ConcurrentSkipListSet的lower()方法用於返回此集合中存在的最大元素,該元素嚴格小於指定元素。如果集合中不存在此類元素,則此函數將返回null。
用法:
public E lower (E e)
參數:此方法僅采用一個參數,e是要匹配的指定值。
返回值:此方法返回的值是集合中存在的最大元素,該值嚴格小於指定元素。如果不存在此類元素,則它將返回Null。
異常:此方法引發以下異常:
- ClassCastException:如果此集合的元素的類與指定的集合不兼容,則拋出此錯誤。
- NullPointerException :如果指定的集合為null,則拋出此錯誤。
以下示例程序旨在說明ConcurrentSkipListSet類的lower()函數:
示例1:在下麵的程序中,指定的元素為67,我們的集合也包含元素67,但是由於lower()方法返回的值嚴格較少,因此未返回該元素。
// Java program to demonstrate
// ConcurrentSkipListSet lower() method.
import java.util.concurrent.ConcurrentSkipListSet;
class GfgCSLS {
public static void main(String[] args)
{
// Initializing the set
// using ConcurrentSkipListSet()
ConcurrentSkipListSet<Integer>
set = new ConcurrentSkipListSet<Integer>();
// Adding elements to this set
// using add() method
set.add(17);
set.add(24);
set.add(35);
set.add(67);
set.add(98);
// Printing the ConcurrentSkipListSet
System.out.println("ConcurrentSkipListSet: "
+ set);
// Invoking lower() method
// to find the largest element
// less than the specified element
System.out.println("Largest element: "
+ set.lower(67));
}
}
輸出:
ConcurrentSkipListSet: [17, 24, 35, 67, 98] Largest element: 35
示例2:顯示NullpointerException
// Java program to demonstrate
// ConcurrentSkipListSet lower() method.
import java.util.concurrent.ConcurrentSkipListSet;
class GfgCSLS {
public static void main(String[] args)
{
// Initializing the set
// using ConcurrentSkipListSet()
ConcurrentSkipListSet<Integer>
set = new ConcurrentSkipListSet<Integer>();
// Adding elements to this set
// using add() method
set.add(17);
set.add(24);
set.add(35);
set.add(67);
set.add(98);
// Printing the ConcurrentSkipListSet
System.out.println("ConcurrentSkipListSet: "
+ set);
try {
// Invoking lower() method
// to find the largest element
// less than the specified element
System.out.println("Largest element: "
+ set.lower(null));
}
catch (Exception e) {
System.out.println(e);
}
}
}
輸出:
ConcurrentSkipListSet: [17, 24, 35, 67, 98] java.lang.NullPointerException
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注:本文由純淨天空篩選整理自ProgrammerAnvesh大神的英文原創作品 ConcurrentSkipListSet lower() method in Java with Examples。非經特殊聲明,原始代碼版權歸原作者所有,本譯文未經允許或授權,請勿轉載或複製。