Q.When is a switch statement preferable to an if...else if ladder? Rewrite the following as a switch:

if (choice == 1) System.out.println("Add");  
else if (choice == 2) System.out.println("Subtract");  
else System.out.println("Invalid");  

When one variable is compared against several fixed values, a switch reads more clearly than a long ladder. …

When to prefer switch. An if...else if ladder can test any conditions (ranges, combinations, different variables). But when the logic is simply "compare one variable against several fixed constant values", a switch is cleaner and easier to read, because the variable is written once and each possible value is a labelled case.

Rewritten as a switch:

switch (choice) {
    case 1:
        System.out.println("Add");
        break;
    case 2:
        System.out.println("Subtract");
        break;
    default:
        System.out.println("Invalid");
}

Points to note:

• Each case gives one value of choice to match.
• break is essential at the end of each case; it makes control leave the switch. Without break, execution "falls through" into the next case and runs its code too. …

Omitting break, which causes fall-through so more than one message prints. Trying to use ranges like case marks >= 75 — `case …