I need to write a program which takes a user input of any month and returns the number of days in said month. Here is the code that i wrote.

    Scanner keyboard = new Scanner(System.in);
    out.print("Enter month : ");
    String month = keyboard.nextLine().toLowerCase();
    switch (month){
        case "january" :
            out.println("31 days");
            break;

        case "february" :
            out.println("");
            out.print("Is it a leap year (yes/no): ");
            String leap_year = keyboard.nextLine().toLowerCase();
            if (leap_year.equals("no")){
                out.println("28 days");
                break;
            } if (leap_year.equals("yes")){
                out.println("29 days");
                break;  
            } else{
                out.println("Invalid option.. Use yes/no only.");
                break;
            }
            
        case "march" :
            out.println("31 days");
            break;
        case "april" :
            out.println("30 days");
            break;

        case "may" :
            out.println("31 days");
            break;
        case "june" :
            out.println("30 days");
            break;

        case "july" :
            out.println("31 days");
            break;

        case "august" :
            out.println("31 days");
            break;

        case "september" :
            out.println("30 days");
            break;

        case "october" :
            out.println("31 days");
            break;

        case "november" :
            out.println("30 days");
            break;

        case "december" :
            out.println("31 days");
            break;
        default :
            out.println("Enter a correct month");
            break;

    }
    keyboard.close();

This code works properly but it seems quite dragged-out. Is there a way i can use or operator to make this code concise. Other suggestions are also appreciated. Thanks :D

CodePudding user response：

To answer your question directly:

Is there a way to use logical or ( || ) in switch case?

No, it doesn't work with the || operator. But there are other ways to do what you are after.

You can collapse all cases with the same body together:

switch (month){
    case "january" :
    case "march" :
    case "may" :
    case "july" :
    case "august" :
    case "october" :
    case "december" :
        out.println("31 days");
        break;

    case "february" :
        out.println("");
        out.print("Is it a leap year (yes/no): ");
        String leap_year = keyboard.nextLine().toLowerCase();
        if (leap_year.equals("no")){
            out.println("28 days");
            break;
        } if (leap_year.equals("yes")){
        out.println("29 days");
        break;
    } else{
        out.println("Invalid option.. Use yes/no only.");
        break;
    }

    case "april" :
    case "june" :
    case "september" :
    case "november" :
        out.println("30 days");
        break;

    default :
        out.println("Enter a correct month");
        break;
}

Or use the new switch syntax if you're using Java 14 or newer:

switch (month) {
    case "january", "march", "may", "july", "august", "october", "december" -> out.println("31 days");
    case "february" -> {
        out.println("");
        out.print("Is it a leap year (yes/no): ");
        String leap_year = keyboard.nextLine().toLowerCase();
        if (leap_year.equals("no")) {
            out.println("28 days");
            break;
        } else if (leap_year.equals("yes")) {
            out.println("29 days");
        } else {
            out.println("Invalid option.. Use yes/no only.");
        }
        break;
    }
    case "april", "june", "september", "november" -> out.println("30 days");
    default -> out.println("Enter a correct month");
}