valid FCS output

Zadanie-03/src/com/tylkowski/crc/CrcTask.java

@@ -1,7 +1,5 @@
 package com.tylkowski.crc;
 
-import java.lang.reflect.Field;
-import java.nio.charset.Charset;
 import java.util.Arrays;
 
 class CrcTask {
@@ -10,19 +8,12 @@ class CrcTask {
     private short[] polyGenerator;
     private String rawMessage;
 
-    CrcTask(String message, String rawMessage) throws NoSuchFieldException, IllegalAccessException {
+    CrcTask(String message) {
-        setEncoding();
+        this.rawMessage = message;
         this.message = formatMessage(toBinaryString(message)) + "0000000000000000";
-        this.rawMessage = rawMessage;
         createGeneratingPolynomial();
     }
 
-    private void setEncoding() throws NoSuchFieldException, IllegalAccessException {
-        System.setProperty("file.encoding", "ISO-8859-1");
-        Field charset = Charset.class.getDeclaredField("defaultCharset");
-        charset.setAccessible(true);
-        charset.set(null, null);
-    }
 
     private String formatMessage(String message) {
         int firstNonZeroVal = 0;
@@ -59,7 +50,7 @@ class CrcTask {
                 short[] piece = Arrays.copyOfRange(messageAsShortArray, 0, Math.min(polyGenerator.length, messageAsShortArray.length));
                 if (piece.length < polyGenerator.length) {
                     fillPolynomial(piece);
-                    return "" + getCharFromShortArray(piece, 0, 8) + getCharFromShortArray(piece, piece.length - 8, piece.length);
+                    return createTwoCharsOfFCS(piece);
                 }
                 short[] remainder = calcXOR(piece, polyGenerator);
                 remainder = removeUnecessaryZeros(remainder);
@@ -69,6 +60,17 @@ class CrcTask {
 
     }
 
+    private String createTwoCharsOfFCS(short[] piece) {
+        short[] firstPiece = Arrays.copyOfRange(piece, 0, 8);
+        short[] secondPiece = Arrays.copyOfRange(piece, piece.length - 8, piece.length);
+        short[] mergedPieces = new short[firstPiece.length + secondPiece.length];
+        for (int i = 0; i < firstPiece.length; i++) {
+            mergedPieces[i] = firstPiece[i];
+            mergedPieces[i + 8] = secondPiece[i];
+        }
+        return "0x" + Integer.toHexString(Integer.parseInt(shortArrayToBinaryString(mergedPieces), 2));
+    }
+
     private short[] createMessageFromRemainderAndPartFromOldMessage(short[] remainder, short[] msg) {
         short[] tempArr = new short[remainder.length + msg.length - polyGenerator.length];
         System.arraycopy(remainder, 0, tempArr, 0, remainder.length);
@@ -106,12 +108,6 @@ class CrcTask {
         return binaryString.toString();
     }
 
-    private char getCharFromShortArray(short[] piece, int from, int to) {
-        short[] sign = Arrays.copyOfRange(piece, from, to);
-        int character = Integer.parseInt(shortArrayToBinaryString(sign), 2);
-        return (char) character;
-    }
-
     private void fillPolynomial(short[] piece) {
         while (piece.length % 8 != 0) {
             piece = addZeroAtBeginningOfArray(piece);
@@ -171,7 +167,10 @@ class CrcTask {
     }
 
     boolean decode(String encodedString) {
+        String fcs = encodedString.substring(encodedString.indexOf("0x"), encodedString.length());
+        encodedString = encodedString.replace(fcs, "");
         encodedString = toBinaryString(encodedString);
+        encodedString = encodedString + toBinaryStringFromHexValue(fcs);
         encodedString = fillPoly(encodedString);
         short[] encodedShortArray = convertBinaryStringToShortArray(encodedString);
         encodedShortArray = swapPolynomialValues(encodedShortArray);
@@ -194,6 +193,11 @@ class CrcTask {
         }
     }
 
+    private String toBinaryStringFromHexValue(String hexString) {
+        hexString = hexString.substring(2, hexString.length());
+        return String.valueOf(Integer.toBinaryString(Integer.parseInt(hexString, 16)));
+    }
+
     private String toBinaryString(String encodedString) {
         StringBuilder stringBuilder = new StringBuilder();
         for (int i = 0; i < encodedString.length(); i++) {

Zadanie-03/src/com/tylkowski/crc/Main.java

@@ -2,12 +2,12 @@ package com.tylkowski.crc;
 
 public class Main {
 
-    public static void main(String[] args) throws NoSuchFieldException, IllegalAccessException {
+    public static void main(String[] args) {
         // in command line type "1" for mode and "b" for message
         // example "1" "b" -> this will encode string "b" and return FCS
-        // example "2" "bXY" -> this will decode string "bXY" and return true if it is valid or false if not
+        // example "2" "bX" -> this will decode string "bX" and return true if it is valid or false if not
-        // X and Y - 1 and 2 character of FCS
+		// X - FCS
-        CrcTask crcTask = new CrcTask(args[1], args[1]);
+        CrcTask crcTask = new CrcTask(args[1]);
         if (args[0].equals("1")) {
             //create FCS
             System.out.println(crcTask.encode());