So, In college we are working with csv files and streams. Right now I am doing some homework but I’ve been stuck in this exercise for some days now. I have a csv file with some data about accidents (like the accident severity, the number of victims and so) and I have a function that reads that data and converts
Tag: stream
How to match equals() and hashCode in streams?
I have a stream where I am aggregating some data like this: The problem is that by adding this comparator I am braking the contract between hashCode() and equals() and at the end I have duplicate keys: Has anyone some ideas how can I fix this? Or is there a way to sort the final object ( Map<String, Map<String, Map<EventType,
Set with Optional
I have this code: I want to replace this code to this: and map this field from myClass to myClass2 How i can do it? Answer Did you mean to use: For mapping I would suggest to read about MapStruct, it is a good tool.
How to use stream to filter objects from HashSet that have empty value for certain fields?
I am looking for a way to filter only the Worker objects with a specific first name and empty lastName from the given HashSet. For example I want the code to return the record with firstName == scott and lastName == “”. Answer filter is a non-terminal operation and the stream would be processed only when a terminal operation is
Is there a way to reduce multiple methods as one method with Function as methode parameter?
I have several methods that are basically all the same except for one method that is called in these methods. Example: So the only difference is the method getDB(). Since I don’t want to have this method 10 times, I thought of writing this into a method and then controlling it via the input parameters. My attempt looks like this:
Sort A List of an Object with other object’s method
In the bellow code, with such classes, how can I sort an ArrayList of Students by the score the got from Courses List? I mean how can I sort a List of a specific class by an attribute of this class which is a child of another class. Answer Your “Student” class is confusing. Based on the name, it sounds
How to properly decode and encode characters from JTextArea
I have a program that works on a console, and i want to make a custom console for it. Current command line interface can be started with a method that takes an InputStream and PrintStream as arguments….
‘ZipException: invalid code lengths set’ when streaming input file to Apache-POI
I’m attempting to create an xlsx workbook object with Apache-POI by passing my .xlsx as a resource stream: I can successfully instantiate the workbook when passing my template.xlsx through a FileInputStream and a local file path, but when I pass the resources stream I get an exception: The .xlsx I’m passing shouldn’t be zipped, but maybe that’s how it works
How to redirect ProcessBuilder’s output to a string?
I am using the following code to start a process builder.I want to know how can I redirect its output to a String. I tried using ByteArrayOutputStream but it didn’t seem to work. Answer Read from the InputStream. You can append the output to a StringBuilder:
How do I read / convert an InputStream into a String in Java?
If you have a java.io.InputStream object, how should you process that object and produce a String? Suppose I have an InputStream that contains text data, and I want to convert it to a String, so for …