Article.java

package article;

public class Article {

  private int artikelID;
  private int artikelPreis;
  private int verkaufsmenge;

  public Article(int[] a) {
    this.artikelID = a[0];
    this.artikelPreis = a[1];
    this.verkaufsmenge = a[2];
  }

  public void printArticle() {
    System.out.println(this.artikelID + " " + this.artikelPreis + " " + this.verkaufsmenge);
  }

  public void printUmsatz() {
    System.out.println("Artikel-Nummer: " + this.artikelID + "\nUmsatz: " + (this.artikelPreis * this.verkaufsmenge) + "\n");
  }
}

Main.java

package article;

import java.io.FileNotFoundException;
import java.io.FileReader;
import java.util.ArrayList;
import java.io.BufferedReader;
import java.io.IOException;
import java.util.Arrays;
import java.util.ListIterator;

public class Main {
  static void readArticles(ArrayList<Article> arrayList, String file) {
    try {
      BufferedReader br = new BufferedReader(new FileReader(file));
      String str;
      
      while ((str = br.readLine()) != null) {
        if (!str.trim().isEmpty()) {
          //System.out.println(str.split("\\s+"));
          // Needs exactly a line like: [0-9]+ [0-9]+ [0-9]+
          arrayList.add(new Article(Arrays.stream(str.split("\\s+")).mapToInt(Integer::parseInt).toArray()));
        }
      }
      
      br.close();
    } catch (FileNotFoundException e) {
    } catch (IOException e) {
    }
  }

  static void printArticles(ArrayList<Article> arrayList) {
    ListIterator<Article> li = arrayList.listIterator();

    while (li.hasNext()) {
      li.next().printUmsatz();
    }
  }