How to use foreach loop (enhanced for) that came with Java 5?

This short examples explain everything:

package com.farenda.solved;

import java.util.Arrays;
import java.util.Collections;
import java.util.List;

public class JavaSolved {

    private static int[] numbers = { 1, 2, 3 };
    private static List<String> objects
        = Arrays.asList(new String[] {"a", "b", "c"});
    private static List emptyList = Collections.emptyList();

    public static void main(String[] args) {
        // With arrays it uses "index" and array's length field to iterate:
        System.out.println("Iterating array: " + numbers);
        for (int x : numbers) {
            System.out.println(x);
        }

        // It works with any class implementing java.lang.Iterable,
        // so Lists, Sets, Maps, etc.
        // Underneath it uses an iterator:
        System.out.println("Iterating over Iterable: " + objects);
        for (String s : objects) {
            System.out.println(s);
        }

        // When Iterable or array is empty Java for-each daos nothing:
        System.out.println("Iterating over an empty Iterable: " + emptyList);
        for (Object o : emptyList) {
            System.out.println(o);
        }

        // For-each doesn't check if Array or Iterable is null and will
        // throw NullPointerException when given one!
    }
}

Using Java for-each loop doesn’t work when you want to modify (e.g. remove matching element) Iterable over which you are iterating. In such case you will need to use simple iterator.

Let’s compile and run the examples:

$> javac src/com/farenda/solved/*.java -d out
$> java -cp out com.farenda.solved.JavaSolved
Iterating array: [I@659e0bfd
1
2
3
Iterating over Iterable: [a, b, c]
a
b
c
Iterating over an empty Iterable: []