Java中的 AbstractList set() 方法及示例

Java.util.AbstractList类的set()方法用于将使用 AbstractList 类创建的抽象列表中的任何特定元素替换为另一个元素。这可以通过在 set() 方法的参数中指定要替换的元素的位置和新元素来完成。

句法：

AbstractList.set(int index, Object element)

参数：此函数接受两个参数，如下所述：

• index ：这是整数类型，指的是要从抽象列表中替换的元素的位置。
• element ：它将替换现有元素的新元素，并且与抽象列表具有相同的对象类型。

返回值：该方法从抽象列表中返回被新值替换的前一个值。

下面的程序说明了 AbstractList.set() 方法：

// Java code to illustrate set()
  
import java.util.*;
import java.util.LinkedList;
  
public class AbstractListDemo {
    public static void main(String args[])
    {
  
        // Creating an empty AbstractList
        AbstractList list = new LinkedList();
  
        // Use add() method to add elements in the list
        list.add("Geeks");
        list.add("for");
        list.add("Geeks");
        list.add("10");
        list.add("20");
  
        // Displaying the AbstractList
        System.out.println("AbstractList:" + list);
  
        // Using set() method to replace Geeks with GFG
        System.out.println("The Object that is replaced is: "
                           + list.set(2, "GFG"));
  
        // Using set() method to replace 20 with 50
        System.out.println("The Object that is replaced is: "
                           + list.set(4, "50"));
  
        // Displaying the modified AbstractList
        System.out.println("The new AbstractList is:" + list);
    }
}

输出：

AbstractList:[Geeks, for, Geeks, 10, 20]
The Object that is replaced is: Geeks
The Object that is replaced is: 20
The new AbstractList is:[Geeks, for, GFG, 10, 50]

方案二：

// Java code to illustrate set()
  
import java.util.*;
  
public class LinkedListDemo {
    public static void main(String args[])
    {
  
        // Creating an empty AbstractList
        AbstractList
            list = new LinkedList();
  
        // Use add() method to add elements in the list
        list.add(10);
        list.add(20);
        list.add(30);
        list.add(40);
        list.add(50);
  
        // Displaying the AbstractList
        System.out.println("AbstractList:" + list);
  
        // Using set() method to replace 10 with 100
        System.out.println("The Object that is replaced is: "
                           + list.set(0, 100));
  
        // Using set() method to replace 20 with 200
        System.out.println("The Object that is replaced is: "
                           + list.set(1, 200));
  
        // Displaying the modified AbstractList
        System.out.println("The new AbstractList is:" + list);
    }
}

输出：

AbstractList:[10, 20, 30, 40, 50]
The Object that is replaced is: 10
The Object that is replaced is: 20
The new AbstractList is:[100, 200, 30, 40, 50]