用示例
链接 Java 中的 deblockingdequedrainto()方法
原文:https://www . geeksforgeeks . org/link edblockingeque-drain to-method-in-Java-with-example/
linkedblockingrequest 的 drainTo(Collection col) 方法从该 linkedblockingrequest 中移除所有可用元素，并将它们添加到作为参数传递的给定集合中。
排水(集合〔t0〕col)
LinkedBlockingDeque 的drain to(Collectioncol)方法将从该查询中移除所有元素，并将它们添加到给定的集合 col 中。这是比重复轮询该查询更有效的方法。
在尝试从 deque 向集合 c 添加元素时也有可能遇到失败，并且由于该失败，当引发相关联的异常时，元素会分布在两个集合之间。如果一个 decue 试图将 drainTo()排到 decue 本身，那么将引发 IllegalArgumentException。如果在操作过程中修改了指定的集合，则此操作的行为是未定义的。因此，为了使用这样的方法，需要注意这种类型的情况来克服异常。
语法:
public int drainTo(Collection<? super E> col)
参数:该方法接受一个参数列，该参数代表从 link edblockingrequest 转移元素的集合。
返回值:该方法返回从 deque 排入集合的元素数量。
异常:该方法抛出以下异常:
- 取消支持操作异常–如果集合无法添加元素。
- class castexception–如果元素的类停止了向集合中添加元素的方法。
- 空指针异常–如果集合为空
- IllegalArgumentException–如果方法的参数阻止它被添加到指定的集合中
下面的程序说明了 LinkedBlockingDeque 类的 drainTo()方法:
程序 1:
下面的程序有一个存储雇员对象的链接锁定请求。有一个数组列表，它将存储 linkedblockingrequest 中的所有员工对象。所以 drainTo()与 linkedblockingrequest 一起使用，将所有雇员从 deque 传递到 ArrayList。
// Java Program Demonstrate drainTo(Collection c)
// method of LinkedBlockingDeque.
import java.util.ArrayList;
import java.util.concurrent.LinkedBlockingDeque;
public class GFG {
// create a Employee Object with
// position and salary as an attribute
public class Employee {
public String name;
public String position;
public String salary;
Employee(String name, String position, String salary)
{
this.name = name;
this.position = position;
this.salary = salary;
}
@Override
public String toString()
{
return "Employee [name=" + name + ", position="
+ position + ", salary=" + salary + "]";
}
}
// Main Method
public static void main(String[] args)
{
GFG gfg = new GFG();
gfg.containsMethodExample();
}
public void containsMethodExample()
{
// define capacity of LinkedBlockingDeque
int capacity = 50;
// create object of LinkedBlockingDeque
LinkedBlockingDeque<Employee> linkedDeque
= new LinkedBlockingDeque<Employee>(capacity);
// create a ArrayList to pass as parameter to drainTo()
ArrayList<Employee> collection
= new ArrayList<Employee>();
// add Employee object to deque
Employee emp1 = new Employee("Aman", "Analyst", "24000");
Employee emp2 = new Employee("Sachin", "Developer", "39000");
linkedDeque.add(emp1);
linkedDeque.add(emp2);
// printing Arraylist and deque
System.out.println("Before drainTo():");
System.out.println("LinkedBlockingDeque : \n"
+ linkedDeque.toString());
System.out.println("ArrayList : \n"
+ collection);
// Apply drainTo method and pass collection as parameter
int response = linkedDeque.drainTo(collection);
// print no of element passed
System.out.println("\nNo of element passed: "
+ response);
// printing Arraylist and deque
// after applying drainTo() method
System.out.println("\nAfter drainTo():");
System.out.println("LinkedBlockingDeque : \n"
+ linkedDeque.toString());
System.out.println("ArrayList : \n"
+ collection);
}
}
Output:
Before drainTo():
LinkedBlockingDeque :
[Employee [name=Aman, position=Analyst, salary=24000], Employee [name=Sachin, position=Developer, salary=39000]]
ArrayList :
[]
No of element passed: 2
After drainTo():
LinkedBlockingDeque :
[]
ArrayList :
[Employee [name=Aman, position=Analyst, salary=24000], Employee [name=Sachin, position=Developer, salary=39000]]
程序 2: 显示 drainTo()方法引发的异常的程序。
// Java Program Demonstrate
// drainTo(Collection C)
// method of LinkedBlockingDeque.
import java.util.ArrayList;
import java.util.concurrent.LinkedBlockingDeque;
public class GFG {
public static void main(String[] args)
throws InterruptedException
{
// define capacity of LinkedBlockingDeque
int capacityOfDeque = 4;
// create object of LinkedBlockingDeque
LinkedBlockingDeque<Integer> linkedDeque
= new LinkedBlockingDeque<Integer>(capacityOfDeque);
// add elements to deque
linkedDeque.put(85461);
linkedDeque.put(44648);
linkedDeque.put(45654);
// create a collection with null
ArrayList<Integer> add = null;
// try to drain null deque to collection
try {
linkedDeque.drainTo(add);
}
catch (Exception e) {
System.out.println("Exception: " + e);
}
}
}
Output:
Exception: java.lang.NullPointerException
排水(集合 super E> col，int maxElements)
沥水(收藏<？super E > col，int maxElements) 用于将在 drainTo()中作为整数传递的定数元传递给集合，集合也作为参数传递给方法。转移元素后，LinkedBlockingDeque 只有那些没有转移到集合的元素。该函数与上面的函数相同，只是在传递固定数量的元素时有一些限制。
语法:
public int drainTo(Collection<E> col, int maxElements)
参数:该方法接受两个参数:
- 列–表示从 link edblockingrequest 转移元素的集合。
- maxElements–这是整数类型，是指要传输到集合中的元素的最大数量。
返回值:该方法返回元素的数量从排到从德格收集。
异常:该方法抛出以下异常:
- 取消支持操作异常–如果集合无法添加元素。
- class castexception-如果元素的类停止向集合中添加元素的方法。
- 空指针异常–如果集合为空
- IllegalArgumentException–如果方法的参数阻止它被添加到指定的集合中
下面的程序说明了 LinkedBlockingDeque 类的 drainTo(Collection super E> col，int maxElements)方法
程序 1:
下面的程序有一个存储员工对象的链接锁定请求，还有一个存储链接锁定请求中所有员工对象的哈希集。所以 LinkedBlockingDeque 的 drainTo()用于将某个员工从 Deque 传递到 ArrayList。因此，没有要传输的元素作为参数在方法中传递。
// Java program to demonstrate drainTo()
// method of LinkedBlockingDeque.
import java.util.*;
import java.util.concurrent.LinkedBlockingDeque;
public class GFG {
// create an Employee Object with
// position and salary as attribute
public class Employee {
public String name;
public String position;
public String salary;
Employee(String name, String position, String salary)
{
this.name = name;
this.position = position;
this.salary = salary;
}
@Override
public String toString()
{
return "Employee [name=" + name + ", "
+ "position=" + position
+ ", salary=" + salary + "]";
}
}
// Main Method
public static void main(String[] args)
{
GFG gfg = new GFG();
gfg.containsMethodExample();
}
public void containsMethodExample()
{
// define capacity of LinkedBlockingDeque
int capacity = 10;
// create object of LinkedBlockingDeque
LinkedBlockingDeque<Employee> linkedDeque
= new LinkedBlockingDeque<Employee>(capacity);
// create a HashSet to pass as parameter to drainTo()
HashSet<Employee> collection
= new HashSet<Employee>();
// add Employee object to deque
Employee emp1 = new Employee("Sachin",
"Analyst",
"40000");
Employee emp2 = new Employee("Aman",
"Developer",
"69000");
Employee emp3 = new Employee("Kajal",
"Accountant",
"39000");
linkedDeque.add(emp1);
linkedDeque.add(emp2);
linkedDeque.add(emp3);
// printing Arraylist and deque
// before applying drainTo() method
System.out.println("Before drainTo():");
System.out.println("No of Elements in Deque is "
+ linkedDeque.size());
System.out.println("Elements in Deque is as follows");
Iterator<Employee> listOfemp
= linkedDeque.iterator();
while (listOfemp.hasNext())
System.out.println(listOfemp.next());
System.out.println("No of Elements in HashSet is "
+ collection.size());
System.out.println("Elements in HashSet is as follows:");
for (Employee emp : collection)
System.out.println(emp);
// Initialize no of element passed to collection
// using drainTo() method
int noOfElement = 2;
// Apply drainTo method
// and pass collection as parameter
int response
= linkedDeque.drainTo(collection, noOfElement);
// print no of element passed
System.out.println("\nNo of element passed: "
+ response);
// printing Arraylist and deque
// after applying drainTo() method
System.out.println("\nAfter drainTo():");
System.out.println("No of Elements in Deque is "
+ linkedDeque.size());
System.out.println("Elements in Deque is as follows");
listOfemp = linkedDeque.iterator();
while (listOfemp.hasNext())
System.out.println(listOfemp.next());
System.out.println("No of Elements in HashSet is "
+ collection.size());
System.out.println("Elements in HashSet is as follows:");
for (Employee emp : collection)
System.out.println(emp);
}
}
Output:
Before drainTo():
No of Elements in Deque is 3
Elements in Deque is as follows
Employee [name=Sachin, position=Analyst, salary=40000]
Employee [name=Aman, position=Developer, salary=69000]
Employee [name=Kajal, position=Accountant, salary=39000]
No of Elements in HashSet is 0
Elements in HashSet is as follows:
No of element passed: 2
After drainTo():
No of Elements in Deque is 1
Elements in Deque is as follows
Employee [name=Kajal, position=Accountant, salary=39000]
No of Elements in HashSet is 2
Elements in HashSet is as follows:
Employee [name=Sachin, position=Analyst, salary=40000]
Employee [name=Aman, position=Developer, salary=69000]
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