Java中的AbstractList迭代器（iterator()）方法及示例

java.util.AbstractList 类的 iterator() 方法用于以正确的顺序返回此列表中的元素的迭代器。

该实现返回迭代器接口的直接实现，依赖于支持列表的size()，get(int)和remove(int)方法。

语法：

public Iterator iterator()

返回值： 此方法以正确的顺序返回此列表中的元素的迭代器。

以下是用于说明iterator()方法的示例。

示例1：

// Java program to demonstrate
// iterator() method
// for Integer value
  
import java.util.*;
  
public class GFG1 {
    public static void main(String[] argv)
        throws Exception
    {
  
        try {
  
            // Creating object of AbstractList<Integer>
            AbstractList<Integer>
                arrlist1 = new ArrayList<Integer>();
  
            // Populating arrlist1
            arrlist1.add(10);
            arrlist1.add(20);
            arrlist1.add(30);
            arrlist1.add(40);
            arrlist1.add(50);
  
            // print arrlist1
            System.out.println("ArrayList : "
                               + arrlist1);
  
            // creating object of Iterator
            // using iterator() method
            Iterator it = arrlist1.iterator();
  
            // printing the iterated value
            while (it.hasNext()) {
                System.out.println("Value is : "
                                   + it.next());
            }
        }
  
        catch (NullPointerException e) {
            System.out.println("Exception thrown : " + e);
        }
    }
}

ArrayList：[10，20，30，40，50]
Value is: 10
Value is: 20
Value is: 30
Value is: 40
Value is: 50

示例2：

// Java program to demonstrate
// iterator() method
// for String value
  
import java.util.*;
  
public class GFG1 {
    public static void main(String[] argv)
        throws Exception
    {
  
        try {
  
            // Creating object of AbstractList<String>
            AbstractList<String>
                arrlist1 = new ArrayList<String>();
  
            // Populating arrlist1
            arrlist1.add("A");
            arrlist1.add("B");
            arrlist1.add("C");
            arrlist1.add("D");
            arrlist1.add("E");
  
            // print arrlist1
            System.out.println("ArrayList : "
                               + arrlist1);
  
            // creating object of Iterator
            // using iterator() method
            Iterator it = arrlist1.iterator();
  
            // printing the iterated value
            while (it.hasNext()) {
                System.out.println("Value is : "
                                   + it.next());
            }
        }
  
        catch (NullPointerException e) {
            System.out.println("Exception thrown : " + e);
        }
    }
}

ArrayList：[A，B，C，D，E]
Value is: A
Value is: B
Value is: C
Value is: D
Value is: E