keyset()是获取所有的key值，iterator()是迭代遍历，keySet().iterator()返回一个hm.keySet ()的迭代。
java的keySetjava的keyset方法 keySet()方法的源码为:public Set<K>keySet() { Set<K> ks =keySet; if (ks == null) { ks = newKeySet();keySet= ks; } return ks; }注释为: java的keySet Java HashMap 迭代器 结点 转载 小蝌蚪 2023-08-24 12:25:53 ...
1importjava.util.Calendar;2importjava.util.Date;3importjava.util.HashMap;4importjava.util.Iterator;5importjava.util.Map.Entry;67/**8* 测试keySet()与entrySet()的迭代时间9* keySet():迭代后只能通过get()取key10* entrySet():迭代后可以e.getKey(),e.getValue()取key和value。返回的是Entry接口11...
* Returns an iterator over the elements in this set. The elements * are returned in no particular order. * * @return an Iterator over the elements in this set * @see ConcurrentModificationException */ public Iterator iterator() { return map.keySet().iterator(); } /** * Returns the num...
1.keySet() Map map=new HashMap(); Iterator it=map.keySet().iterator(); Object key; Object value; while(it.hasNext()){ key=it.next(); value=map.get(key); System.out.println(key+":"+value); } 2.entrySet() Map map=new HashMap(); ...
该集由映射提供支持,因此对映射所做的更改将反映在集中,反之亦然。 如果在对集进行迭代时修改了映射(除非通过迭代器自己的remove操作),则迭代的结果是未定义的。 该集支持通过 、、、retainAll和clear操作从映射Iterator.remove中删除相应映射removeAll的元素删除。Set.remove它不支持add或addAll操作。
iterator in interface Iterable<Object> Specified by: iterator in interface Set<Object> toArray public Object[] toArray() Deprecated. Specified by: toArray in interface Collection<Object> Specified by: toArray in interface Set<Object> toArray public <T> T[] toArray(...
iterator(); while(it.hasNext()) { Map.Entry<Integer,Integer> entry=it.next(); int key=entry.getKey(); int value=entry.getValue(); System.out.println(key+" "+value); } 2. entrySet entrySet是 java中 键-值 对的集合,Set里面的类型是Map.Entry,一般可以通过map.entrySet()得到。
Iterator it = people.iterator(); ...
Method Summary boolean add(Object o) Iterator iterator() int size() protected Object writeReplace() Methods inherited from class java.util.AbstractSet equals, hashCode, removeAllMethods inherited from class java.util.AbstractCollection addAll, clear, contains, containsAll, isEmpty, remove, retain...