获取集合大小并验证集合为空的Java程序
这 尺寸() Java.util.Collection 接口的isEmpty()用于检查集合的大小以及集合是否为空。 isEmpty()方法不接受任何参数,也不返回任何值。
例子:
Input:[99, 54, 112, 184, 2]
Output:size = 5 and Collection is not empty
Input:[]
Output: size = 0 and Collection is empty
大小()方法:
句法:
public int size()
参数:此方法不接受任何参数。
返回值:此方法返回此列表中的元素数。
isEmpty() 方法:
句法:
Collection.isEmpty()
参数:该方法不接受任何参数
返回值:此方法不返回任何值。
示例 1:使用 LinkedList 类
Java
//Java Program to Get the Size of Collection
// and Verify that Collection is Empty
// using LinkedList class
import java.io.*;
import java.util.*;
class GFG {
public static void main (String[] args) {
Collection list = new LinkedList();
//add integer values in this list
list.add(99);
list.add(54);
list.add(112);
list.add(184);
list.add(2);
// Output the present list
System.out.print("The elements in Collection : ");
System.out.println(list);
//returns the size of the list
System.out.println("Size of the collection "+list.size());
// Check if list is empty using isEmpty() method
System.out.println("Is the LinkedList empty: "
+ list.isEmpty());
// Clearing the LinkedList
list.clear();
// printing the new list
System.out.println("The new List is: " + list);
// Check if list is empty
// using isEmpty() method
System.out.println("Is the LinkedList empty: "
+ list.isEmpty());
}
}
Java
//Java Program to Get the Size of Collection and
// Verify that Collection is Empty
// using ArrayList class
import java.io.*;
import java.util.*;
class GFG {
public static void main (String[] args) {
Collection arraylist = new ArrayList();
arraylist.add("Geeks");
arraylist.add("for");
arraylist.add("geeks");
// returns the size of the arraylist
System.out.println("Size of the collection "+arraylist.size());
// Check if list is empty using isEmpty() method
System.out.println("Is the ArrayList empty: "
+ arraylist.isEmpty());
}
}
输出
The elements in Collection : [99, 54, 112, 184, 2]
Size of the collection 5
Is the LinkedList empty: false
The new List is: []
Is the LinkedList empty: true
示例 2:使用 ArrayList 类
Java
//Java Program to Get the Size of Collection and
// Verify that Collection is Empty
// using ArrayList class
import java.io.*;
import java.util.*;
class GFG {
public static void main (String[] args) {
Collection arraylist = new ArrayList();
arraylist.add("Geeks");
arraylist.add("for");
arraylist.add("geeks");
// returns the size of the arraylist
System.out.println("Size of the collection "+arraylist.size());
// Check if list is empty using isEmpty() method
System.out.println("Is the ArrayList empty: "
+ arraylist.isEmpty());
}
}
输出
Size of the collection 3
Is the ArrayList empty: false