Switch statement with boolean expressions in case labels

Question

I am learning java and I am having trouble with switch-case statement with expression. Can someone help me please? I am not able to understand where I am making the mistake.

package SecondSet_StartingArray;

import java.util.Scanner;

public class Testing 
{
    public static void main(String[] args) {

    System.out.println("Enter a Number between 1 & 100");
    Scanner scan = new Scanner(System.in);
    int i = scan.nextInt();
    switch (i)
    {
        case (i>90):    System.out.println("Rating 5");break;
        case (i<=90):   System.out.println("Rating 4");break;
        case (i<=60):   System.out.println("Rating 3");break;
        case(i<=30):    System.out.println("Rating 2");break;
        case(i>29):     System.out.println("Rating 1");break;
    }
}

}

switch cases require a concrete value, not a condition like `i<=90`. If you have conditions create an `if else if else if ... construction. — Robert, Feb 21 '18 at 13:40
Is there a easy way other than using case 100:case 99 : .... : case 91 .. — anonymous coder, Feb 21 '18 at 13:45
Just based on the logic of the current code you can get the rating by: `int rating = i/30 + 1` — ESipalis, Feb 21 '18 at 13:47

score 7 · Answer 1 · answered Feb 21 '18 at 13:40

You can't use switch-case with boolean expressions like case (i<=90). Your cases must be constant expressions to be evaluated.

case 90: whatever; break;
case 120: whatever; break;
case SOME_CONSTANT: whatever; break;

For your needs, you would need to use if-else-if statements.

score 2 · Answer 2 · answered Feb 21 '18 at 13:41

2

What you are trying to realize is an if-else-statement. Switch-Statements are used when you try to evaluate constant values.

answered Feb 21 '18 at 13:41

Michael Seiler

650
1
5
15

Many Thanks , I have tried if else statement , I am just trying to figure out if there is a option in case statement , as it makes simpler . – anonymous coder Feb 21 '18 at 13:52

Przemysław Moskal · Answer 3 · 2018-02-21T14:00:22.667

As you can read in Java Language Specification here:

All of the following must be true, or a compile-time error occurs:

Every case constant expression associated with a switch statement must be assignable (§5.2) to the type of the switch Expression.
No two of the case constant expressions associated with a switch statement may have the same value.
No switch label is null.
At most one default label may be associated with the same switch statement.

In your code the first point is not satisfied. You might want to use if-else-if statement instead of switch here to perform proper checking of value stored in i.

Switch statement with boolean expressions in case labels

3 Answers3