Java API to make an object from a CSV file [closed]

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I'm looking for a library that allows me to map a .csv contents to an object.

Something like:

public class Person {

    private String name;
    private int age;

    @CsvField("name")
    public String getName() {
        return this.name;
    }

    @CsvField("age")
    public int getAge() {
        return this.age;
    }
}

and then say something like:

final Person filledWithDataFromCsv = csvApi.load(csvFilepath, Pe开发者_开发知识库rson.class);

from the given CSV:

#name, age
tom, 11
jim, 32

Does anyone know of such an API, or one that does something similar. I don't want it to use annotations as a must, I just want to be able to load the file with one line of code and a predefined class.

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JSefa allow you to annotate Java classes that can be used in a serialization and de-serialization process. The tutorial demonstrates how this works with the CsvIOFactory class.

(From the tutorial) Annotating a bean is as simple as specifying the locations of the items in the list of values, and if necessary, you'll need to specify the conversion format:

@CsvDataType()
public class Person {
    @CsvField(pos = 1)
    String name;

    @CsvField(pos = 2, format = "dd.MM.yyyy")
    Date   birthDate;
}

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I prefer opencsv, it is ultra simple and very clean.

http://opencsv.sourceforge.net/

For example reading:

CSVReader reader = new CSVReader(new FileReader("yourfile.csv"));
String [] nextLine;
while ((nextLine = reader.readNext()) != null) {
    // nextLine[] is an array of values from the line
    System.out.println(nextLine[0] + nextLine[1] + "etc...");
}

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You can't go wrong with uniVocity-parsers. It supports all sorts of powerful operations and it is much faster than any other CSV parser for Java.

Here's a class with some examples:

class TestBean {

    // if the value parsed in the quantity column is "?" or "-", it will be replaced by null.
    @NullString(nulls = { "?", "-" })
    // if a value resolves to null, it will be converted to the String "0".
    @Parsed(defaultNullRead = "0")
    private Integer quantity;   // The attribute type defines which conversion will be executed when processing the value.

    @Trim
    @LowerCase
    // the value for the comments attribute is in the column at index 4 (0 is the first column, so this means fifth column in the file)
    @Parsed(index = 4)
    private String comments;

    // you can also explicitly give the name of a column in the file.
    @Parsed(field = "amount")
    private BigDecimal amount;

    @Trim
    @LowerCase
    // values "no", "n" and "null" will be converted to false; values "yes" and "y" will be converted to true
    @BooleanString(falseStrings = { "no", "n", "null" }, trueStrings = { "yes", "y" })
    @Parsed
    private Boolean pending;
}

Here's how to get a list of TestBean

BeanListProcessor<TestBean> rowProcessor = new BeanListProcessor<TestBean>(TestBean.class);

CsvParserSettings parserSettings = new CsvParserSettings();
parserSettings.setRowProcessor(rowProcessor);
parserSettings.setHeaderExtractionEnabled(true);

CsvParser parser = new CsvParser(parserSettings);
parser.parse(getReader("/examples/bean_test.csv"));

List<TestBean> beans = rowProcessor.getBeans();

Disclosure: I am the author of this library. It's open-source and free (Apache V2.0 license).

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There are pretty good JDBC implementations for CSV. So you can make use of such a driver, configure a datasource to use it and then use JPA (or whatever) for object-relational mapping on top of that data source.

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SimpleFlatMapper can do that easily see Getting Started csv using the headers of the csv or by manually specifying which columns map to what property.

CsvParser
    .mapTo(MyObject.class)
    .forEach(file, System.out::println);