Java 中的 concurrentlinkedrequeofflast()方法
原文:https://www . geeksforgeeks . org/concurrentlinkedeque-offer last-method-in-Java/
java . util . concurrentlinkedeque . offer last()方法是 Java 中的一个内置方法,它将作为参数传递的指定元素插入到 deque 的末尾。
语法:
Conn_Linked_Deque.offerLast*(Object elem)*
参数:该方法接受一个参数 elem ,该参数指定了要插入到数据末尾的元素。
返回值:如果元素成功添加到德格中,函数返回真,否则返回假。
异常:如果传递的参数为空,则函数抛出空指针异常。
下面的程序说明了concurrentlinkedequetofflast()方法:
程序 1 :
/* Java Program to Demonstrate offerLast()
method of ConcurrentLinkedDeque */
import java.util.concurrent.*;
class GFG {
public static void main(String[] args)
{
// Creating an empty Deque
ConcurrentLinkedDeque<String> cld =
new ConcurrentLinkedDeque<String>();
// Add elements into the Deque
cld.add("Welcome");
cld.add("To");
cld.add("Geeks");
cld.add("4");
cld.add("Geeks");
// Displaying the Deque
System.out.println("Elements in Deque: "
+ cld);
// Displaying the Last element
System.out.println("The Last element is: " +
cld.getLast());
/* Insert an element at the tail
of the deque */
if (cld.offerLast("GFG")) {
// Displaying the Last element
System.out.println("The Inserted element is: " +
cld.getLast());
}
// Displaying the Deque
System.out.println("Elements in Deque: "
+ cld);
// Displaying the Last element
System.out.println("The Last element is: " +
cld.getLast());
}
}
输出:
Elements in Deque: [Welcome, To, Geeks, 4, Geeks]
The Last element is: Geeks
The Inserted element is: GFG
Elements in Deque: [Welcome, To, Geeks, 4, Geeks, GFG]
The Last element is: GFG
程序二 :
/* Java Program to Demonstrate offerLast()
method of ConcurrentLinkedDeque */
import java.util.concurrent.*;
class GFG {
public static void main(String[] args)
{
// Creating an empty Deque
ConcurrentLinkedDeque<Integer> cld =
new ConcurrentLinkedDeque<Integer>();
// Add elements into the Deque
cld.add(12);
cld.add(43);
cld.add(29);
cld.add(16);
cld.add(70);
// Displaying the Deque
System.out.println("Elements in Deque: "
+ cld);
// Displaying the Last element
System.out.println("The Last element is: " +
cld.getLast());
try {
cld.offerLast(null);
}
catch (Exception e) {
System.out.println(e);
}
/* Insert an element at the tail
of the deque */
if (cld.offerLast(24)) {
// Displaying the Last element
System.out.println("The Inserted element is: "
+ cld.getLast());
}
// Displaying the Deque
System.out.println("Elements in Deque: "
+ cld);
// Displaying the Last element
System.out.println("The Last element is: " +
cld.getLast());
}
}
输出:
Elements in Deque: [12, 43, 29, 16, 70]
The Last element is: 70
java.lang.NullPointerException
The Inserted element is: 24
Elements in Deque: [12, 43, 29, 16, 70, 24]
The Last element is: 24
参考:https://docs . Oracle . com/javase/8/docs/API/Java/util/concurrentlinkedeque . html # offer last()
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