opencsv

问题 I am trying to simply import a .csv into Python. I've read numerous documents but for the life of me I can't figure out how to do the following. The CSV format is as follows NYC,22,55 BOSTON,39,22 I'm trying to generate the following : {NYC = [22,55], BOSTON = [39,22]} so that I can call i[0] and i[1] in a loop for each variable. I've tried import csv input_file = csv.DictReader(open("C:\Python\Sandbox\longlat.csv")) for row in input_file: print(row) Which prints my variables, but I dont know

问题 I have a csv id,name,description,price,date,name,address 1,SuperCsv,Write csv file,1234.56,28/03/2016,amar,jp nagar I want to read it and store it to json file. I have created two bean course(id,name,description,price,date) and person(name,address) on reading by bean reader i'm not able to set the person address. The (beautified) output is Course [id=1, name=SuperCsv, description=Write csv file, price=1234.56, date=Mon Mar 28 00:00:00 IST 2016, person=[ Person [name=amar, address=null],

问题 I have a CSV file with the following columns: id , fname , telephone , lname , address . I have a Person class with id , fname and lname data members. I want to map only these columns to Person object from a CSV file and discard telephone and address columns. How can I do this? The solution must scale as more columns are added in future. And should work regardless of column position. In an ideal solution user will only specify columns to read and it should just work. 回答1: You can use

问题 Suppose csv file contains 1,112,,ASIF Following code eliminates the null value in between two consecutive commas. Code provided is more than it is required String p1=null, p2=null; while ((lineData = Buffreadr.readLine()) != null) { row = new Vector(); int i=0; StringTokenizer st = new StringTokenizer(lineData, ","); while(st.hasMoreTokens()) { row.addElement(st.nextElement()); if (row.get(i).toString().startsWith("\"")==true) { while(row.get(i).toString().endsWith("\"")==false) { p1= row.get

问题 I am using the "ColumnPositionMappingStrategy" class of the opencvs library. This class has the deprecated method setType(Class<T> type) and as comment has " This method is deprecated as the user should use the Java 5 conventions " As far as I understand is that I have to use Generics instead of setType like: ColumnPositionMappingStrategy<MyClass> mappingStrategy = new ColumnPositionMappingStrategy<>(); to solve the problem. But I get NullPointerException when I remove the line:

问题 With OpenCSV, how do I append to existing CSV using a MappingStrategy? There are lots of examples I could find where NOT using a Bean mapping stategy BUT I like the dynamic nature of the column mapping with bean strategy and would like to get it working this way. Here is my code, which just rewrites the single line to CSV file instead of appending. How can I fix this? Using OpenCSV 4.5 . Note: I set my FileWriter for append=true . This scenario is not working as I expected. Re-running this

问题 I am using opencsv to parse csv file data which has been uploaded using web and populating the read data in the bean (using HeaderColumnNameTranslateMappingStrategy) which is working fine. But struggling to find best way to validate (as a first check) that if the file has all the headers before starting processing the data. Opencsv still process the file and populate null values in the bean when the file does not have all the headers that have been passed as a columnsMapping map. 回答1: So

问题 This is my code: CSVReader reader = new CSVReader(isReader); while ((col = reader.readNext()) != null) { String c1 = col[1]; } this is my csv file: "a","","c" "1",,"3" Is there a way I can differentiate between null and ""? OpenCSV seems to treat everything as non-null String. Can I tell it to treat empty fields as null? 回答1: It is not possible. There is no difference between an empty string and the java specific null in the CSV format's philosophy. The null is an empty reference in the java

问题 This is my code: CSVReader reader = new CSVReader(isReader); while ((col = reader.readNext()) != null) { String c1 = col[1]; } this is my csv file: "a","","c" "1",,"3" Is there a way I can differentiate between null and ""? OpenCSV seems to treat everything as non-null String. Can I tell it to treat empty fields as null? 回答1: It is not possible. There is no difference between an empty string and the java specific null in the CSV format's philosophy. The null is an empty reference in the java

问题 I need help with reading the folder and opening / outputting the csv data, I have used examples other people have written but none of them have worked for me. What I currently have is this, but it doesn't output the files: $files = scandir($PathToCreate.$version."/"); //scan the folder foreach($files as $file) { //for each file in the folder //The following is another example I found but does not output anything I just need to open each file and be able to output / target specific data $csv =