Java OCA OCP Practice Question 2433

Question

Given the following code, which of the optional lines of code can individually replace the //INSERT CODE HERE line so that the code compiles successfully? 

public class Main { 
    public static void main(String args[]) { 
        int num = 10; 
        final int num2 = 20; 
        switch (num) { 
            // INSERT CODE HERE 
            break; 
            default: System.out.println("default"); 
        } //from www.j a v  a2s.co m
    } 
}
  • a case 10*3: System.out.println(2);
  • b case num: System.out.println(3);
  • c case 10/3: System.out.println(4);
  • d case num2: System.out.println(5);


a, c, d

Note

Option (a) is correct.

Compile-time constants, including expressions, are permissible in the case labels.

Option (b) is incorrect.

The case labels should be compile-time constants.

A non- final variable isn't a compile-time constant because it can be reassigned a value during the course of a class's execution.

Although the previous class doesn't assign a value to it, the compiler still treats it as a changeable variable.

Option (c) is correct.

The value specified in the case labels should be assignable to the variable used in the switch construct.

You may think that 10/3 will return a decimal number, which can't be assigned to the variable num, but this operation discards the decimal part and compares 3 with the variable num.

Option (d) is correct.

The variable num2 is defined as a final variable and assigned a value on the same line of code, with its declaration.

Hence, it's considered to be a compile-time constant.




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