Reduce memory alloc in read thread

Author: bastengao

android/src/main/java/com/bastengao/serialport/SerialPortApiModule.java

@@ -152,9 +152,9 @@ public static byte[] hexStringToByteArray(String s) {
 
     private static final char[] HEX_ARRAY = "0123456789ABCDEF".toCharArray();
 
-    public static String bytesToHex(byte[] bytes) {
-        char[] hexChars = new char[bytes.length * 2];
-        for (int j = 0; j < bytes.length; j++) {
+    public static String bytesToHex(byte[] bytes, int length) {
+        char[] hexChars = new char[length * 2];
+        for (int j = 0; j < length; j++) {
             int v = bytes[j] & 0xFF;
             hexChars[j * 2] = HEX_ARRAY[v >>> 4];
             hexChars[j * 2 + 1] = HEX_ARRAY[v & 0x0F];

android/src/main/java/com/bastengao/serialport/SerialPortWrapper.java

@@ -37,16 +37,15 @@ public SerialPortWrapper(String path, SerialPort serialPort, final EventSender s
         this.readThread = new Thread(new Runnable() {
             @Override
             public void run() {
+                byte[] buffer = new byte[64];
                 while (!closed.get()) {
                     try {
                         int size;
-                        byte[] buffer = new byte[64];
                         if (in == null) return;
                         size = in.read(buffer);
                         if (size > 0) {
                             WritableMap event = Arguments.createMap();
-                            byte[] data = Arrays.copyOf(buffer, size);
-                            String hex = SerialPortApiModule.bytesToHex(data);
+                            String hex = SerialPortApiModule.bytesToHex(buffer, size);
                             event.putString("data", hex);
                             event.putString("path", path);
                             sender.sendEvent(DataReceivedEvent, event);

package-lock.json

@@ -1,7 +1,7 @@
 {
   "name": "react-native-serial-port-api",
   "title": "React Native Serial Port API",
-  "version": "1.4.0-rc.2",
+  "version": "1.4.0-rc.3",
   "description": "React Native Serial Port API",
   "main": "lib/commonjs/index.js",
   "react-native": "src/index.ts",