Optional null with Apache Camel to get header parameters

Good morning.

Currently I am developing an API in Apache Camel in which I have to use queryParameters for the query and some parameters may be mandatory and others not, so I need to handle in case I don’t send the parameter have some way to handle the nullPointerException, I was using Optional However, I don’t know if I’m using it incorrectly, but I’m not getting the error:

Currently I am using the following line that in theory if it receives a null value, it would return an empty optional, however, I get an error:

Optional<String> optionalServices= Optional.ofNullable(exchange.getIn().getHeader("services").toString());

Exception

Stacktrace
---------------------------------------------------------------------------------------------------------------------------------------: java.lang.NullPointerException: Cannot invoke "Object.toString()" because the return value of "org.apache.camel.Message.getHeader(String)" is null
    at org.tmve.customer.ms.processor.UserProfileProcessorQueryParamReq.process(UserProfileProcessorQueryParamReq.java:35)
    at org.apache.camel.support.processor.DelegateSyncProcessor.process(DelegateSyncProcessor.java:65)
    at org.apache.camel.impl.engine.CamelInternalProcessor.process(CamelInternalProcessor.java:392)
    at org.apache.camel.processor.Pipeline$PipelineTask.run(Pipeline.java:104)
    at org.apache.camel.impl.engine.DefaultReactiveExecutor$Worker.schedule(DefaultReactiveExecutor.java:181)
    at org.apache.camel.impl.engine.DefaultReactiveExecutor.scheduleMain(DefaultReactiveExecutor.java:59)
    at org.apache.camel.processor.Pipeline.process(Pipeline.java:165)
    at org.apache.camel.impl.engine.CamelInternalProcessor.process(CamelInternalProcessor.java:392)
    at org.apache.camel.component.platform.http.vertx.VertxPlatformHttpConsumer.lambda$handleRequest$2(VertxPlatformHttpConsumer.java:201)
    at io.vertx.core.impl.ContextBase.lambda$null$0(ContextBase.java:137)
    at io.vertx.core.impl.ContextInternal.dispatch(ContextInternal.java:264)
    at io.vertx.core.impl.ContextBase.lambda$executeBlocking$1(ContextBase.java:135)
    at org.jboss.threads.ContextHandler$1.runWith(ContextHandler.java:18)
    at org.jboss.threads.EnhancedQueueExecutor$Task.run(EnhancedQueueExecutor.java:2449)
    at org.jboss.threads.EnhancedQueueExecutor$ThreadBody.run(EnhancedQueueExecutor.java:1478)
    at org.jboss.threads.DelegatingRunnable.run(DelegatingRunnable.java:29)
    at org.jboss.threads.ThreadLocalResettingRunnable.run(ThreadLocalResettingRunnable.java:29)
    at io.netty.util.concurrent.FastThreadLocalRunnable.run(FastThreadLocalRunnable.java:30)
    at java.base/java.lang.Thread.run(Thread.java:840)

This is how I am testing from postman when it does not send the value:

In this case, how can I handle the value of the Query Parameters if it is not sent?

>Solution :

According to the error log, it is , Message.getHeader(String) returns null.

Your statement could be corrected as the following.

Optional<String> optionalServices= Optional.ofNullable(exchange.getIn().getHeader("services"))
                .map(Object::toString)

If I explain the above in multiple steps.

Optional<Object> optObj = Optional.ofNullable(exchange.getIn().getHeader("services")); 
Optional<String> optStr = optObj.map(obj -> obj.toString());

So, the function (obj -> obj.toString()) within Optional.map() is called only when Optional has a value.