Making Your Objects Iterable - Java Collection Framework

Java examples for Collection Framework:Iterable

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Introduction

Extend the Iterable<T> interface.

Implement the iterator() method to return the Iterator<T> object from this collection.

Demo Code


import java.util.HashMap;
import java.util.Iterator;
import java.util.List;
import java.util.Map;

public class Main implements Iterable<Stock> {

  Map<String, Stock> portfolio = new HashMap<>();

  public void add(Stock stock) {
    portfolio.put(stock.getSymbol(), stock);
  }//w  w  w . ja  v a 2 s.  co m

  public void add(List<Stock> stocks) {
    for (Stock s : stocks) {
      portfolio.put(s.getSymbol(), s);
    }
  }

  @Override
  public Iterator<Stock> iterator() {
    return portfolio.values().iterator();
  }

  public static void main(String[] args) {
    Main myPortfolio = new Main();
    myPortfolio.add(new Stock("ORCL", "Oracle", 5010.0));
    myPortfolio.add(new Stock("AAPL", "Apple", 2010.0));
    myPortfolio.add(new Stock("GOOG", "Google", 1100.0));
    myPortfolio.add(new Stock("IBM", "IBM", 510.0));
    myPortfolio.add(new Stock("MCD", "McDonalds", 3010.0));

    System.out.println("legacy for-each loop");
    for (Stock stock : myPortfolio) {
      System.out.println(stock);
    }

    System.out.println("using Java 8 foreach implementation");
    myPortfolio.forEach(s -> System.out.println(s));
  }
}

class UnmodifiableIterator {
  public static <E> Iterator<E> wrap(final Iterator<E> iter) {
    return new Iterator<E>() {

      @Override
      public boolean hasNext() {
        return iter.hasNext();
      }

      @Override
      public E next() {
        return iter.next();
      }

      @Override
      public void remove() {
        throw new UnsupportedOperationException("Remove not supported.");
      }
    };
  }
}

class Stock {
  private String symbol;
  private String name;
  private double shares;

  public Stock(String symbol, String name, double shares) {
    this.symbol = symbol;
    this.name = name;
    this.shares = shares;
  }

  public String getSymbol() {
    return symbol;
  }

  public String getName() {
    return name;
  }

  public double getShares() {
    return shares;
  }

  public String toString() {
    return shares + " shares of " + symbol + " (" + name + ")";
  }
}

Result


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