diff --git a/exceptions/ElementNotFound.go b/exceptions/ElementNotFound.go
index 1baee3c..5ca9800 100644
--- a/exceptions/ElementNotFound.go
+++ b/exceptions/ElementNotFound.go
@@ -4,7 +4,7 @@ type ElementNotFoundException struct {
 	RuntimeException
 }
 
-func NewElementNotFoundException(message string, getStackTrace bool) *ElementNotFoundException {
+func NewElementNotFoundException(message interface{}, getStackTrace bool) *ElementNotFoundException {
 	return &ElementNotFoundException{
 		NewRuntimeException(
 			message,
diff --git a/exceptions/IndexOutOfBoundError.go b/exceptions/IndexOutOfBoundError.go
index 158ac37..d123887 100644
--- a/exceptions/IndexOutOfBoundError.go
+++ b/exceptions/IndexOutOfBoundError.go
@@ -4,7 +4,7 @@ type IndexOutOfBound struct {
 	RuntimeException
 }
 
-func NewIndexOutOfBound(message string, getStackTrace bool) IndexOutOfBound {
+func NewIndexOutOfBound(message interface{}, getStackTrace bool) IndexOutOfBound {
 	return IndexOutOfBound{
 		NewRuntimeException(
 			message,
diff --git a/exceptions/NPE.go b/exceptions/NPE.go
index fb4dfa2..ac1ed35 100644
--- a/exceptions/NPE.go
+++ b/exceptions/NPE.go
@@ -4,7 +4,7 @@ type NPE struct {
 	RuntimeException
 }
 
-func NewNPE(message string, getStackTrace bool) *NPE {
+func NewNPE(message interface{}, getStackTrace bool) *NPE {
 	return &NPE{
 		NewRuntimeException(
 			message,
diff --git a/exceptions/OperationNotSupportedException.go b/exceptions/OperationNotSupportedException.go
index 688c51b..634183a 100644
--- a/exceptions/OperationNotSupportedException.go
+++ b/exceptions/OperationNotSupportedException.go
@@ -4,7 +4,7 @@ type OperationNotSupportedException struct {
 	RuntimeException
 }
 
-func NewOperationNotSupportedException(message string, getStackTrace bool) OperationNotSupportedException {
+func NewOperationNotSupportedException(message interface{}, getStackTrace bool) OperationNotSupportedException {
 	return OperationNotSupportedException{
 		NewRuntimeException(
 			message,
diff --git a/exceptions/RuntimeException.go b/exceptions/RuntimeException.go
index 6bebe0d..73762f1 100644
--- a/exceptions/RuntimeException.go
+++ b/exceptions/RuntimeException.go
@@ -1,6 +1,7 @@
 package exceptions
 
 import (
+	"fmt"
 	"io"
 	"os"
 	"strings"
@@ -13,7 +14,7 @@ type RuntimeException struct {
 	cause            Exception
 }
 
-func NewRuntimeException(message, exceptionMessage string, getStackTrace bool, cause interface{}) RuntimeException {
+func NewRuntimeException(message interface{}, exceptionMessage string, getStackTrace bool, cause interface{}) RuntimeException {
 	var stackTrace []StackTrace = nil
 	if getStackTrace {
 		stackTrace = GetStackTrace()
@@ -24,13 +25,20 @@ func NewRuntimeException(message, exceptionMessage string, getStackTrace bool, c
 	}
 
 	var causeException Exception = nil
-	switch cause.(type) {
-	case Exception:
-		causeException = cause.(Exception)
+	if cause != nil {
+		switch cause.(type) {
+		case Exception:
+			causeException = cause.(Exception)
+		default:
+			causeException = RuntimeException{
+				message:          fmt.Sprint(cause),
+				exceptionMessage: "exception caused:",
+			}
+		}
 	}
 
 	return RuntimeException{
-		message:          message,
+		message:          fmt.Sprint(message),
 		exceptionMessage: exceptionMessage,
 		stackTrace:       stackTrace,
 		cause:            causeException,
diff --git a/main.go b/main.go
index 991dbcb..386f81f 100644
--- a/main.go
+++ b/main.go
@@ -13,12 +13,11 @@ func main() {
 		fmt.Println("recover from panic", r)
 		return nil, exceptions.NewIndexOutOfBound(fmt.Sprint(r), true)
 	})
-	exception := err.(exceptions.Exception)
 	exceptions.NewRuntimeException(
-		exception.Error(),
+		err,
 		"test exception:",
 		true,
-		exception,
+		err,
 	).PrintStackTrace()
 
 	list := collections.NewArrayList()