极客教程Java BlockingQueue remainingCapacity()方法及示例
BlockingQueue 的 remainCapacity() 方法返回可以添加到BlockingQueue而不阻塞的元素数量。
返回的容量在三种情况下会出现。
- 如果剩余容量为零，那么就没有更多的元素可以被添加到BlockingQueue中。
- 如果BlockingQueue的剩余容量等于队列的大小，那么就不能从队列中移除任何元素，因为在这种情况下队列是空的。
- 在任何其他情况下，Capacity总是等于这个BlockingQueue的初始容量和这个BlockingQueue的当前大小之间的差。
语法
public int remainingCapacity()
返回值： 该方法返回BlockingQueue的剩余容量。
注意 ： BlockingQueue 的 remainCapacity() 方法是从Java的 Queue 类中继承来的。
下面的程序说明了BlockingQueue类的remainCapacity()方法。
程序1:
// Java Program Demonstrate remainingCapacity()
// method of BlockingQueue
import java.util.concurrent.LinkedBlockingQueue;
import java.util.concurrent.BlockingQueue;
public class GFG {
public static void main(String[] args)
{
// define capacity of BlockingQueue
int capacityOfQueue = 7;
// create object of BlockingQueue
BlockingQueue<String> BQ
= new LinkedBlockingQueue<String>(
capacityOfQueue);
// Add element to BlockingQueue
BQ.add("John");
BQ.add("Tom");
BQ.add("Clark");
BQ.add("Kat");
// find remaining Capacity of BQ
// using remainingCapacity() method
int remainingCapacity
= BQ.remainingCapacity();
// print result
System.out.println("Queue is " + BQ);
// print head of the queue
System.out.println("Remaining Capacity of Queue is "
+ remainingCapacity);
}
}
输出。
Queue is [John, Tom, Clark, Kat]
Remaining Capacity of Queue is 3
程序2。
// Java Program Demonstrate remainingCapacity()
// method of BlockingQueue
import java.util.concurrent.LinkedBlockingQueue;
import java.util.concurrent.BlockingQueue;
public class GFG {
public void findPeek()
{
// define capacity of BlockingQueue
int capacityOfQueue = 7;
// create object of BlockingQueue
BlockingQueue<Employee> BQ
= new LinkedBlockingQueue<Employee>(
capacityOfQueue);
// Add element to BlockingQueue
Employee emp1
= new Employee("Ravi", "Tester", "39000");
Employee emp2
= new Employee("Sanjeet", "Manager", "98000");
// Add Employee Objects to BQ
BQ.add(emp1);
BQ.add(emp2);
// add element and find remaining capacity
// follow same process again
// until the queue becomes full
while (BQ.size() != 7) {
// adding emp2 again and again to queue
System.out.println(
"Adding employee is success "
+ BQ.offer(emp2));
// find remaining capacity of BQ
// using remainingCapacity() method
int remain = BQ.remainingCapacity();
// print remaining capacity value
System.out.println(
"Remaining Capacity of list :"
+ remain);
}
}
// create an Employee Object with name,
// 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.findPeek();
}
}
输出。
Adding employee is success true
Remaining Capacity of list :4
Adding employee is success true
Remaining Capacity of list :3
Adding employee is success true
Remaining Capacity of list :2
Adding employee is success true
Remaining Capacity of list :1
Adding employee is success true
Remaining Capacity of list :0
**参考资料: ** https://docs.oracle.com/javase/7/docs/api/java/util/concurrent/BlockingQueue.html#remainingCapacity()