Solution for 2016 AP Computer Science Free Response LogMessage - https://compsci.rocks/logmessage-solution/

constructor.java

public LogMessage( String message ) {
    int pos = message.indexOf(":");
    machineId = message.substring(0, pos);
    description = message.substring(pos + 1);
}

constructor_split.java

public LogMessage( String message ) {
  String[] spl = message.split(":");
  machineId = spl[0];
  description = spl[1];
}

containsKeyword.java

public boolean containsWord( String keyword ) { 
    if (keyword.equals(description))
        return true;
    else if (description.indexOf(keyword + " ") == 0) 
        return true; 
    else if (description.indexOf(" " + keyword + " ") >= 0) 
        return true; 
    else if (description.length() > keyword.length()
        && description.indexOf(" " + keyword) == description.length() - keyword.length() - 1) 
        return true; 
    return false; 
}

containsKeyword_regex.java

public boolean containsWord( String keyword ) { 
    return description.matches(".*(\\s|^)" + keyword + "(\\s|$).*");
}

containsWord_spaces.java

public boolean containsWord( String keyword ) { 
    return (" " + description + " ").indexOf(" " + keyword + " ") >= 0;
}

removeMessages.java

public List<LogMessage> removeMessages( String keyword ) {
    List<LogMessage> out = new ArrayList<>();
    for (int i=messageList.size() - 1; i>=0; i--) {
        if (messageList.get(i).containsWord(keyword)) {
            out.add(0, messageList.remove(i)); 
        }
    }
    return out; 
}