I am trying to take heap dump using below 2 commands jcmd $pid GC.heap_dump /tmp/filename.dump jmap -dump:format=b,file=/tmp/filename.dump $pid jcmd produces file size of ~300M and jmap produces file size of ~1.4G. why these are different sizes, do we have any additional information in jmap ? am I missing some arguments in jcmd ? JDK is 1.8.0_162 Xms and Xmx is
Tag: java-8
How to map an OptionalLong to an Optional?
I have an instance of OptionalLong. But one of my libraries requires an Optional<Long> as a parameter. How can I convert my OptionalLong into an Optional<Long>? I was dreaming about something like this: Answer I don’t know simpler solutions but this will do what you need.
Minimum Spring version compatible with Java 11
I need to upgrade an app to Java 11 very soon, I was wondering what’s the minimum Spring version that is compatible with Java 11. I’m currently using Java 8 and Spring 4.2.7. Answer From their task tracker — SPR-16391:Compatibility with JDK 11. The compatibility of JDK 10, 11 is planned along with 5.1 GA release. JDK 11 is currently
Counting items from Map having Set as value
I have a list of items as below Now I am converting this list into here complexList gives output as Now I need to count number of values for each “capacity” giving output as I tried and it outputs I must be mistaking in understanding streams or not be using right methods. Can anyone suggest an approach or a solution?
Apache HttpClient – Log version of TLS that’s negotiated in a request?
I’ve got lots of code that uses Apache’s HttpClient, and I’d like to log the version of TLS that’s being negotiated when a request is made. Is this possible? I’d prefer an approach that doesn’t requiring changing how the request is being built, if possible – something that inspects a response or views a log or something like that? From
Convert ZonedDateTime to LocalDateTime at time zone
I have an object of ZonedDateTime that is constructed like this How can I convert it to LocalDateTime at time zone of Switzerland? Expected result should be 16 april 2018 13:30. Answer How can I convert it to LocalDateTime at time zone of Switzerland? You can convert the UTC ZonedDateTime into a ZonedDateTime with the time zone of Switzerland, but
logging in interface methods
I have been working on java 7 so far and recently moved to java-8, one thing which was surprising is that you can add methods in java-8 interfaces. So far so good….loved this new stuff! Now, my problem is that logging is an essential part of any development but seems lombok.extern.slf4j won’t let you add log stuffs in by interface
Count the same items in a row in Java 8 Stream API
I have a bean and a stream and want to apply some intermediate operation to the stream that returns another stream of objects of TokenBag. In this example there must be two: (“a”, 3), (“b”, 3) and (“a”, 2). Please think it as a very simplistic example. In real there will be much more complicated logic than just counting the
What is the difference between intermediate and terminal operations?
can someone tell me What is the difference between intermediate and terminal operations for Stream? Stream operations are combined into pipelines to process streams. All operations are either intermediate or terminal ..means?. Answer A Stream supports several operations and these operations are divided into intermediate and terminal operations. The distinction between this operations is that an intermediate operation is lazy
How to move from deprecated Task to ApiFuture for firebase admin SDK 5.4 and above
I’m just trying to solve the deprecation notes from my Java code of new firebase-admin SDK, the code is written in version 5.3.1 but after upgrading the version into 5.5.0 the deprecation notes appeared, here is a sample of my code: Using FirebaseAuth (deprecatation on: Task, addOnSuccessListener and addOnFailureListener) : And for FirebaseDatabase (deprecatation on: Task, addOnSuccessListener, addOnFailureListener, updateChildren and