Java中的 ArrayList size() 方法及示例

Java.util.ArrayList类的size()方法用于获取此列表中元素的数量。

句法：

public int size()

返回值：此方法返回此列表中的元素数。

以下是说明 size() 方法的示例。

示例 1：

// Java program to demonstrate
// size() method
// for Integer value
  
import java.util.*;
  
public class GFG1 {
    public static void main(String[] argv)
        throws Exception
    {
        try {
  
            // Creating object of ArrayList
            ArrayList
                arrlist = new ArrayList();
  
            // 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);
  
            // getting total size of arrlist
            // using size() method
            int size = arrlist.size();
  
            // print the size of arrlist
            System.out.println("Size of list = "
                               + size);
        }
  
        catch (IndexOutOfBoundsException e) {
  
            System.out.println("Exception thrown: "
                               + e);
        }
    }
}

输出：

Before operation: [1, 2, 3, 4, 5]
Size of list = 5

示例 2：

// Java program to demonstrate
// size() method
// for String value
  
import java.util.*;
  
public class GFG1 {
    public static void main(String[] argv)
        throws Exception
    {
        try {
  
            // Creating object of ArrayList
            ArrayList
                arrlist = new ArrayList();
  
            // Populating arrlist1
            arrlist.add("A");
            arrlist.add("B");
            arrlist.add("C");
  
            // print arrlist
            System.out.println("Before operation: "
                               + arrlist);
  
            // getting total size of arrlist
            // using size() method
            int size = arrlist.size();
  
            // print the size of arrlist
            System.out.println("Size of list = "
                               + size);
        }
  
        catch (IndexOutOfBoundsException e) {
  
            System.out.println("Exception thrown: "
                               + e);
        }
    }
}

输出：

Before operation: [A, B, C]
Size of list = 3