Demystifying Java Iterator and Iterable: The Magician of Collection Traversal

Iterator and Iterable are two important interfaces for collection traversal in Java. The Iterator interface defines a next() method, which is used to return the next element in the collection, and a hasNext() method, which is used to check whether there is a next element in the collection. The Iterable interface defines an iterator() method, which is used to return an Iterator object. This Iterator object can be used to traverse the elements in the collection.

For collection traversal, we usually have two commonly used methods, one is the for-each loop, and the other is Iterator iterator traversal.

// 使用for-each循环遍历集合
List<String> list = new ArrayList<>();
list.add("A");
list.add("B");
list.add("C");

for (String s : list) {
System.out.println(s);
}

// 使用Iterator迭代器遍历集合
Iterator<String> iterator = list.iterator();
while (iterator.hasNext()) {
 System.out.println(iterator.next());
}

Both traversal methods have their own advantages and disadvantages. The for-each loop is more concise, but it cannot modify the elements in the collection, while the Iterator iterator traversal is more flexible, and it can modify the elements in the collection.

In actual development, these two traversal methods have practical application scenarios. When you only need to traverse the elements in the collection, you can directly use the for-each loop. When you need to modify the elements in the collection , you need to use an Iterator to traverse.

In addition to the two traversal methods introduced above, there are other ways to traverse collections in Java, such as using stream flow Programming to traverse.

In general, Iterator and Iterable are two very important interfaces in Java. They provide powerful support for collection traversal. By using Iterator or Iterable we can easily iterate over the elements in the collection.

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