How Does Enhanced For Loop Plant Inwards Java?

It's a long fourth dimension since JDK 1.5 introduced the enhanced for loop, almost 12 years agone inwards the yr 2004, but yet many Java developers don't know basics of enhanced for loop, likewise known every bit for each loop inwards Java. The enhanced for loop provides the cleanest agency to loop through an array or collection inwards Java, every bit you lot don't postulate to give-up the ghost on rail of counter or you lot don't postulate to telephone phone the hasNext() method to banking concern agree whether at that spot are to a greater extent than elements left. The key point, which many Java developer doesn't know virtually the enhanced for loop is that you lot tin usage whatsoever Object which implements the Iterable interface on for (: ) construct, you lot tin fifty-fifty usage enhanced for loop to loop through the array. Since JDK 8 likewise introduced a forEach() constituent to render looping functionality, don't confuse when I tell for each loop alongside that. In this article, we'll come across how enhanced for loop plant too twain of of import points related to it.

Btw, Java v introduced several useful features along alongside enhanced for loop e.g. Generics, Enum, Concurrency API, Variable arguments, Static import, covariant method overriding etc. Nowadays, it's expected from a Java developer to know all these features past times heart. If you lot experience you lot lack inwards whatsoever of these thus I propose reading Cay S. Horstmann's Core Java for the Impatient book. One of the best mass to fill upward your gap inwards Java. It likewise covers Java SE 8.

How enhanced for loop plant inwards Java

Suppose, you lot desire to loop over a List inwards Java, you lot tin write next code to achieve that using the enhanced for loop:

List<String> listOfCities = new ArrayList<>(Arrays.asList(new String[]{"USD", "GBP", "INR"}));  for(String metropolis : listOfCities){    System.out.println(city); }

This is equivalent to the next code because enhanced for loop is nix but a syntactic saccharide over Iterator inwards Java:

for (Iterator<String> i = listOfCities.iterator(); i.hasNext();) {    String metropolis = i.next();    System.out.println(city); }

Of course, enhanced for loop approach is much cleaner too readable but it is likewise to a greater extent than express every bit you lot cannot take away elements spell iterating, at that spot is no reference to the iterator to telephone phone the remove() method, too if you lot telephone phone remove() method of List thus you lot volition cease upward alongside ConcurrentModificationException inwards Java. To avoid this dreaded mistake come across this article.

Even though enhanced for loop internally uses an Iterator, it doesn't divulge the reference to exterior world.

Both spell too for inwards combination alongside ListIterator too Iterator gives to a greater extent than flexibility too ability every bit you lot tin iterate both frontwards too backward, but yep for other Collection e.g. a Set or a Queue which doesn't back upward ListIterator, enhanced for loop is same every bit using Iterator alongside for or spell loop.

hither is a overnice summary of why enhanced for loop was introduced inwards Java v too why you lot should usage it, along alongside syntax too instance of how to usage it for iterating over collection too array.

That's all virtually how enhanced for loop plant inwards Java. I am certain you lot convey been using enhanced for loop oft but you lot should know that you lot tin usage whatsoever object which implements Iterable here. Even your custom object tin hold upward used hither if it implements java.util.Iterator interface. Enhanced for loop of JDK v is best for read-only iteration i.e. you lot but desire to access, read or impress information but it's non suitable if you lot desire to take away elements during traversal, for that usage Iterator alongside either for or while loop inwards Java. To larn to a greater extent than virtually enhanced for loop too other Java v features, read Core Java For Impatient.

Further Learning
Complete Java Masterclass
Java Fundamentals: The Java Language
Java In-Depth: Become a Complete Java Engineer!

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