Modified AssetAmount#multiply() and AssetAmount#divide() to not cast its value to a long primitive and thus preventing some overflow scenarios that the idea of using the UnsignedLong class is suposed to prevent

graphenej/src/main/java/cy/agorise/graphenej/AssetAmount.java

@@ -17,6 +17,7 @@ import java.io.DataOutput;
 import java.io.DataOutputStream;
 import java.io.IOException;
 import java.lang.reflect.Type;
+import java.math.BigDecimal;
 import java.math.RoundingMode;
 
 import cy.agorise.graphenej.errors.IncompatibleOperation;
@@ -91,7 +92,9 @@ public class AssetAmount implements ByteSerializable, JsonSerializable {
      * @return The same AssetAmount instance, but with the changed amount value.
      */
     public AssetAmount multiplyBy(double factor, RoundingMode roundingMode){
-        this.amount = UnsignedLong.valueOf(DoubleMath.roundToLong(this.amount.longValue() * factor, roundingMode));
+        BigDecimal originalAmount = new BigDecimal(amount.bigIntegerValue());
+        BigDecimal decimalResult = originalAmount.multiply(new BigDecimal(factor));
+        this.amount = UnsignedLong.valueOf(DoubleMath.roundToBigInteger(decimalResult.doubleValue(), roundingMode));
         return this;
     }
 
@@ -111,7 +114,9 @@ public class AssetAmount implements ByteSerializable, JsonSerializable {
      * @return: The same AssetAMount instance, but with the divided amount value
      */
     public AssetAmount dividedBy(double divisor, RoundingMode roundingMode){
-        this.amount = UnsignedLong.valueOf(DoubleMath.roundToLong(this.amount.longValue() / divisor, roundingMode));
+        BigDecimal originalAmount = new BigDecimal(amount.bigIntegerValue());
+        BigDecimal decimalAmount = originalAmount.divide(new BigDecimal(divisor), 18, RoundingMode.HALF_UP);
+        this.amount = UnsignedLong.valueOf(DoubleMath.roundToBigInteger(decimalAmount.doubleValue(), roundingMode));
         return this;
     }
 

graphenej/src/test/java/cy/agorise/graphenej/AssetAmountTest.java

@@ -1,13 +1,14 @@
 package cy.agorise.graphenej;
 
 import com.google.common.primitives.UnsignedLong;
+
 import org.junit.Before;
 import org.junit.Test;
 
-import static org.junit.Assert.*;
+import static org.junit.Assert.assertEquals;
 
 /**
- * Created by nelson on 2/23/17.
+ * Testing AssetAmount operations.
  */
 public class AssetAmountTest {
     private final int LARGE_VALUE = 1000;
@@ -27,4 +28,28 @@ public class AssetAmountTest {
         assertEquals(large.subtract(small).getAmount(), new AssetAmount(UnsignedLong.valueOf(LARGE_VALUE - SMALL_VALUE), testAsset).getAmount());
         assertEquals(small.subtract(large).getAmount(), new AssetAmount(UnsignedLong.valueOf(Math.abs(SMALL_VALUE - LARGE_VALUE)), testAsset).getAmount());
     }
+
+    @Test
+    public void testMultiplication(){
+        // Testing a simple multiplication by a double
+        AssetAmount result = large.multiplyBy(0.5);
+        assertEquals(500, result.getAmount().longValue());
+
+        // Testing the multiplication of a number that would normally give an overflow
+        AssetAmount max = new AssetAmount(UnsignedLong.valueOf(Long.MAX_VALUE), testAsset);
+        AssetAmount overMaxLong = max.multiplyBy(1.5);
+        assertEquals("13835058055282163712", overMaxLong.getAmount().toString(10));
+    }
+
+    @Test
+    public void testDivision(){
+        // Testing a simple division by a double
+        AssetAmount result = large.dividedBy(0.5);
+        assertEquals(2000, result.getAmount().longValue());
+
+        // Testing a division of a number that would normally give an overflow
+        AssetAmount max = new AssetAmount(UnsignedLong.valueOf(Long.MAX_VALUE), testAsset);
+        AssetAmount overMaxLong = max.dividedBy(0.8);
+        assertEquals("11529215046068469760", overMaxLong.getAmount().toString());
+    }
 }