Java ArrayList从指定的索引中删除元素

java.util.ArrayList类中的remove(int index)方法会移除该列表中指定位置的元素，并将任何后续元素向左移动（即从其索引中减一）。

语法:

public removed_element remove(int index)

参数: 要删除的元素的索引。

返回值: 该方法返回从列表中删除的元素。

异常: 如果索引超出范围，该方法会抛出IndexOutOfBoundsException。

// Java program to remove an element
// from an specified index from
// an ArrayList.
  
import java.util.ArrayList;
  
public class GFG {
    public static void main(String[] arg)
    {
  
        // creating an empty ArrayList with an initial
        // capacity of 5
        ArrayList<String> flower = new ArrayList<String>(5);
  
        // using add() method to add elements in the
        // ArrayList flower
        flower.add("red-rose");
        flower.add("tulip");
        flower.add("sun-flower");
        flower.add("marie-gold");
        flower.add("orchid");
  
        // printing the size of the ArrayList flower
        System.out.println("Size of list: "
                           + flower.size());
  
        // printing the ArrayList flower
        System.out.println("Flower ArrayList = " + flower);
  
        // Removing element at 3rd position from ArrayList
        // flower
        System.out.println(
            "Removing element at index = 2 ");
        flower.remove(2);
  
        System.out.println("After removing element");
  
        // printing the size of the ArrayList flower
        System.out.println("Size of list: "
                           + flower.size());
  
        // printing the ArrayList flower
        System.out.println("Flower ArrayList = " + flower);
    }
}

输出

Size of list: 5
Flower ArrayList = [red-rose, tulip, sun-flower, marie-gold, orchid]
Removing element at index = 2 
After removing element
Size of list: 4
Flower ArrayList = [red-rose, tulip, marie-gold, orchid]

当我们试图删除一个索引大于或等于数组列表大小的元素时，编辑器会在运行时给我们一个**索引超出范围的异常。

// Java program to show the exception
// of remove() method
  
import java.util.ArrayList;
  
public class ArrayListDemo {
   public static void main(String[] args) {
        
      // create an empty array list with an initial capacity
      ArrayList<Integer> arrlist = new ArrayList<Integer>(5);
  
      // use add() method to add elements in the deque
      arrlist.add(20);
      arrlist.add(15);
      arrlist.add(30);
      arrlist.add(45);
  
      System.out.println("Size of list: " + arrlist.size());
        
      // let us print all the elements available in list
      for (Integer number : arrlist) {
         System.out.println("Number = " + number);
      }  
        
      // Removes element at 5th position
      // which is not present in the list
      // and will therefore give IndexOutOfBound exception
      arrlist.remove(4);
  
      System.out.println("Now, Size of list: " + arrlist.size());
        
      // let us print all the elements available in list
      for (Integer number : arrlist) {
         System.out.println("Number = " + number);
      }
   }
}

Exception in thread "main" java.lang.IndexOutOfBoundsException: Index 4 out of bounds for length 4