Java ArrayList set()方法及实例

java.util.ArrayLis t 类的 set() 方法用于用指定的元素替换该列表中指定位置的元素。

语法

public E set(int index, E element)

参数： 该方法需要以下参数作为参数。

index- 要替换的元素的索引
element- 要存储在指定位置的元素

返回值： 该方法返回先前在指定位置的元素。

异常： 如果索引不在ArrayList的大小范围内，该方法会抛出 IndexOutOfBoundsException 。

下面是说明set()方法的例子。

例1 :

// Java program to demonstrate
// set() method
// for Integer value
  
import java.util.*;
  
public class GFG1 {
    public static void main(String[] argv) throws Exception
    {
        try {
  
            // Creating object of ArrayList<Integer>
            ArrayList<Integer>
                arrlist = new ArrayList<Integer>();
  
            // Populating arrlist1
            arrlist.add(1);
            arrlist.add(2);
            arrlist.add(3);
            arrlist.add(4);
            arrlist.add(5);
  
            // print arrlist
            System.out.println("Before operation: "
                               + arrlist);
  
            // Replacing element at the index 3 with 30
            // using method set()
            int i = arrlist.set(3, 30);
  
            // Print the modified arrlist
            System.out.println("After operation: "
                               + arrlist);
  
            // Print the Replaced element
            System.out.println("Replaced element: "
                               + i);
        }
  
        catch (IndexOutOfBoundsException e) {
            System.out.println("Exception thrown: "
                               + e);
        }
    }
}

输出。

Before operation : [1, 2, 3, 4, 5]
After operation : [1, 2, 3, 30, 5]
Replaced element : 4

例2： 对于IndexOutOfBoundsException

// Java program to demonstrate
// set() method
// for IndexOutOfBoundsException
  
import java.util.*;
  
public class GFG1 {
    public static void main(String[] argv) throws Exception
    {
        try {
  
            // Creating object of ArrayList<Integer>
            ArrayList<Integer>
                arrlist = new ArrayList<Integer>();
  
            // Populating arrlist1
            arrlist.add(1);
            arrlist.add(2);
            arrlist.add(3);
            arrlist.add(4);
            arrlist.add(5);
  
            // print arrlist
            System.out.println("Before operation : "
                               + arrlist);
  
            // Replacing element at the index 7 with 30
            // using method set()
            System.out.println("\nTrying to Replace"
                               + " the element at"
                               + " (index > Capacity) ");
            int i = arrlist.set(7, 30);
  
            // Print the modified arrlist
            System.out.println("After operation: "
                               + arrlist);
  
            // Print the Replaced element
            System.out.println("Replaced element: "
                               + i);
        }
  
        catch (IndexOutOfBoundsException e) {
            System.out.println("Exception thrown : " + e);
        }
    }
}

输出。

Before operation : [1, 2, 3, 4, 5]

Trying to Replace the element at (index > Capacity) 
Exception thrown : java.lang.IndexOutOfBoundsException: Index: 7, Size: 5