Java LinkedBlockingDeque offerFirst()用法及代碼示例

LinkedBlockingDeque的offerFirst(E e)方法將在參數中傳遞的元素插入Deque容器的前麵。如果超出了容器的容量，則不會像add()和addFirst()函數一樣返回異常。

用法:

public boolean offer(E e)

參數：此方法接受強製參數e，該參數是要在LinkedBlockingDeque的前麵插入的元素。

返回值：如果已插入元素，則此方法返回true，否則返回false。

以下示例程序旨在說明LinkedBlockingDeque的offerFirst()方法：

示例1:

// Java Program Demonstrate offerFirst() 
// method of LinkedBlockingDeque 
  
import java.util.concurrent.LinkedBlockingDeque; 
import java.util.*; 
  
public class GFG { 
    public static void main(String[] args) 
        throws IllegalStateException 
    { 
  
        // create object of LinkedBlockingDeque 
        LinkedBlockingDeque<Integer> LBD 
            = new LinkedBlockingDeque<Integer>(4); 
  
        // Add numbers to end of LinkedBlockingDeque 
        LBD.offerFirst(7855642); 
        LBD.offerFirst(35658786); 
        LBD.offerFirst(5278367); 
        LBD.offerFirst(74381793); 
  
        // Cannot be inserted 
        LBD.offerFirst(10); 
  
        // cannot be inserted hence returns false 
        if (!LBD.offerFirst(10)) 
            System.out.println("The element 10 cannot be inserted"+ 
                                           " as capacity is full"); 
  
        // before removing print queue 
        System.out.println("Linked Blocking Deque: " + LBD); 
    } 
}

輸出：

The element 10 cannot be inserted as capacity is full
Linked Blocking Deque: [74381793, 5278367, 35658786, 7855642]

示例2:

// Java Program Demonstrate offerFirst() 
// method of LinkedBlockingDeque 
  
import java.util.concurrent.LinkedBlockingDeque; 
import java.util.*; 
  
public class GFG { 
    public static void main(String[] args) 
        throws IllegalStateException 
    { 
  
        // create object of LinkedBlockingDeque 
        LinkedBlockingDeque<String> LBD 
            = new LinkedBlockingDeque<String>(4); 
  
        // Add numbers to end of LinkedBlockingDeque 
        LBD.offerFirst("abc"); 
        LBD.offerFirst("gopu"); 
        LBD.offerFirst("geeks"); 
        LBD.offerFirst("richik"); 
  
        // Cannot be inserted 
        LBD.offerFirst("hii"); 
  
        // cannot be inserted hence returns false 
        if (!LBD.offerFirst("hii")) 
            System.out.println("The element 'hii' cannot be"
                           +" inserted as capacity is full"); 
  
        // before removing print queue 
        System.out.println("Linked Blocking Deque: " + LBD); 
    } 
}

輸出：

The element 'hii' cannot be inserted as capacity is full
Linked Blocking Deque: [richik, geeks, gopu, abc]

參考： https://docs.oracle.com/javase/7/docs/api/java/util/concurrent/LinkedBlockingDeque.html#offerFirst(E)

相關用法

注：本文由純淨天空篩選整理自gopaldave大神的英文原創作品 LinkedBlockingDeque offerFirst() method in Java。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。