Java BlockingDeque push()方法及示例
BlockingDeque 的 push(E e) 方法将一个元素推到这个deque所代表的栈上。如果有空间的话,它会将参数中传递的元素插入到Deque的前面。如果BlockingDeque有容量限制,没有空间可供插入,它将返回一个IllegalStateException。这个函数类似于addFirst()的函数。
语法
public void push(E e)
参数: 该方法接受一个强制参数 e ,它是要插入到LinkedBlockingDeque前面的元素。
注意 : BlockingDeque 的push()方法已经从Java中的LinkedBlockingDeque类继承。
返回: 该方法不返回任何东西。
异常
- IllegalStateException : 如果由于容量的限制,元素在这个时候不能被添加。
- NullPointerException :如果指定的元素为空。
以下程序说明了BlockingDeque的push()方法。
程序1 :
// Java Program Demonstrate push()
// method of BlockingDeque
import java.util.concurrent.LinkedBlockingDeque;
import java.util.concurrent.BlockingDeque;
import java.util.*;
public class GFG {
public static void main(String[] args)
throws IllegalStateException
{
// create object of BlockingDeque
BlockingDeque<Integer> BD
= new LinkedBlockingDeque<Integer>();
// Add numbers to end of BlockingDeque
BD.push(7855642);
BD.push(35658786);
BD.push(5278367);
BD.push(74381793);
// before removing print queue
System.out.println("Blocking Deque: " + BD);
}
}
输出
Blocking Deque: [74381793, 5278367, 35658786, 7855642]
程序2 :
// Java Program Demonstrate push()
// method of BlockingDeque
// when it is Full
import java.util.concurrent.LinkedBlockingDeque;
import java.util.concurrent.BlockingDeque;
import java.util.*;
public class GFG {
public static void main(String[] args)
throws IllegalStateException
{
// create object of BlockingDeque
// size of list
BlockingDeque<Integer> LBD
= new LinkedBlockingDeque<Integer>(3);
// Add numbers to end of BlockingDeque
BD.push(7855642);
BD.push(35658786);
BD.push(5278367);
// it is full
BD.push(74381793);
// before removing print queue
System.out.println("Blocking Deque: " + BD);
}
}
输出
Exception in thread "main" java.lang.IllegalStateException: Deque full
at java.util.concurrent.LinkedBlockingDeque.addFirst(LinkedBlockingDeque.java:326)
at java.util.concurrent.LinkedBlockingDeque.push(LinkedBlockingDeque.java:770)
at GFG.main(GFG.java:24)
程序3 :
// Java Program Demonstrate push()
// method of BlockingDeque
// when null is inserted
import java.util.concurrent.LinkedBlockingDeque;
import java.util.concurrent.BlockingDeque;
import java.util.*;
public class GFG {
public static void main(String[] args)
throws IllegalStateException
{
// create object of BlockingDeque
BlockingDeque<Integer> BD
= new LinkedBlockingDeque<Integer>();
// Add numbers to end of BlockingDeque
BD.push(7855642);
BD.push(35658786);
BD.push(5278367);
// NULL
BD.push(null);
// before removing print Deque
System.out.println("Blocking Deque: " + BD);
}
}
输出
Exception in thread "main" java.lang.NullPointerException
at java.util.concurrent.LinkedBlockingDeque.offerFirst(LinkedBlockingDeque.java:342)
at java.util.concurrent.LinkedBlockingDeque.addFirst(LinkedBlockingDeque.java:325)
at java.util.concurrent.LinkedBlockingDeque.push(LinkedBlockingDeque.java:770)
at GFG.main(GFG.java:24)
**参考资料: **https: //docs.oracle.com/javase/7/docs/api/java/util/concurrent/BlockingDeque.html#push(E)