diff --git a/src/main/kotlin/com/cubetiqs/libra/moneyutils/MoneyConfig.kt b/src/main/kotlin/com/cubetiqs/libra/moneyutils/MoneyConfig.kt
index e58792e..c41a90b 100644
--- a/src/main/kotlin/com/cubetiqs/libra/moneyutils/MoneyConfig.kt
+++ b/src/main/kotlin/com/cubetiqs/libra/moneyutils/MoneyConfig.kt
@@ -11,43 +11,45 @@ object MoneyConfig {
     private const val SPLIT_ORD_2 = '='
 
     /**
+     * All money currencies and its rate are stored in memory state for exchange or compute the value.
+     *
      * Key is the currency
      * Value is the rate
      */
-    private val config = mutableMapOf<String, Double>()
+    private val config: MutableMap<String, Double> = mutableMapOf()
 
-    fun parse(config: String): Map<String, Double> {
-        val result = mutableMapOf<String, Double>()
+    /**
+     * Parse the config string to currency's map within rates
+     * Key is money's currency (String)
+     * Value is money's value (Double)
+     */
+    fun parse(config: String, clearAllStates: Boolean = true) {
+        if (clearAllStates) {
+            this.config.clear()
+        }
         val rates = config.split(SPLIT_ORD_1)
-        /**
-         * USD=1
-         * KHR=4000
-         * EUR=0.99
-         *
-         * USD -> currency
-         * 1 -> value
-         */
         rates.map { i ->
             val temp = i.split(SPLIT_ORD_2)
             if (temp.size == 2) {
-                val currency = temp[0]
+                val currency = temp[0].toUpperCase()
                 val value = temp[1].toDouble()
-                result.put(currency.toUpperCase(), value)
+                if (this.config.containsKey(currency)) {
+                    this.config.replace(currency, value)
+                } else {
+                    this.config.put(currency, value)
+                }
             } else {
-                throw IllegalArgumentException("invalid value!")
+                throw MoneyCurrencyStateException("money config format is not valid!")
             }
         }
-
-        // if you want to use all set currencies without remove from memory, we should remove this line
-        this.config.clear()
-        this.config.putAll(result)
-        return result
     }
 
     // all currencies with its rate
     fun getConfig() = this.config
 
+    @Throws(MoneyCurrencyStateException::class)
     fun getRate(currency: String): Double {
-        return getConfig()[currency.toUpperCase()] ?: throw IllegalArgumentException("currency not found")
+        return getConfig()[currency.toUpperCase()]
+            ?: throw MoneyCurrencyStateException("money currency $currency is not valid!")
     }
 }
\ No newline at end of file
diff --git a/src/main/kotlin/com/cubetiqs/libra/moneyutils/MoneyCurrencyStateException.kt b/src/main/kotlin/com/cubetiqs/libra/moneyutils/MoneyCurrencyStateException.kt
new file mode 100644
index 0000000..493cb0b
--- /dev/null
+++ b/src/main/kotlin/com/cubetiqs/libra/moneyutils/MoneyCurrencyStateException.kt
@@ -0,0 +1,3 @@
+package com.cubetiqs.libra.moneyutils
+
+class MoneyCurrencyStateException(message: String? = null) : IllegalStateException(message ?: "money currency not found!")
\ No newline at end of file