..7853157 100644
--- a/src/main/kotlin/vm/classloader/Type.kt
+++ b/src/main/kotlin/vm/classloader/Type.kt
@@ -2,11 +2,32 @@ package com.yhs0602.vm.classloader
 
 import com.yhs0602.dex.ProtoId
 import com.yhs0602.vm.MethodWrapper
+import java.lang.reflect.Method
+import java.lang.reflect.Modifier
 
 data class MethodTableEntry(
     val name: String,
-    val protoId: ProtoId
-)
+    val protoId: ProtoId,
+    val method: Method?
+) {
+    override fun equals(other: Any?): Boolean {
+        if (this === other) return true
+        if (javaClass != other?.javaClass) return false
+
+        other as MethodTableEntry
+
+        if (name != other.name) return false
+        if (protoId != other.protoId) return false
+
+        return true
+    }
+
+    override fun hashCode(): Int {
+        var result = name.hashCode()
+        result = 31 * result + protoId.hashCode()
+        return result
+    }
+}
 
 sealed class Type {
 
@@ -16,6 +37,7 @@ sealed class Type {
     abstract val virtualTable: Map<MethodTableEntry, MethodTableEntry>
     abstract val descriptor: String
     abstract val methods: Map<MethodTableEntry, MethodWrapper>
+    abstract val staticMethods: Map<MethodTableEntry, MethodWrapper>
     abstract val constructors: Map<MethodTableEntry, MethodWrapper>
     abstract val clazz: Class<*>
 
@@ -64,4 +86,10 @@ sealed class Type {
         return false
     }
 
+}
+
+fun MethodTableEntry.isDefault(): Boolean {
+    // Check if the method is a default method in the interface
+    if (method == null) return false
+    return method.declaringClass.isInterface && !Modifier.isAbstract(method.modifiers) && !Modifier.isStatic(method.modifiers)
 }
\ No newline at end of file
diff --git a/src/test/kotlin/AdvancedTest.kt b/src/test/kotlin/AdvancedTest.kt
index cc80ec3..bfd5a58 100644
--- a/src/test/kotlin/AdvancedTest.kt
+++ b/src/test/kotlin/AdvancedTest.kt
@@ -82,7 +82,10 @@ class AdvancedTest {
                 GeneralMockedClass(System::class.java),
                 GeneralMockedClass(Intrinsics::class.java),
                 GeneralMockedClass(Object::class.java),
-                GeneralMockedClass(PrintStream::class.java)
+                GeneralMockedClass(PrintStream::class.java),
+                GeneralMockedClass(kotlin.jvm.internal.Lambda::class.java),
+                GeneralMockedClass(kotlin.jvm.functions.Function0::class.java),
+                GeneralMockedClass(kotlin.jvm.functions.Function2::class.java),
             )
         )
     }
@@ -102,7 +105,8 @@ class AdvancedTest {
                 GeneralMockedClass(PrintStream::class.java),
                 GeneralMockedClass(Math::class.java),
                 GeneralMockedClass(File::class.java),
-                GeneralMockedClass(java.lang.Double::class.java)
+                GeneralMockedClass(java.lang.Double::class.java),
+                GeneralMockedClass(kotlin.jvm.internal.Lambda::class.java),
             )
         )
     }