DAY 1

1) 

      import java.io.File;
      import java.util.Scanner;

      public class CharacterAnalysis {
          public static void main(String[] args) throws Exception {

              Scanner input = new Scanner(new File("character_data.txt"));

              int uppercase = 0;
              int lowercase = 0;
              int digits = 0;
              int whitespace = 0;
              int other = 0;

              while (input.hasNext()) {
                  String line = input.nextLine();

                  for (int i = 0; i < line.length(); i++) {
                      char ch = line.charAt(i);

                      if (Character.isUpperCase(ch)) {
                          uppercase++;
                      }
                      else if (Character.isLowerCase(ch)) {
                          lowercase++;
                      }
                      else if (Character.isDigit(ch)) {
                          digits++;
                      }
                      else if (Character.isWhitespace(ch)) {
                          whitespace++;
                      }
                      else {
                          other++;
                      }
                  }

                  // Account for the newline between lines.
                  whitespace++;
              }

              input.close();

              System.out.println("Character Analysis");
              System.out.println("------------------");
              System.out.println("Uppercase letters: " + uppercase);
              System.out.println("Lowercase letters: " + lowercase);
              System.out.println("Digits: " + digits);
              System.out.println("Whitespace: " + whitespace);
              System.out.println("Other characters: " + other);
          }
      }

2) 

    import java.util.Scanner;
    public class Initials {
        public static void main(String [] args) {
            Scanner sc = new Scanner(System.in);
            System.out.print("Enter your name: ");
            String first = sc.next();
            String last = sc.next();
            String initials = first.charAt(0)+"."+last.charAt(0)+".";
            System.out.println("Initials: " + initials);
        }
    }

OR (using one String variable and indexOf method)

    import java.util.Scanner;
    
    public class Initials {
        public static void main(String[] args) {
            Scanner sc = new Scanner(System.in);
    
            System.out.print("Enter your name: ");
            String name = sc.nextLine();
    
            int space = name.indexOf(' ');
    
            String initials = name.charAt(0) + "." +
                              name.charAt(space + 1) + ".";
    
            System.out.println("Initials: " + initials);
        }
    }

OR (using split method)

      import java.util.Scanner;

      public class Initials {
          public static void main(String[] args) {
              Scanner input = new Scanner(System.in);

              System.out.print("Enter name: ");
              String name = input.nextLine();

              String[] parts = name.split(" ");

              char firstInitial = parts[0].charAt(0);
              char lastInitial = parts[1].charAt(0);

              System.out.println("Initials: " + firstInitial + "." +
                                 lastInitial + ".");
          }
      }

3)

1. Answer: 32
2. Answer: e
3. Answer: hannah.charAt(15)

4) 

    public class Decode {
        public static void main(String [] args) {
            String s = "Iqqf\"Lqd#\"[qw\"hkiwtgf\"kv\"qwv#";
            String message="";
            for(int i = 0; i < s.length(); i++) {
                char c = s.charAt(i); //get current char
                c -= 2; //shift down by 2
                message += c; //append to String
            }
            System.out.println(message); //Good Job! You figured it out!
        }
    }

5)

a. Answer: AB-1X
b. Answer: Denver
c. Answer: false

6)

    int count = 0;
    if(Character.isUpperCase(sentence.charAt(0))) { //if the first letter is upper case
       count++;//count it!
    }
    
    int space = sentence.indexOf(" ");//finds the index of the first space
    while (space != -1) {//as long as there are spaces in the sentence
       if(Character.isUpperCase(sentence.charAt(space + 1))) { //if the first letter of the next word (after the space) is uppercase
          count++;//count it too!
       }
       space = sentence.indexOf(" ", space + 1);//continue updating the value for loc based on the next location of a space
    }
    
    System.out.println("There are " + count + " words that start with an uppercase letter.");

OR (using split method)

      String[] words = sentence.split(" ");

      int count = 0;

      for (int i = 0; i < words.length; i++) {
          if (Character.isUpperCase(words[i].charAt(0))) {
              count++;
          }
      }

      System.out.println(count);

7) 

    import java.util.Scanner;
    public class CountVowels {
        public static void main(String [] args) {
            Scanner sc = new Scanner (System.in);
            System.out.print("Enter a String: ");
            String s = sc.nextLine();
    
            int countVowels = 0;
    
            for(int i = 0; i < s.length(); i++) {
                char c = s.charAt(i); //OR convert to lowercase/uppercase to reduce comparisons by half
                if(c == 'A' || c == 'E' || c == 'I' || c == 'O' || c == 'U' || c == 'a' || c == 'e' || c == 'i' || c == 'o' || c == 'u') {
                    countVowels++;
                }
            }
    
            System.out.println("Number of vowels: " + countVowels);
    
        }
    }

----------------------------------------------------------------------------------------

DAY 2 

1) 

    import java.util.Scanner;
    public class IsPalindrome {
        public static void main(String [] args) {
            Scanner sc = new Scanner (System.in);
            System.out.print("Enter a String: ");
            String s = sc.next();
    
            String revS = "";
            for(int i = s.length()-1; i >= 0; i--) {
                revS += s.charAt(i);
            }
    
            System.out.println("String reversed: " + revS);
    
            if(s.equalsIgnoreCase(revS)) {
                System.out.println("This String is a palindrome.");
            } else {
                System.out.println("This String is nota palindrome.");
            }
        }
    }

2)

    public static void main(String[] args) throws Exception {
        File file = new File("Week9Emails.txt");
        Scanner scanner = new Scanner(file);
    
        System.out.println("Unique Domain Names:");
    
        while (scanner.hasNext()) {
             String first = scanner.next();
             String last = scanner.next();
             String email = scanner.next();
             String domain = email.substring(email.indexOf('@') + 1);
             System.out.println(domain);
        }
        scanner.close();
    }

3) first = (name1.compareTo(name2) < 0) ? name2 : name1;

4) 

    String word, prev;
    boolean isdup=false;
    n=0;
    prev=stdin.next();
    word=stdin.next();
    while (!word.equals("xxxxx")) {
    	if (word.equals(prev))
    		isdup=true;
    	else {
    		if (!isdup) n++;
    		isdup=false;
    	}
    	prev = word;
    	word=stdin.next();
    }
    if (!isdup) n++;

5)

    import java.util.Scanner;
    
    public class WordCounter {
        public static void main(String[] args) {
            Scanner sc = new Scanner(System.in);
    
            System.out.print("Enter a sentence: ");
            String sentence = sc.nextLine();
    
            String[] words = sentence.split(" ");
    
            System.out.println("Number of words: " + words.length);
        }
    }