Item 58: Prefer for-each loops to traditional for loops

58. For-each loops should be selected over traditional for loops

• The conventional for statement has more to describe, and the probability of making a mistake increases.
• You can use for-each even when there are nested iterations.

package tryAny.effectiveJava;

import java.util.Arrays;
import java.util.Collection;

public class NestedFor {
    enum Suit {
        CLUB, DIAMOND, HEART, SPADE
    };

    enum Rank {
        ACE, DEUCE, THREE, FOUR, FIVE, SIX, SEVEN, EIGHT, NINE, TEN, JACK, QUEEN, KING
    };

    public static void main(String[] args) {
        Collection<Suit> suits = Arrays.asList(Suit.values());
        Collection<Rank> ranks = Arrays.asList(Rank.values());

        for (Suit suit : suits) {
            for (Rank rank : ranks) {
                System.out.println("Handle" + suit + ":number" + rank);
            }
        }
    }
}

• Generally, there are three situations where for-each cannot be used.

• When filtering to remove specific elements

• When converting element values

• When scanning multiple element sets in parallel

• You can retrieve elements with for-each for objects that implement Iterable.