Questions tagged [switch-expression]
In C# and Java switch expressions are an alternative to the switch statement that returns a value.
switch-expression
66
questions
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Why is my JSP code with a switch expression not working?
I'm trying to run this JSP code but it doesn't work, I get HTTP Status 500. Why? Aren't switch expressions supported? I do not want to use a switch statement, so please do not tell me to use this old ...
- 19
0
votes
1
answer
50
views
Switch expression vs switch statement which one to use [closed]
Java 14 standardized switch expression and since Java 17 they have enhanced the switch expression to include pattern matching.
Is there any guideline to when one should be using switch statement vs ...
- 31
1
vote
3
answers
213
views
Can a Java 21 switch expression have multiple guards?
I have the following type for a command-line argument lexer (inspired by lexopt)
private sealed interface Opt permits ShortOpt, LongOpt, MiscOpt {}
record ShortOpt(char opt) implements Opt {} // the &...
- 196
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votes
1
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85
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using multiple statements in switch expression is giving CS0201 error [closed]
Below C# switch expression is giving Compiler Error
CS0201 Only assignment, call, increment, decrement, and new object expressions can be used as a statement
Not sure what is wrong here?
In this ...
- 37
4
votes
3
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141
views
Why do I need an explicit downcast in an exhaustive switch expression?
Here's some dart code that seems interesting to me:
void main() {
A<num> someA = B();
A value = switch (someA) {
B() => B(),
C() => C(),
};
}
sealed class A<T extends ...
- 327
2
votes
1
answer
193
views
Why Must Variables used in Guarded Pattern Case Labels be Final/Effectively Final? (Java 21)
With the new Java 21 features, we have better Pattern Matching. With these features, we have guarded pattern case labels, where one can define a pattern guard for case labels that looks like the ...
- 73
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1
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CA1508: 'null => true' is always 'true'. Remove or refactor the condition(s) to avoid dead code
I'm encountering an interesting scenario with the CA1508 warning in C# when using a switch expression with a nullable DateTime property. Specifically, I have a property that determines if there are ...
0
votes
1
answer
65
views
Why does C# pattern matching return float for this?
Here is the source code
bool v = false;
object x = v switch {
true => 0.0f,
false => 100L,
};
the pattern match returns different numeric types for the 2 branches, and the values is ...
- 191
0
votes
1
answer
103
views
How to use a switch expression to match a value where it equals another non-constant value [duplicate]
I want to write a method that converts a WPF System.Windows.FontWeight property to its equivalent CSS value using C#11. A switch expression seems the most appropriate construct. Here's my attempt:
...
- 6,688
0
votes
0
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100
views
SonarLint: Why does this condition always evaluates to true?
I'm writing a generic extension function which parses a string value to other types. The function basically looks like this:
public static T Parse<T>(string input)
{
T result = (T)(typeof(T) ...
- 370
0
votes
2
answers
66
views
Super weird behavior of C# switch expression [duplicate]
I encountered a very strange behavior of the C# switch expression, which I have no idea how to explain. So, I am practicing solving general interview problems, and today it was Kth Largest Element in ...
- 1,320
3
votes
2
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147
views
How to use indexers in switch expression?
How to access indexers in switch expression? There is a nice property pattern syntax in switch expressions, but I can't figure out or find any information about using indexers.
Given following code:
...
- 21.6k
3
votes
3
answers
935
views
Why was the yield keyword introduced for switch expressions? (not just use return keyword)
When a return statement occurs within a lambda expression, it simply
causes a return from the lambda. It does not cause an enclosing method
to return.
So, for switch expressions why the keyword yield ...
- 2,124
1
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1
answer
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views
How to tell quarkus to use java 17?
I keep gettring build error saing that I'm using a preview feature (switch expressions):
Service.java:28: error: patterns in switch statements are a preview feature and are disabled by default.
...
- 133
3
votes
1
answer
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views
Is this a C# switch expression exhaustiveness check bug?
public enum Test { Yes, No }
I have these two switch expressions. The one below gives a CS8509 warning:
Test? test = null;
var result = test switch
{
null => "Null",
Test.Yes =&...
- 2,248