Use custom logic for Rounding Down Operation

* add custom logic for truncating extra decimal digits

* improve CurrencyRounderTest with Parameterized Tests

* fix spotless errors

* clean up code

library/src/main/java/com/cottacush/android/currencyedittext/CurrencyInputWatcher.kt

@@ -19,13 +19,11 @@ import android.annotation.SuppressLint
 import android.text.Editable
 import android.text.TextWatcher
 import android.widget.EditText
-import java.lang.IllegalArgumentException
-import java.math.RoundingMode
 import java.text.DecimalFormat
 import java.text.DecimalFormatSymbols
 import java.text.NumberFormat
 import java.text.ParseException
-import java.util.Locale
+import java.util.*
 import kotlin.math.min
 
 class CurrencyInputWatcher(
@@ -49,12 +47,9 @@ class CurrencyInputWatcher(
     private val wholeNumberDecimalFormat =
         (NumberFormat.getNumberInstance(locale) as DecimalFormat).apply {
             applyPattern("#,##0")
-            roundingMode = RoundingMode.DOWN
         }
 
-    private val fractionDecimalFormat = (NumberFormat.getNumberInstance(locale) as DecimalFormat).apply {
-        roundingMode = RoundingMode.DOWN
-    }
+    private val fractionDecimalFormat = (NumberFormat.getNumberInstance(locale) as DecimalFormat)
 
     val decimalFormatSymbols: DecimalFormatSymbols
         get() = wholeNumberDecimalFormat.decimalFormatSymbols
@@ -100,6 +95,13 @@ class CurrencyInputWatcher(
             if (numberWithoutGroupingSeparator == decimalFormatSymbols.decimalSeparator.toString()) {
                 numberWithoutGroupingSeparator = "0$numberWithoutGroupingSeparator"
             }
+
+            numberWithoutGroupingSeparator = truncateNumberToMaxDecimalDigits(
+                numberWithoutGroupingSeparator,
+                maxNumberOfDecimalPlaces,
+                decimalFormatSymbols.decimalSeparator
+            )
+
             val parsedNumber = fractionDecimalFormat.parse(numberWithoutGroupingSeparator)!!
             val selectionStartIndex = editText.selectionStart
             if (hasDecimalPoint) {

library/src/main/java/com/cottacush/android/currencyedittext/CurrencyRounder.kt

@@ -0,0 +1,51 @@
+/**
+ * Copyright (c) 2019 Cotta & Cush Limited.
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *     http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+package com.cottacush.android.currencyedittext
+
+/**
+ * Helper method to truncate extra decimal digits from numbers.
+ * Was created because the previously used approach, [java.math.RoundingMode.DOWN] approach
+ * didn't work correctly for some devices.
+ *
+ * @param number the original number to format
+ * @param maxDecimalDigits the maximum number of decimal digits permitted
+ * @param decimalSeparator the decimal separator of the currently selected locale
+ * @return a version of number that has a maximum of [maxDecimalDigits] decimal digits.
+ * e.g.
+ * - 14.333 with 2 max decimal digits return 14.33
+ * - 19.2 with 2 max decimal digits return 19.2
+ */
+fun truncateNumberToMaxDecimalDigits(
+    number: String,
+    maxDecimalDigits: Int,
+    decimalSeparator: Char
+): String {
+    // Split number into whole and decimal part
+    val arr = number
+        .split(decimalSeparator)
+        .toMutableList()
+
+    // We should have exactly 2 elements in our string;
+    // the whole part and the decimal part
+    if (arr.size != 2) {
+        return number
+    }
+
+    // Take the first n (or shorter) from the decimal digits.
+    arr[1] = arr[1].take(maxDecimalDigits)
+
+    return arr.joinToString(separator = decimalSeparator.toString())
+}

library/src/test/java/com/cottacush/android/currencyedittext/CurrencyInputWatcherTest.kt

@@ -27,6 +27,7 @@ class CurrencyInputWatcherTest {
     // TODO Add more locale tests by their, tags, decimal separator and theur grouping separator
     private val locales = listOf(
             LocaleVars("en-NG", '.', ',', "$ "),
+            LocaleVars("en-US", '.', ',', "$ "),
             LocaleVars("da-DK", ',', '.', "$ "),
             LocaleVars("fr-CA", ',', ' ', "$ ")
     )
@@ -399,6 +400,23 @@ class CurrencyInputWatcherTest {
         }
     }
 
+    @Test
+    fun `Should retain valid number if imputed`() {
+        // This test tries to replicate issue #29 which fails on some devices and passes for some.
+        // It however passes on my local. but might be helpful to have the test in here.
+        for (locale in locales) {
+            val currentEditTextContent = "515${locale.decimalSeparator}809"
+            val expectedText = "${locale.currencySymbol}515${locale.decimalSeparator}809"
+
+            val (editText, editable, watcher) = setupTestVariables(locale, decimalPlaces = 3)
+            `when`(editable.toString()).thenReturn(currentEditTextContent)
+
+            watcher.runAllWatcherMethods(editable)
+
+            verify(editText, times(1)).setText(expectedText)
+        }
+    }
+
     private fun setupTestVariables(locale: LocaleVars, decimalPlaces: Int = 2): TestVars {
         val editText = mock(CurrencyEditText::class.java)
         val editable = mock(Editable::class.java)

library/src/test/java/com/cottacush/android/currencyedittext/CurrencyRounderTest.kt

@@ -0,0 +1,81 @@
+/**
+ * Copyright (c) 2019 Cotta & Cush Limited.
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *     http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+package com.cottacush.android.currencyedittext
+
+import org.junit.Assert
+import org.junit.Test
+import org.junit.runner.RunWith
+import org.junit.runners.Parameterized
+
+@RunWith(Parameterized::class)
+class CurrencyRounderTest(
+    private val current: String,
+    private val expected: String,
+    private val decimalDigits: Int,
+    private val decimalSeparator: Char
+) {
+
+    companion object {
+        private const val POINT_DECIMAL_SEPARATOR = '.'
+        private const val COMMA_DECIMAL_SEPARATOR = ','
+        private const val TWO = 2
+        private const val THREE = 3
+
+        private val emptyStringTestCase = arrayOf("", "", TWO, POINT_DECIMAL_SEPARATOR)
+        private val extraDecimalTestCase1 = arrayOf("223.55644234234", "223.55", TWO, POINT_DECIMAL_SEPARATOR)
+        private val extraDecimalTestCaseThreeDpVersion = arrayOf("223.55644234234", "223.556", THREE, POINT_DECIMAL_SEPARATOR)
+        private val extraDecimalTestCase2 = arrayOf("334,242,203.4234234", "334,242,203.423", THREE, POINT_DECIMAL_SEPARATOR)
+        private val extraDecimalTestCaseWhiteSpaceGrouping = arrayOf("334 242 203.4234234", "334 242 203.423", THREE, POINT_DECIMAL_SEPARATOR)
+        private val extraDecimalTestCaseCommaDecimal = arrayOf("334.242.203,4234234", "334.242.203,42", TWO, COMMA_DECIMAL_SEPARATOR)
+        private val emptyWholeTestCase = arrayOf(".4234234", ".42", TWO, POINT_DECIMAL_SEPARATOR)
+        private val emptyDecimalTestCase = arrayOf("4,234,234.", "4,234,234.", TWO, POINT_DECIMAL_SEPARATOR)
+        private val shorterDecimalTestCase = arrayOf("23.45", "23.45", THREE, POINT_DECIMAL_SEPARATOR)
+        private val shorterDecimalTestCase2 = arrayOf("23.4", "23.4", THREE, POINT_DECIMAL_SEPARATOR)
+        private val exactDecimalTestCase = arrayOf("515.809", "515.809", THREE, POINT_DECIMAL_SEPARATOR)
+        private val noDecimalTestCase = arrayOf("5 809", "5 809", THREE, POINT_DECIMAL_SEPARATOR)
+        private val noDecimalTestCase2 = arrayOf("5", "5", THREE, POINT_DECIMAL_SEPARATOR)
+        private val noDecimalTestCase3 = arrayOf("5,452,635,242,242,423,434,333", "5,452,635,242,242,423,434,333", THREE, POINT_DECIMAL_SEPARATOR)
+        private val multipleDecimalTestCase = arrayOf("343,432,242,342", "343,432,242,342", TWO, COMMA_DECIMAL_SEPARATOR)
+
+        @JvmStatic
+        @Parameterized.Parameters
+        fun data(): Iterable<Array<Any>> = listOf(
+            emptyStringTestCase,
+            extraDecimalTestCase1,
+            extraDecimalTestCaseThreeDpVersion,
+            extraDecimalTestCase2,
+            extraDecimalTestCaseWhiteSpaceGrouping,
+            extraDecimalTestCaseCommaDecimal,
+            emptyWholeTestCase,
+            emptyDecimalTestCase,
+            shorterDecimalTestCase,
+            shorterDecimalTestCase2,
+            exactDecimalTestCase,
+            noDecimalTestCase,
+            noDecimalTestCase2,
+            noDecimalTestCase3,
+            multipleDecimalTestCase
+        )
+    }
+
+    @Test
+    fun `should return expected value for set of valid inputs`() {
+        Assert.assertEquals(
+            expected,
+            truncateNumberToMaxDecimalDigits(current, decimalDigits, decimalSeparator)
+        )
+    }
+}

sample/src/main/res/layout/activity_main.xml

@@ -11,7 +11,7 @@
             app:currencySymbol="$"
             app:useCurrencySymbolAsHint="true"
             app:localeTag="en-NG"
-            app:maxNumberOfDecimalDigits="2"
+            app:maxNumberOfDecimalDigits="3"
             android:layout_width="wrap_content"
             android:layout_height="60dp"
             android:ems="10"