read-and-parse-csv.java

package practice;

import java.io.BufferedReader;
import java.io.InputStreamReader;
import java.nio.file.Files;
import java.nio.file.Paths;
import java.nio.file.StandardOpenOption;
import java.util.HashMap;
import java.util.Map;

class Result {
	static private int totalLines = 0;
	static private Map<String, SaleRecord> allsales = new HashMap<>();
	
	static class SaleRecord {
		private int unitsSold = 0;
		private int maxBrandCount = 0;
		private String maxBrand;
		private Map<String, Integer> brandCount = new HashMap<>();
		
		public SaleRecord(int qtySold, String brand) {
			this.add(qtySold);
			this.addBrand(brand);
		}

		public void add(int qty) {
			this.unitsSold += qty;
		}
		
		public void addBrand(String brand) {
			Integer s = brandCount.get(brand);
			if (s == null) {
				brandCount.put(brand, Integer.valueOf(1));
				if (1 > maxBrandCount) {
					maxBrandCount = 1;
					maxBrand = brand;
				}
			} else {
				int temp = s + 1;
				if (temp > maxBrandCount) {
					maxBrandCount = temp;
					maxBrand = brand;
				}
				brandCount.put(brand, Integer.valueOf(temp));
			}
		}
		
		public String getMaxBrand() {
			return this.maxBrand;
		}
		
		public int getUnitsSold() {
			return this.unitsSold;
		}
	}

    public static void generateFiles(String filename) throws Exception {
    	Files.lines(Paths.get(filename)).forEach(Result::ProcessLine);
    	
    	String[] out0 = new String[1];
    	String[] out1 = new String[1];
    	allsales.forEach((product, sr) -> {
    		out0[0] += product + "," + ((double)sr.getUnitsSold() / (double)totalLines) + "\n";
    		out1[0] += product + "," + sr.getMaxBrand() + "\n";
    	});
    	
    	String _filename = filename.substring(0,filename.length()-4);
    	Files.write(Paths.get(_filename+"_0.csv"), out0[0].getBytes(), StandardOpenOption.CREATE);
    	Files.write(Paths.get(_filename+"_1.csv"), out1[0].getBytes(), StandardOpenOption.CREATE);
    }
    
    static private void ProcessLine(String line) {
    	totalLines += 1;
		String[] tokens = line.split(",");

		String product = tokens[2];
		String brand = tokens[4];
		int qtySold = Integer.parseInt(tokens[3]);

		SaleRecord sr = allsales.get(product);
		if (sr == null) {
			allsales.put(product, new SaleRecord(qtySold, brand));
		} else {
			sr.add(qtySold);
			sr.addBrand(brand);
			allsales.put(product, sr);
		}
    }
}

public class ReadAndParseCSV {

	public static void main(String[] args) throws Exception {
        BufferedReader bufferedReader = new BufferedReader(new InputStreamReader(System.in));
        String input_file;

		input_file = bufferedReader.readLine();
		Result.generateFiles(input_file);
		bufferedReader.close();
	}
}