如何在Java中获取集合的大小?
给定Java中的 Collection ,任务是找到集合的长度或大小。
例子:
Input: Array_List: [1, 2, 3,4]
Output: 4
Input: Linked_List: [geeks, for, geeks]
Output: 3
可以使用size()方法找到不同集合的大小。此方法返回此集合中的元素数。此方法不带任何参数。
下面是实现:
示例 1:
Java
// Java program to demonstrate
// size() method of collection
import java.util.*;
public class Example1 {
public static void main(String[] args)
{
// Creating object of List
List Array_List = new ArrayList();
// add elements
Array_List.add(1);
Array_List.add(2);
Array_List.add(3);
Array_List.add(3);
// getting total size of list
// using size() method
int size = Array_List.size();
// print the size of list
System.out.println("Size of list = " + size);
// print list
System.out.println("Array_List = " + Array_List);
}
}
Java
// Java program to demonstrate
// size() method of Collection
import java.util.*;
import java.io.*;
class Example2 {
public static void main(String[] args)
{
// Creating object of LinkedList
LinkedList al = new LinkedList();
// Populating LinkedList
al.add("GEEKS");
al.add("FOR");
al.add("GEEKS");
// getting total size of Linkedlist
// using size() method
int size = al.size();
// print the size
System.out.println("Size of the linkedlist = "
+ size);
// print Linkedlist
System.out.println("Linkedlist = " + al);
}
}
输出
Size of list = 4
Array_List = [1, 2, 3, 3]
示例 2:
Java
// Java program to demonstrate
// size() method of Collection
import java.util.*;
import java.io.*;
class Example2 {
public static void main(String[] args)
{
// Creating object of LinkedList
LinkedList al = new LinkedList();
// Populating LinkedList
al.add("GEEKS");
al.add("FOR");
al.add("GEEKS");
// getting total size of Linkedlist
// using size() method
int size = al.size();
// print the size
System.out.println("Size of the linkedlist = "
+ size);
// print Linkedlist
System.out.println("Linkedlist = " + al);
}
}
输出
Size of the linkedlist = 3
Linkedlist = [GEEKS, FOR, GEEKS]