Listing the Elements of a Collection : Iterator « Collections Data Structure « Java

Listing the Elements of a Collection


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

public class Main {
  public static void main(String[] argv) {
    List collection = new ArrayList();

    // For a set or list
    for (Iterator it = collection.iterator(); it.hasNext();) {
      Object element =;
    Map map = new HashMap();
    // For keys of a map
    for (Iterator it = map.keySet().iterator(); it.hasNext();) {
      Object key =;

    // For values of a map
    for (Iterator it = map.values().iterator(); it.hasNext();) {
      Object value =;

    // For both the keys and values of a map
    for (Iterator it = map.entrySet().iterator(); it.hasNext();) {
      Map.Entry entry = (Map.Entry);
      Object key = entry.getKey();
      Object value = entry.getValue();


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