Reading a CSV File with Arbitrary Number of Columns

Deepika Sahu answered on December 30, 2022 Popularity 1/10 Helpfulness 1/10

answer Reading a CSV File with Arbitrary Number of Columns

Reading a CSV File with Arbitrary Number of Columns

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import java.io.FileReader;
import java.io.IOException;
import java.util.List;

import org.supercsv.cellprocessor.Optional;
import org.supercsv.cellprocessor.ParseInt;
import org.supercsv.cellprocessor.ParseLong;
import org.supercsv.cellprocessor.constraint.NotNull;
import org.supercsv.cellprocessor.constraint.StrRegEx;
import org.supercsv.cellprocessor.ift.CellProcessor;
import org.supercsv.io.CsvListReader;
import org.supercsv.io.ICsvListReader;
import org.supercsv.prefs.CsvPreference;

public class ReadCSVFileWithArbitraryNumberOfColumns {

	static final String CSV_FILENAME = "data.csv";

	public static void main(String[] args) throws IOException
	{
		try(ICsvListReader listReader = new CsvListReader(new FileReader(CSV_FILENAME), CsvPreference.STANDARD_PREFERENCE))
		{
			//First Column is header names- though we don't need it in runtime
			@SuppressWarnings("unused")
			final String[] headers = listReader.getHeader(true);
			CellProcessor[] processors = null;

			List&lt;String&gt; fieldsInCurrentRow;
			while ((fieldsInCurrentRow = listReader.read()) != null) {
				if(fieldsInCurrentRow.size() == 5){
					processors = getFiveColumnProcessors();
				}else if(fieldsInCurrentRow.size() == 4) {
					processors = getFourColumnProcessors();
				}else if(fieldsInCurrentRow.size() == 3) {
					processors = getThreeColumnProcessors();
				}else{
					//Create more processors
				}
				final List&lt;Object&gt; formattedFields = listReader.executeProcessors(processors);
				System.out.println(String.format("rowNo=%s, customerList=%s", listReader.getRowNumber(), formattedFields));
			}
		}
	}

	private static CellProcessor[] getFiveColumnProcessors() {
		final String emailRegex = "[a-z0-9\\._]+@[a-z0-9\\.]+";
		StrRegEx.registerMessage(emailRegex, "must be a valid email address");

		final CellProcessor[] processors = new CellProcessor[] {
				new NotNull(new ParseInt()), // CustomerId
				new NotNull(), // CustomerName
				new NotNull(), // Country
				new Optional(new ParseLong()), // PinCode
				new StrRegEx(emailRegex) // Email
		};
		return processors;
	}
	private static CellProcessor[] getFourColumnProcessors() {
		final CellProcessor[] processors = new CellProcessor[] {
				new NotNull(new ParseInt()), // CustomerId
				new NotNull(), // CustomerName
				new NotNull(), // Country
				new Optional(new ParseLong()) // PinCode
		};
		return processors;
	}
	private static CellProcessor[] getThreeColumnProcessors() {
		final CellProcessor[] processors = new CellProcessor[] {
				new NotNull(new ParseInt()), // CustomerId
				new NotNull(), // CustomerName
				new NotNull() //Country
		};
		return processors;
	}
}

Popularity 1/10 Helpfulness 1/10 Language java

Source: howtodoinjava.com

Tags: csv file java

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Contributed on Dec 30 2022

Deepika Sahu

0 Answers Avg Quality 2/10

Reading a CSV File with Arbitrary Number of Columns

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