Week 9

Basic I/O; methods (functions); variable scope; strings.

Strings

We’ll see examples of a few mini-languages used within Java (and many other programming languages) when dealing with Strings.

First example: 

        public static void main(String[] args) {
            // Read a string and do the following:
            // 1. Print the original string.
            // 2. Print the string's length.
            // 3. Print the string in lower case.
            // 4. Print the string in upper case.
            // 5. Print the string with the first letter capitalized.
            // 6. Print the number of 'a's in the string.
            // 7. Print the string with all 'a's replaced by 'b's.
            // 8. Print the string with all consecutive 'a's replaced by a single 'a'.
            Scanner scan = new Scanner(System.in);
            String s = scan.nextLine();

            System.out.format("1. %s\n", s);
            System.out.format("2. %s\n", s.length());
            System.out.format("3. %s\n", s.toLowerCase());
            System.out.format("4. %s\n", s.toUpperCase());

            String firstLetter = s.substring(0, 1);
            String rest = s.substring(1);
            System.out.format("5. %s\n", firstLetter.toUpperCase() + rest);

            int acount = 0;
            for (int i = 0; i < s.length(); i = i + 1) {
                char c = s.charAt(i);
                if (c == 'a')
                    acount = acount + 1;
            }
            System.out.format("6. %s\n", acount);

            String r = s.replace("a", "b");
            System.out.format("7. %s\n", r);

            String r2 = s.replaceAll("a+", "a");
            System.out.format("8. %s\n", r2);
        }

Processing input

Reading

Java for Everyone, chapters 4-5. Chapter 4 is more review of concepts we covered when using Processing.

Homework