Null object: Difference between revisions
Content added Content deleted
| Line 730: | Line 730: | ||
<syntaxhighlight lang="java"> |
<syntaxhighlight lang="java"> |
||
module NullObject |
module NullObject { |
||
{ |
void run() { |
||
void run() |
|||
{ |
|||
@Inject Console console; |
@Inject Console console; |
||
console.print($"Null value={Null}, Null.toString()={Null.toString()}"); |
console.print($"Null value={Null}, Null.toString()={Null.toString()}"); |
||
| Line 746: | Line 744: | ||
console.print($"len={len}"); |
console.print($"len={len}"); |
||
if (String test ?= s) |
if (String test ?= s) { |
||
{ |
|||
// "s" is still Null in this test, we never get here |
// "s" is still Null in this test, we never get here |
||
} else { |
|||
else |
|||
{ |
|||
s = "a non-null value"; |
s = "a non-null value"; |
||
} |
|||
// if (String test ?= s){} // <-- compiler error: The expression type is not nullable: "String" |
// if (String test ?= s){} // <-- compiler error: The expression type is not nullable: "String" |
||
s2 = s; // at this point, s is known to be a non-null String |
s2 = s; // at this point, s is known to be a non-null String |
||
console.print($"s={s}, s2={s2}, (s==s2)={s==s2}"); |
console.print($"s={s}, s2={s2}, (s==s2)={s==s2}"); |
||
} |
|||
} |
} |
||
} |
|||
</syntaxhighlight> |
</syntaxhighlight> |
||