I’m new to Java, and I am facing this issue in Eclipse. Even after pointing it to the correct file, it shows a file not Found Error. I am trying to compile code from a Java file using the Java Compiler API. The code words fine in Visual Studio with setting everything in root, But gives this error in Ecl…
Tag: java
Initialize a Linked List nodes using map().reduce()
I want to do this initialization of the Node class using java streams. How do I do this using the map and reduce stream operations? I’ve tried something like this, which does not compile I want to map each element in the array to Node(int i , Node n) and then reduce it to a Node. What am I missing
Hibernate Validator: Method constraints not evaluated
I have a simple class, which I’d like to validate: This class is validated as part of the inputs of a spring controller method. I managed to configure the validation of the fields (someField in this case), but for some reason the methodConstraint() isn’t even invoked, let alone validated. I rememb…
Is there any way to use something like List.class?
I’m using SpringBoot with OpenAPI and SwaggerUI to implement a rest api. I want to annotate a @GetMapping method with @ApiResponses to provide the schema of the response, but I’m struggling with the parameter implementation of @Schema. The return type of my method is List<ScanDTO>, so I trie…
What is the best way to produce events with current time timestamps in Flink?
I am trying to understand what is the best way to achieve current time timestamps using Flink when producing a new record to Kafka Does flink automatically fill the produced event with metadata containing the timestamp of the current time? Is that the best practice for the consumers or should we put the curre…
Reasons why a JAR on classpath not loaded
I have a SpringBoot application that is run with the command java -classpath <longlist of JARs> com.example.MyApp. I have the path to a JAR – in this case liquibase-core-4.4.0.jar – specified on the classpath. However, on startup the app complains about missing class definitions. Attaching a…
Universal solution to insert Userinput values in MySQL database with a priori unknown columns with Java and for example PreparedStatements
I want to insert a whole set of values in my table in MySQL (e.g. This works in MySQL Workbench 8.0 but not in my Java Code. I read the JavaDoc about prepared Statements but I didn’t find any clues on inserting values if I don’t know the type a priori. My Java code looks like this: I tried many
java.lang.NumberFormatException: For input string: “5.3”
when running this code i am getting this java.lang.NumberFormatException: For input string: “5.3” Exception. how can we resolve this type of exception.any other way we can handle this without try and catch? value can be any thing.it’s not fixed that it will always be float.it can be integer …
ModelMapper returning source object type when mapping derived class to a base class
Let’s suppose I have classes: I have an instance of B called b and want to map to A (to get rid of z property as it’s getting serialized later). I was trying to do; But as a result I am getting the the same type B object. I suspect it could be because B is a subclass of A,
@Value not getting the value from application.properties
im trying to get a value from the application.properties in a Spring boot app. The class is defined with the tag @Component, I already tried @Service too, and with @PropertySource(“classpath:application.properties”) and without the @PropertySource but in any case they get the value. The interface …