Challenge Submittal

Decoder.java

@@ -0,0 +1,97 @@
+import java.io.BufferedReader;
+import java.io.IOException;
+import java.io.InputStreamReader;
+
+public class Decoder {
+
+  StringBuilder preamble = new StringBuilder();
+  StringBuilder response = new StringBuilder();
+
+  public Decoder() {
+    run();
+  }
+
+  public void run() {
+    BufferedReader reader = new BufferedReader(new InputStreamReader(System.in));
+    boolean preambleFound = false;
+
+    int bit = 0;
+
+
+    while (bit > -1) {
+      try {
+        //Read one character at a time
+        bit = reader.read();
+        char bitChar = (char) bit;
+
+        // Check if bit is a 0 or 1
+        if (bit == 49 || bit == 48) {
+
+          //If the preamble has not been found we need to keep looking for it
+          if (!preambleFound) {
+
+            //if the preamble stringbuilder queue is at 88 then check if it equals CAPTIVATION
+            if (preamble.length() >= 88) {
+
+              // Does preamble = CAPTIVATION?
+              String decodedPreamble = decodeBinaryString(preamble.toString());
+              if (decodedPreamble.compareTo("CAPTIVATION") == 0) {
+                //the preamble was found. set a flag and reset the preamble stringbuilder queue
+                preambleFound = true;
+                preamble = new StringBuilder();
+
+                //Add current bit we just received to response string
+                response.append(bitChar);
+              } else {
+                //preamble not found, dequeue character from stringbuilder
+                preamble.deleteCharAt(0);
+                //append new character to end of string builder.
+                preamble.append(bitChar);
+              }
+
+            } else {
+              //preamble stringbuilder isnt long enough to be the preamble yet, so simply append to it.
+              preamble.append(bitChar);
+            }
+
+          } else {
+            // Preamble was found now accumulate next 100 characters and then print to screen.
+            if (response.length() < 800) {
+              // keep adding to response string
+              response.append(bitChar);
+            } else {
+              // We have 100 characters, print to screen
+              System.out.println(decodeBinaryString(response.toString()));
+
+              // reset response string holder
+              response = new StringBuilder();
+              // reset preambleFound Flag
+              preambleFound = false;
+
+            }
+          }
+        }
+      } catch (IOException e) {
+        e.printStackTrace();
+      }
+
+    }
+  }
+
+  //Converts a string of 1's and 0's to a character string
+  public String decodeBinaryString(String binaryString) {
+    int intChar;
+    String stringChar;
+    StringBuilder stringBuilder = new StringBuilder();
+    for (int i = 0; i < binaryString.length(); i += 8) {
+      intChar = Integer.parseInt(binaryString.substring(i, i + 8), 2);
+      stringChar = Character.toString((char) intChar);
+      stringBuilder.append(stringChar);
+    }
+    return stringBuilder.toString();
+  }
+
+  public static void main(String arg[]) {
+    new Decoder();
+  }
+}

README.md

@@ -20,3 +20,8 @@ Develop an application that:
 - Your solution will be judged for correctness, performance, and style
 - You may use any language you'd like, but you can only use standard libraries
 - Your solution must be your own original work
+
+## Build & Run Instructions
+- Ensure the openJDK 8 is installed
+- In the directory where the Decoder.java file is, run "javac Decoder.java" in a terminal to compile the class
+- In the same directory run "java Decoder" to execute the app.