How to use null in switch

Question

Integer i = ...

switch (i){
    case null:
        doSomething0();
        break;    
    }

In the code above I cant use null in switch case state

Answer 1

Java docs clearly stated that:

The prohibition against using null as a switch label prevents one from writing code that can never be executed. If the switch expression is of a reference type, such as a boxed primitive type or an enum, a run-time error will occur if the expression evaluates to null at run-time.

You must have to verify for null before Swithch statement execution.

if (i == null)

See The Switch Statement

case null: // will never be executed, therefore disallowed.

Answer 2

This is not possible with a switch statement in Java. Check for null before the switch:

if (i == null) {
    doSomething0();
} else {
    switch (i) {
    case 1:
        // ...
        break;
    }
}

You can't use arbitrary objects in switch statements^*. The reason that the compiler doesn't complain about switch (i) where i is an Integer is because Java auto-unboxes the Integer to an int. As assylias already said, the unboxing will throw a NullPointerException when i is null.

^* Since Java 7 you can use String in switch statements.

More about switch (including example with null variable) in Oracle Docs - Switch

Answer 3

Based on @tetsuo answer, with java 8 :

Integer i = ...

switch (Optional.ofNullable(i).orElse(DEFAULT_VALUE)) {
    case DEFAULT_VALUE:
        doDefault();
        break;    
}

Answer 4

switch ((i != null) ? i : DEFAULT_VALUE) {
        //...
}

Answer 5

switch(i) will throw a NullPointerException if i is null, because it will try to unbox the Integer into an int. So case null, which happens to be illegal, would never have been reached anyway.

You need to check that i is not null before the switch statement.

Answer 6

switch (String.valueOf(value)){
    case "null":
    default: 
}