Print content of priority queue[java]

问题

How do I make the print_queue work properly in java? This is my own implementation of queue.

Using Iterator() works fine, except it prints numbers in random order.

package data_structures_java ;
import java.util.Iterator;
import java.util.PriorityQueue ;
import java.util.* ;
public class Queue_implementation {

    PriorityQueue<Integer> actual_queue ;

    public Queue_implementation(){
        actual_queue = new PriorityQueue<Integer>() ;

    }

    public  void add(int num){
        actual_queue.add(num) ;
    }

    public int remove(){
          return actual_queue.remove() ;          
    }

    public int peek(){
        if( actual_queue.isEmpty()) return -1 ;
        else return actual_queue.peek() ;
    }

    public int element(){
        return actual_queue.element() ;
    }

    public void print_queue(){      
        PriorityQueue<Integer>copy = new PriorityQueue<Integer>();
        copy.addAll(actual_queue) ;        
        Iterator<Integer> through = actual_queue.iterator() ;
        while(through.hasNext() ) {
                System.out.print(through.next() + " ") ;
        }
        System.out.println() ;

        actual_queue.addAll(copy) ;

    }
    public static void main(String[] args) {            
        Queue_implementation x = new Queue_implementation() ;
        x.add(10) ;
        x.add(9) ;
        x.add(8) ;
        x.add(7) ;
        x.add(6) ;
        x.print_queue() ;
    }

}

I tried to use toArray() but it returns Object[] , which I dont' know how to traverse:

Object[] queue_object_array = x.toArray() ;
Arrays.sort(queue_object_array) ;

回答1:

Using Iterator() works fine, except it prints numbers in random order.

That's exactly what it says it will do in the Javadoc. The only way to get the ordering in the PriorityQueue is to use the poll() or remove() methods.

回答2:

One line solution : useful when you need fast debugging.

System.out.println(Arrays.toString(priorityQueue.toArray()));

回答3:

You can convert the Priority Queue object into an array object. You can then print this array object.

Object[] arr = priorityQueue.toArray();

来源：https://stackoverflow.com/questions/22928255/print-content-of-priority-queuejava

标签

java

queue

priority-queue