HttpClient exceptionHandler exception is always null

[Niraj Chauhan]

I am trying to handle exception in exceptionHandler of HttpClient. Here is my code:

HttpEndpoint.getClient(serviceDiscovery, new JsonObject().put("name","tweets"), endPoint -> {
    if(endPoint.failed()){
        log.error("Failed getting discovery", endPoint.cause());
    }else{
        HttpClient client = endPoint.result();
        client.get("/v1/api/tweets", response -> {
            response.bodyHandler(body -> routingContext.response().end(body.toString()));
        })
                .setTimeout(2000)
                .exceptionHandler(e -> {
                    log.error("Exception: " + e.getCause());
                    routingContext.response().end("Error");
                })
                .end();
    }
});

Here is the log output:

Apr 09, 2017 10:51:01 AM com.tweets.Routes
SEVERE: Exception: null

I have stopped the end service to get the exception.

[Tim Fox]

You are logging the cause of the exception not the exception itself, the exception itself is not null otherwise you would have got a NPE.

Not all exceptions have non null causes.

[Thomas SEGISMONT]

You get a NPE because e.getCause is null...

Change your code to log.error("Exception", e);

2017-04-09 12:51 GMT+02:00 Niraj Chauhan <nirajm...@gmail.com>:

The exception itself is null, when I changed my code to

log.error("Exception: " + e.getCause().getMessage());

I got NPE(Routes.java:63 is the log.error).

Apr 09, 2017 4:18:16 PM io.vertx.core.impl.ContextImpl
SEVERE: Unhandled exception
java.lang.NullPointerException
    at com.tweets.Routes.lambda$null$5(Routes.java:63)
    at io.vertx.core.http.impl.HttpClientRequestBase.handleException(HttpClientRequestBase.java:136)
    at io.vertx.core.http.impl.HttpClientRequestImpl.handleException(HttpClientRequestImpl.java:51)
    at io.vertx.core.http.impl.HttpClientRequestImpl$2.handleFailure(HttpClientRequestImpl.java:707)
    at io.vertx.core.http.impl.ConnectionManager$ConnQueue.lambda$connectionFailed$3(ConnectionManager.java:368)
    at io.vertx.core.impl.ContextImpl.lambda$wrapTask$2(ContextImpl.java:335)
    at io.vertx.core.impl.ContextImpl.executeFromIO(ContextImpl.java:193)
    at io.vertx.core.http.impl.ConnectionManager$ConnQueue.connectionFailed(ConnectionManager.java:362)
    at io.vertx.core.http.impl.ConnectionManager$ConnQueue.access$1900(ConnectionManager.java:194)
    at io.vertx.core.http.impl.ConnectionManager$ChannelConnector.lambda$connect$2(ConnectionManager.java:528)
    at io.vertx.core.net.impl.ChannelProvider.lambda$connect$0(ChannelProvider.java:42)
    at io.netty.util.concurrent.DefaultPromise.notifyListener0(DefaultPromise.java:507)
    at io.netty.util.concurrent.DefaultPromise.notifyListeners0(DefaultPromise.java:500)
    at io.netty.util.concurrent.DefaultPromise.notifyListenersNow(DefaultPromise.java:479)
    at io.netty.util.concurrent.DefaultPromise.notifyListeners(DefaultPromise.java:420)
    at io.netty.util.concurrent.DefaultPromise.tryFailure(DefaultPromise.java:122)
    at io.netty.channel.nio.AbstractNioChannel$AbstractNioUnsafe.fulfillConnectPromise(AbstractNioChannel.java:327)
    at io.netty.channel.nio.AbstractNioChannel$AbstractNioUnsafe.finishConnect(AbstractNioChannel.java:343)
    at io.netty.channel.nio.NioEventLoop.processSelectedKey(NioEventLoop.java:630)
    at io.netty.channel.nio.NioEventLoop.processSelectedKeysOptimized(NioEventLoop.java:565)
    at io.netty.channel.nio.NioEventLoop.processSelectedKeys(NioEventLoop.java:479)
    at io.netty.channel.nio.NioEventLoop.run(NioEventLoop.java:441)
    at io.netty.util.concurrent.SingleThreadEventExecutor$5.run(SingleThreadEventExecutor.java:858)
    at java.lang.Thread.run(Thread.java:745)

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[Niraj Chauhan]

Thanks, it worked now :)

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