java switch Constant expression required

In Java, the switch statement requires a constant expression as its argument. A constant expression is an expression whose value can be determined at compile-time and does not change during the execution of the program. It means that the value being tested in the switch statement must be a constant, like a literal value or a final variable.

If you encounter the error message "Constant expression required" in a switch statement, it means that the value you provided is not considered a constant expression. To resolve this issue, you can try using if-else statements instead of a switch statement or ensure that the value being tested meets the criteria of a constant expression.

Here's an example of a switch statement with a constant expression:

final int num = 2;
switch (num) {
    case 1:
        // code for case 1
        break;
    case 2:
        // code for case 2
        break;
    default:
        // code for default case
}

In this example, the variable `num` is declared as `final`, making it a constant. Hence, it can be used in the switch statement.