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 = it.next();
    }
    Map map = new HashMap();
    // For keys of a map
    for (Iterator it = map.keySet().iterator(); it.hasNext();) {
      Object key = it.next();
    }

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

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

Related examples in the same category

1.	De-mystify the Iterator interface, showing how to write a simple Iterator for an Array of Objects
2.	Iterate over Set
3.	Demonstrate iterators.
4.	Use the for-each for loop to cycle through a collection.
5.	List Iterator
6.	Iterate a Collection and remove an item (Exception, wrong version)
7.	Use an Iterator and remove the item with Iterator.remove()
8.	An Iterator wrapper for an Enumeration.
9.	EmptyIterator is an iterator which is empty.
10.	Implements an java.util.Iterator over any array
11.	Treat an Iterator as an Iterable
12.	Iterator class for sparse values in an array.
13.	Iterator class for values contained in an array range.
14.	Array Iterator
15.	Cyclic Iteration
16.	Create singleton Iterator
17.	Empty Iterator
18.	An Iterator that wraps a number of Iterators
19.	An Iterator to iterate over the elements of an array
20.	Sorted Iterator
21.	Iterator Union of Iterators
22.	Iterator Utils
23.	Linked Iterator
24.	Prefetch Iterator
25.	Protects an given iterator by preventing calls to remove().
26.	An Iterator that returns the elements of a specified array, or other iterators etc.
27.	An Iterator wrapper for an Object[], allow us to deal with all array like structures in a consistent manner.
28.	An array iterator
29.	Adapt iterator to iterable
30.	Static utility methods, classes, and abstract classes for iteration.
31.	Iterator Collection
32.	Convert Iterable to List
33.	A singleton null object Iterator implementation.

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

Related examples in the same category