Java中的 ArrayList iterator() 方法及示例

Java Collection Framework中ArrayList 类的iterator()方法用于按正确顺序获取此列表中元素的迭代器。返回的迭代器是快速失败的。

句法：

Iterator iterator()

参数：此方法不接受任何参数。

返回值：此方法以正确的顺序返回此列表中元素的迭代器

下面的示例说明了 ArrayList.iterator() 方法：

方案一：

// Java code to illustrate iterator()
  
import java.util.*;
  
public class GFG {
  
    public static void main(String[] args)
    {
        // Create and populate the list
        ArrayList list
            = new ArrayList<>();
  
        list.add("Geeks");
        list.add("for");
        list.add("Geeks");
        list.add("is");
        list.add("a");
        list.add("CS");
        list.add("Students");
        list.add("Portal");
  
        // Displaying the list
        System.out.println("The list is: \n"
                           + list);
  
        // Create an iterator for the list
        // using iterator() method
        Iterator iter
            = list.iterator();
  
        // Displaying the values after iterating
        // through the list
        System.out.println("\nThe iterator values"
                           + " of list are: ");
        while (iter.hasNext()) {
            System.out.print(iter.next() + " ");
        }
    }
}

输出：

The list is: 
[Geeks, for, Geeks, is, a, CS, Students, Portal]

The iterator values of list are: 
Geeks for Geeks is a CS Students Portal

方案二：

// Java code to illustrate iterator()
  
import java.util.*;
  
public class GFG {
  
    public static void main(String args[])
    {
        // Creating an empty ArrayList
        ArrayList list
            = new ArrayList();
  
        // Use add() method to add
        // elements into the list
        list.add(10);
        list.add(15);
        list.add(30);
        list.add(20);
        list.add(5);
  
        // Displaying the list
        System.out.println("The list is: \n"
                           + list);
  
        // Create an iterator for the list
        // using iterator() method
        Iterator iter = list.iterator();
  
        // Displaying the values
        // after iterating through the list
        System.out.println("\nThe iterator values"
                           + " of list are: ");
        while (iter.hasNext()) {
            System.out.print(iter.next() + " ");
        }
    }
}

输出：

The list is: 
[10, 15, 30, 20, 5]

The iterator values of list are: 
10 15 30 20 5