Java系列，《Java核心技术 卷1》，chapter 13，集合

    it.remove();
    it.remove();//error
    而是应该
    it.remove();    
    it.next();
    it.remove();

import java.util.ArrayList;
import java.util.Collection;
import java.util.Iterator;
public class LearnCollection {
	public static void main(String[] args) {
		// TODO Auto-generated method stub
		ArrayList<String> nameList = new ArrayList<String>();
		nameList.add("zhang.san");
		nameList.add("li.si");
		nameList.add("wang.wu");
		nameList.add("zhao.yi");
		
		System.out.println("initial content.");
		printCollection(nameList);	
		printViaIterator(nameList.iterator());

		removeViaIterator(nameList.iterator(), "li.si");
		
		System.out.println("");
		System.out.println("after remove li.si");
		printCollection(nameList);
		printViaIterator(nameList.iterator());
	}
	
	/**
	 * remove via iterator
	 * @param it
	 * @param value
	 */
	static void removeViaIterator(Iterator<?> it, String value){
		while(it.hasNext()){
			if(it.next().toString() == value){
				it.remove();
				System.out.println(String.format("remove %s success.", value));
				return;
			}				
		}			
		System.out.println(String.format("remove %s failed.", value));
	}
	/** 
	 * @param it
	 */
	static void printViaIterator(Iterator<?> it){
		System.out.println("Print via iterator:");
		while(it.hasNext())
			System.out.println(String.format("\titem:%s", it.next().toString()));
	}
	
	/**
	 * @param collection
	 */
	static void printCollection(Collection<?> collection){
		System.out.println("collection content:");
		for(Object item: collection){
			System.out.println(String.format("\titem:%s", item.toString()));
		}
	}
}

static void testToArray(){		
		LinkedList<String> strList = new LinkedList<String>();
		strList.add("zhang.san");
		strList.add("li.si");
		strList.add("wang.wu");
		print("filled array is not large enough.");
		testToArrayHelper(strList, new String[2]);
		
		print("filled array is large enough.");
		testToArrayHelper(strList, new String[3]);
	}
static void testToArrayHelper(LinkedList<String> strList, String[] filledArray){		
		String[] returnedArray = strList.toArray(filledArray);
		printArray("filled array:", filledArray);
		print("");
		printArray("returned array:", returnedArray);
		print("");
		if(filledArray == returnedArray)
			print("filled array is equal returned array.");
		else
			print("filled array is not equal returned array.");
	}
static <T> void printArray(String title, T[] array){
		print(title);
		for(T item: array){
			if(item != null)
				print("item:" + item.toString());
			else
				print("item is null");
		}
	}
static void print(String info){
		System.out.println(info);
	}

filled array is not large enough.
filled array:
item is null
item is null
returned array:
item:zhang.san
item:li.si
item:wang.wu
filled array is not equal returned array.
filled array is large enough.
filled array:
item:zhang.san
item:li.si
item:wang.wu
returned array:
item:zhang.san
item:li.si
item:wang.wu
filled array is equal returned array.

init content:
collection content:
	item:1
	item:2
	item:3
after insert 2 item
collection content:
	item:1
	item:1.1
	item:1.2
	item:2
	item:3

	static void testListIteratorRemove(){
		LinkedList<String> strList = new LinkedList<String>();
		strList.add("1");
		strList.add("2");
		strList.add("3");
		print("init content:");
		printCollection(strList);
		
		ListIterator<String> it = strList.listIterator();
		it.next();
		it.remove();//ok		
		
		print("after remove 1 item");
		printCollection(strList);
		
		it.remove();//error
		print("after remove 2 item");
		printCollection(strList);
	}

init content:
collection content:
	item:1
	item:2
	item:3
after remove 1 item
collection content:
	item:2
	item:3
Exception in thread "main" java.lang.IllegalStateException
	at java.util.LinkedList$ListItr.remove(LinkedList.java:923)
	at me.ygc.javabasic.learnJava.LearnCollection.testListIteratorRemove(LearnCollection.java:33)
	at me.ygc.javabasic.learnJava.LearnCollection.main(LearnCollection.java:15)