I'm on course and we've recently started learning Java. I've got a task identify pangrams using switch-cases and booleans. The task states:

1. Create a String ‘sentence’ with the value “Sixty zippers were quickly picked from the woven jute bag.”

2. Create 26 Boolean variables named a to z

   a. Boolean a, b, … y, z;

   b. a, b, … y, z = true;

3. Create a loop that will iterate over each letter of the sentence

   a. Be careful of the iterator you use within your loop as the letter ‘i’ will already be taken!

4. Using switch-cases and the Booleans you made, identify the letter and set the corresponding Boolean to true.

5. Once the sentence has been fully processed, evaluate the value of each Boolean:

   a. Should all of them be true, print the message ‘the sentence “” is a pangram!’

   b. Should any of them be false, print the message ‘the sentence “” is not a pangram!’

I'm not sure if it's just the wording of the task that's tripping me up, but I'm not sure how to execute it. This is what I've got at the moment:

String sentence = "Sixty zippers were quickly picked from the woven jute bag.";
        Boolean a, b, c, d, e, f, g, h, i, j, k, l, m, n, o, p, q, r, s, t, u, v, w, x, y, z;
        
        a = b = c = d = e = f = g = h = i = j = k = l = m = n = o = p = q = r = s = t = u = v = x = y = z = true;
        
            for (int letter = sentence.length() - 1; letter <= 0; letter  ) {
                
                int character = sentence.charAt(letter);
                
                switch(character) {
                case a:
                case b:
                case c:

When I do the case like this, obviously it won't convert, so how would I evaluate each character?

CodePudding user response：

As pointed out in the comments, the for loop is not correct. To iterate over the characters in order:

for (int letter = 0; letter < sentence.length(); letter  ) {

When fetching a character from the string, convert it to lower case (otherwise, you'd need a separate case for both 'a' and 'A'):

char character = Character.toLowerCase(sentence.charAt(letter)); 

The switch statement:

switch(character) {
    case 'a': 
        a = false; 
        break; // needed to avoid fall-through to case 'b'
    case 'b': 
        b = false; 
        break; 
    ...

Now you can test if all variables were set to false:

boolean isPangram = !a && !b && ... && !z;

The code would be simpler and clearer if the variables were set to false in the beginning and to true in the loop.

CodePudding user response：

You have a lot wrong in an incomplete solution. This looks like a school assignment so I'm not writing code but here are some things you should address.

• Do not initialize your boolean flags to true. Set them to true when you encounter that character.
  • you may want to change the type of the flags to be primitive boolean and/or you will want to initialize them to false.
• You've defined character as an int but it should really be a char
  • note that using an int will work due to implicit casting but it may prove confusing.
• The cases names should be in single quotes to indicate they are characters rather than the variables you defined at the beginning.
• within each case, set the appropriate flag and break to prevent fall-through assignments
• the for-loop is set up wrong. You are starting at the end and increment so it will stop immediately.
  • start at the beginning (i.e. initialize letter to 0)
  • change the condition to cover the length of the String
  • the incrementor is fine.