java集合类（二）List学习

class iphone{} 
	
public void arraylist(){
	//1)Constructs an empty list with an initial capacity of ten
	ArrayList al = new ArrayList();
	/*
	 * 2)Constructs a list containing the elements of the specified 
	 * collection, in the order they are returned by the collection's iterator
	*/
	ArrayList<Integer> alist = new ArrayList(Arrays.asList(1,2,3));
	//3)Constructs an empty list with the specified initial capacity
	ArrayList<Double> alist1 = new ArrayList(10);
	al.add(new iphone());
	al.add(1);
	al.add("a");
	al.add(alist);
	System.out.println(al.hashCode()); //int hashcode()
		
	/*
	 * usage of methods that aren't mentioned within "List basic methods"
	 */
	//ensure that list can hold at least the number of elements specified by the minimum capacity argument
	alist1.ensureCapacity(30);
	//Trims the capacity of this ArrayList instance to be the list's current size
	alist.trimToSize();
        
        //Returns a shallow copy of this ArrayList instance(The elements themselves are not copied)
        Object o = al.clone();
}

public void linkedlist(){
	LinkedList linklist = new LinkedList();
	ArrayList<Integer> a = new ArrayList(Arrays.asList(1,2,3));
	LinkedList linklist2 = new LinkedList(a);
		
	Iterator i = linklist2.iterator();
	while(i.hasNext()){
		System.out.println(i.next());   //1  2  3
	}
	Iterator ri = linklist2.descendingIterator();
	while(ri.hasNext()){
		System.out.println(ri.next());   //3  2  1
	}
		
	linklist.addFirst(1);
	linklist.addLast("e");
	System.out.println(linklist);  //[1,e]  
	/*linklist.getFirst();
	linklist.getLast();*/
		
	//Retrieves, but does not remove, the head (first element) of this list
	System.out.println(linklist.element());  //1
		
	linklist.offer("x");
	System.out.println(linklist);//[1,e,x]
	linklist.offerFirst(0);
	linklist.offerLast("y");
	System.out.println(linklist);//[0,1,e,x,y]
		
	//peek..()--->[Retrieves, but does not remove]
	System.out.println(linklist.peek());//0
	System.out.println(linklist.peekFirst());//0 ,list is empty,return "null"
	System.out.println(linklist.peekLast());//y,list is empty, return "null"
		
	//poll..()--->[Retrieves and removes]
	System.out.println(linklist.poll()); //0
	System.out.println(linklist.pollFirst());//1
	System.out.println(linklist.pollLast()); //y
	System.out.println(linklist);//[e,x]
		
	/*linklist.removeFirst();    //return first element
	linklist.removeFirstOccurrence(Object);   //boolean
	linklist.removeLast();   //return last element
	linklist.removeLastOccurrence(Object);  //boolean
	*/ 
		
	System.out.println(linklist2); //[1  2  3]
	//Pops an element from the stack represented by this list
	System.out.println(linklist2.pop()); //1
	//Pushes an element onto the stack represented by this list
	linklist2.push("m"); 
	System.out.println(linklist2);//[m,2,3]
	}

public void comparearraylistwithlinklist(){
	SimpleDateFormat f = new SimpleDateFormat("yyyy-MM-dd  hh:mm:ss");
	System.out.println(f.format(new Date()));
	    
	ArrayList<Integer> a = new ArrayList<Integer>();
	long starttime = new Date().getTime();
	for(int i = 0; i<10000; i++){
		a.add(i);
	}
	long finishtime = new Date().getTime();
	System.out.println(finishtime-starttime);
		
	LinkedList<Integer> l = new LinkedList<Integer>();
	long lstarttime = new Date().getTime();
	for(int i = 0; i<10000; i++){
		l.add(i);
	}
	long lfinishtime = new Date().getTime();
	System.out.println(lfinishtime-lstarttime);
}