在Java中列出 size() 方法和示例
Java中 List 接口的size()方法用于获取此列表中的元素个数。也就是说,此方法返回此列表容器中存在的元素的计数。
句法:
public int size()
参数:此方法不带任何参数。
返回值:此方法返回此列表中的元素数。
说明:假设它是一个整数列表
Input : {3,2,1,5,7}
Output : 5
示例 1:
Java
// Java program to Illustrate size() method
// of List class for Integer value
// Importing required classes
import java.util.*;
// Main class
public class GFG {
// Main driver method
public static void main(String[] arg)
{
// Creating object of ArrayList class
List list = new ArrayList();
// Populating List by adding integer elements
// using add() method
list.add(1);
list.add(2);
list.add(3);
list.add(4);
list.add(5);
// Printing elements of List
System.out.println("Before operation: " + list);
// Getting total size of list
// using size() method
int size = list.size();
// Printing the size of List
System.out.println("Size of list = " + size);
}
}
Java
// Java program to Illustrate size() method
// of List class for Integer value
// Importing required classes
import java.util.*;
// Main class
public class GFG {
// Main driver method
public static void main(String[] args)
{
// Creating an empty string list by
// declaring elements of string type
List list = new ArrayList();
// Populating List by adding string elements
// using add() method
list.add("Geeks");
list.add("for");
list.add("Geeks");
// Printing the List
System.out.println("Before operation: " + list);
// Getting total size of list
// using size() method
int size = list.size();
// Printing the size of list
System.out.println("Size of list = " + size);
}
}
输出
Before operation: [1, 2, 3, 4, 5]
Size of list = 5
示例 2:
Java
// Java program to Illustrate size() method
// of List class for Integer value
// Importing required classes
import java.util.*;
// Main class
public class GFG {
// Main driver method
public static void main(String[] args)
{
// Creating an empty string list by
// declaring elements of string type
List list = new ArrayList();
// Populating List by adding string elements
// using add() method
list.add("Geeks");
list.add("for");
list.add("Geeks");
// Printing the List
System.out.println("Before operation: " + list);
// Getting total size of list
// using size() method
int size = list.size();
// Printing the size of list
System.out.println("Size of list = " + size);
}
}
输出
Before operation: [Geeks, for, Geeks]
Size of list = 3