Helidon 4.0.7: Parameters.first(String) generates java.lang.IndexOutOfBoundsException: Index 0 out of bounds for length 0

[hrstoyanov]

Environment Details

• Helidon Version: 4.0.7
• Helidon SE
• JDK version: 21.0.2
• OS: MacOS

The implementation of Parameters.first(String) has some issues: As it returns an optional value, it should never fail:

       var content = req.content();
        if(content.hasEntity()){
            var params = content.as(Parameters.class);
            var q = params.first("q");
            if(q.isPresent()) {
                ...
            }
        }

... and here is the failure stack trace:

Caused by: java.lang.IndexOutOfBoundsException: Index 0 out of bounds for length 0
	at java.base/jdk.internal.util.Preconditions.outOfBounds(Preconditions.java:100)
	at java.base/jdk.internal.util.Preconditions.outOfBoundsCheckIndex(Preconditions.java:106)
	at java.base/jdk.internal.util.Preconditions.checkIndex(Preconditions.java:302)
	at java.base/java.util.Objects.checkIndex(Objects.java:385)
	at java.base/java.util.ArrayList.get(ArrayList.java:427)
	at io.helidon.common.parameters@4.0.7/io.helidon.common.parameters.ParametersMap.get(ParametersMap.java:70)
	at io.helidon.common.parameters@4.0.7/io.helidon.common.parameters.ParametersMap.first(ParametersMap.java:101)

If you follow the stack trace, you will see the problem. My current workaround is to convert to a Map:

var content = req.content();
if(content.hasEntity()) {
     var params = content.as(Parameters.class).toMap();
      ...
}

[talios]

I hit something similar to this the other day and worked around it with:

var query = req.query();
if (!query.isEmpty() && query.get("period") instanceof String period) {

Having to check the isEmpty is kind-of a pain. Tho the out-of-bounds you got seems worse.

[hrstoyanov]

@talios have you tried:

var period = req.query().first("period").asString().orElse("whatever);

//or

req
    .query()
    .first("period")
    .asString()
    .ifPresent(period->{....});

[talios]

@hrstoyanov That works nicely - even better using .as(Period::parse) to map to the desired type. Much cleaner - cheers!