HashMap和List遍历方法及如何遍历删除元素总结

List<String> list= new ArrayList<String>();
  famous.add("zs");
  famous.add("ls");
  famous.add("ww");
  famous.add("dz");

 for(int i=0;i<list.size();i++){
       if(list.get(i).equals("ls"))
       list.remove(i);
      }

    for(String x:list){
      if(x.equals("ls"))
      list.remove(x);
    }

for(Iterator<String> it = list.iterator();it.hasNext();){
     String s = it.next();
     if(s.equals("madehua")){
       list.remove(s);
     }
   }

private class Itr implements Iterator<E> {
	    int cursor;    // index of next element to return
	    int lastRet = -1; // index of last element returned; -1 if no such
	    int expectedModCount = modCount;
 
 
	    public boolean hasNext() {
	      return cursor != size; // size为集合中元素的个数
	    }
 
 
	    public E next() {
	      checkForComodification();
	      int i = cursor;
	      if (i >= size)
	        throw new NoSuchElementException();
	      Object[] elementData = ArrayList.this.elementData;
	      if (i >= elementData.length)
	        throw new ConcurrentModificationException();
	      cursor = i + 1;
	      return (E) elementData[lastRet = i];
	    }
 
 
	    /* 此方法并没被调用，只是调用List.remove方法
	    public void remove() {
	      checkForComodification();
	      try {
	        ArrayList.this.remove(lastRet);	// size字段减1
	        cursor = lastRet;
	        lastRet = -1;
	        expectedModCount = modCount;
	      } catch (IndexOutOfBoundsException ex) {
	        throw new ConcurrentModificationException();
	      }
	    }
	    */
 
 
	    final void checkForComodification() {	// 检查修改和当前版本号是否一致，不一致则抛出异常
	      if (modCount != expectedModCount)
	        throw new ConcurrentModificationException();
	    }
 
 
  	}
 
 
  	// List.remove
  	@Override public boolean remove(Object object) {
	    Object[] a = array;
	    int s = size;
	    if (object != null) {
	      for (int i = 0; i < s; i++) {
	        if (object.equals(a[i])) {
	          System.arraycopy(a, i + 1, a, i, --s - i);
	          a[s] = null; // Prevent memory leak
	          size = s;
	          modCount++;	// 核心代码：修改了版本号。这样当checkForComodification的时候，modCount值就和expectedModCount不同
	          return true;
	        }
	      }
	    } else {
	      for (int i = 0; i < s; i++) {
	        if (a[i] == null) {
	          System.arraycopy(a, i + 1, a, i, --s - i);
	          a[s] = null; // Prevent memory leak
	          size = s;
	          modCount++;
	          return true;
	        }
	      }
	    }
	    return false;
	  }

   Iterator<String> it = list.iterator();
   while(it.hasNext()){
    String x = it.next();
    if(x.equals("del")){
      it.remove();
   }
  }

	private static HashMap<Integer, String> map = new HashMap<Integer, String>();;
 
	public static void main(String[] args) {
		
		 for(int i = 0; i < 10; i++){ 
	      map.put(i, "value" + i); 
	    } 
	 
	
	}

    for(Map.Entry<Integer, String> entry : map.entrySet()){ 
       Integer key = entry.getKey(); 
       if(key % 2 == 0){ 
         System.out.println("To delete key " + key); 
         map.remove(key); 
         System.out.println("The key " + + key + " was deleted"); 
       } 

    Set<Integer> keySet = map.keySet();
	   for(Integer key : keySet){
	      if(key % 2 == 0){
	        System.out.println("To delete key " + key);
	        keySet.remove(key);
	        System.out.println("The key " + + key + " was deleted");
	      }
	   }

  Iterator<Map.Entry<Integer, String>> it = map.entrySet().iterator();
    while(it.hasNext()){
      Map.Entry<Integer, String> entry = it.next();
      Integer key = entry.getKey();
      if(key % 2 == 0){
      	 System.out.println("To delete key " + key);
      	 it.remove();  
      	 System.out.println("The key " + + key + " was deleted");
 
      }
    }