PriorityQueue 的用法

PriorityQueue 是一種資料結構。與 SortedSet 一樣，PriorityQueue 也根據其優先順序對其元素進行排序。具有較高優先順序的元素首先出現。PriorityQueue 的型別應該實現 comparable 或 comparator 介面，其方法決定資料結構元素的優先順序。

//The type of the PriorityQueue is Integer.
PriorityQueue<Integer> queue = new PriorityQueue<Integer>();

//The elements are added to the PriorityQueue
queue.addAll( Arrays.asList( 9, 2, 3, 1, 3, 8 ) );

//The PriorityQueue sorts the elements by using compareTo method of the Integer Class
//The head of this queue is the least element with respect to the specified ordering
System.out.println( queue );  //The Output: [1, 2, 3, 9, 3, 8]
queue.remove();
System.out.println( queue );  //The Output: [2, 3, 3, 9, 8]
queue.remove();
System.out.println( queue );  //The Output: [3, 8, 3, 9]
queue.remove();
System.out.println( queue );  //The Output: [3, 8, 9]
queue.remove();
System.out.println( queue );  //The Output: [8, 9]
queue.remove();
System.out.println( queue );  //The Output: [9]
queue.remove();
System.out.println( queue );  //The Output: []