for (Iterator<String> itr = birds.iterator(); itr.hasNext();) { String bird = itr.next(); } 从性能角度来看,这种方式还好,获取每个元素都是固定时间,但是,从代码风格来看,略显复杂了。 不过,iterator有个优点,就是可以在循环体内删除列表中的元素(可能成功-依赖List的具体实现),而其他的2种方式不行。
Java的三种循环：foreach，Iterator和classicforloop 不得不说，java语⾔在提供了这三种循环⽅式带来灵活性的同时，同时也将⼀些“混乱”引⼊了进来。这⾥的“混乱”并不是真正意义上的混乱，⽽是由于没有统⼀的风格⽽带来使⽤习惯的问题——想象⼀下，如果同⼀个项⽬中这三种都有⼈⽤，...
InJava 8, with the introduction ofFunctional InterfaceΛ’s, Java architects have provided us with an Internal Iterator (forEach loop) supported byCollection frameworkand can be used with the collections object. This method performs a given action for each element of the collection. Let’s see ...
import java.util.Iterator; /** * Instances of classes that implement this interface can * be used with the enhanced for loop. * @since 1.5 */ public interface Iterable<T> { /** * Returns an {@link Iterator} for the elements in * this object. * @return An {@code Iterator} instance...
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Iterator 是一个集合上的迭代器,用来替代 Enumeration 进行遍历、迭代。 它和Enumeration 有什么不同呢? 根据官方文档: Iterators differ from enumerations in two ways: Iterators allow the caller to remove elements from the underlying collection during the iteration with well-defined semantics. ...
普通fori 循环 普通for 循环原理很简单,首先获取集合的长度userList.size(),循环体内根据循环到的下标获取对应的元素, 然后每次循环+1,达到遍历整个集合的目的。 这种写法在以前非常的常见,现在大多使用forEach替代。 代码语言:javascript 代码运行次数:0
iterator(); while(it.hasNext()) { Integer i = it.next(); if(i < 10) { it.remove(); } } System.out.println(numbers); } } Try it Yourself » Note: Trying to remove items using a for loop or a for-each loop would not work correctly because the collection is changing size ...
Java 中的“While-loop” | C# 中的“For 循环” | Python 中的“For-loop” | | --- | --- | --- | | //让我们初始化一个变量 int I = 3;而(i > 0) {System.out.println("三个 hello ");-我;} | //这是一个迷人的循环for(int I = 0;我<3;i++){控制台。WriteLine(“你好!
Example: Implementation of Iterator In the example below, we have implemented thehasNext(),next(),remove()andforEachRemining()methods of theIteratorinterface in anArrayList. importjava.util.ArrayList;importjava.util.Iterator;classMain{publicstaticvoidmain(String[] args){// Creating an ArrayListArrayL...