From 6b7eab109596c8918f7bdab148fbcb33d4943b7b Mon Sep 17 00:00:00 2001
From: Timmy <timmy@automodules.com>
Date: Fri, 17 Apr 2026 13:10:27 +0800
Subject: [PATCH] =?UTF-8?q?=E4=BF=AE=E6=AD=A3=20Kotlin=20=E5=9B=9B?=
 =?UTF-8?q?=E6=8D=A8=E4=BA=94=E5=85=A5=EF=BC=88=E5=8E=9F=E6=9C=AC=20kotlin?=
 =?UTF-8?q?.math.round=20=E6=98=AF=E9=8A=80=E8=A1=8C=E5=AE=B6=E6=8D=A8?=
 =?UTF-8?q?=E5=85=A5=EF=BC=8C=E6=94=B9=E7=94=A8=20BigDecimal=20HALF=5FUP?=
 =?UTF-8?q?=EF=BC=89?=
MIME-Version: 1.0
Content-Type: text/plain; charset=UTF-8
Content-Transfer-Encoding: 8bit

---
 .../main/java/tw/local/botrates/MainActivity.kt    | 14 +++++++++-----
 1 file changed, 9 insertions(+), 5 deletions(-)

diff --git a/android/app/src/main/java/tw/local/botrates/MainActivity.kt b/android/app/src/main/java/tw/local/botrates/MainActivity.kt
index 5b4aed1..431fd8f 100644
--- a/android/app/src/main/java/tw/local/botrates/MainActivity.kt
+++ b/android/app/src/main/java/tw/local/botrates/MainActivity.kt
@@ -47,8 +47,11 @@ import androidx.compose.ui.unit.sp
 import kotlinx.coroutines.Dispatchers
 import kotlinx.coroutines.launch
 import kotlinx.coroutines.withContext
+import java.math.BigDecimal
+import java.math.RoundingMode
 import java.net.HttpURLConnection
 import java.net.URL
+import java.text.DecimalFormat
 import java.text.SimpleDateFormat
 import java.util.Date
 import java.util.Locale
@@ -82,13 +85,14 @@ private fun fetchRates(): List<Rate> {
 private fun parseAmount(s: String): Double? =
     s.filter { it != ',' && !it.isWhitespace() }.takeIf { it.isNotEmpty() }?.toDoubleOrNull()
 
-private fun formatTwd(v: Double): String {
-    val rounded = kotlin.math.round(v * 100.0) / 100.0
-    return "%,.2f".format(rounded)
-}
+private fun roundHalfUp(v: Double): BigDecimal =
+    BigDecimal.valueOf(v).setScale(2, RoundingMode.HALF_UP)
+
+private fun formatTwd(v: Double): String =
+    DecimalFormat("#,##0.00").format(roundHalfUp(v))
 
 private fun formatTwdRaw(v: Double): String =
-    "%.2f".format(kotlin.math.round(v * 100.0) / 100.0)
+    roundHalfUp(v).toPlainString()
 
 class MainActivity : ComponentActivity() {
     override fun onCreate(savedInstanceState: Bundle?) {