NullPointerException crash in Java API

[njbartlett]

In the Java API, the following code works:

private final Gauge fillLevelGauge = Gauge.build()
        .name("fill_level")
        .help("Fill level")
        .register();

    // ...

    fillLevelGauge.set(1d);

... but the following code crashes with a NullPointerException:

private final Gauge fillLevelGauge = Gauge.build()
        .name("fill_level")
        .labelNames("mylabel")
        .help("Fill level")
        .register();

    // ...

    fillLevelGauge.set(1d);

I found the following issue which states "for a labelled metric you must specify the labels". However I cannot believe that you actually intend for the program to crash when a programmer makes this mistake? And not even with any explanation of the reason for the crash?

At the very least I believe this should be an IllegalArgumentException with a message attached, e.g. "for a labelled metric you must specify the labels".

[krasi-georgiev]

@njbartlett shouldn't this be in the java client issues?
https://github.com/prometheus/client_java

[njbartlett]

@krasi-georgiev Sorry yes, I will move it.

[lock]

This thread has been automatically locked since there has not been any recent activity after it was closed. Please open a new issue for related bugs.