迭代器(Iterator)遍历List、Set、Map

迭代器用来遍历List、Set、Map使用iterator()来返回一个Iterator使用next()获得序列中的下一个元素使用hasNext()检查序列中是否还有元素使用remove()将迭代器新近返回的元素删除

遍历list

System.out.println("迭代器:"); Iterator<String> it = lists.iterator(); while (it.hasNext()){ String obj = it.next(); System.out.println("value:"+obj); }

遍历set

Set<String> setList = new HashSet<String>(); setList.add("aaaaa"); setList.add("bbbbb"); System.out.println("迭代器遍历set:"); Iterator<String> itSet = setList.iterator(); while (itSet.hasNext()){ System.out.println("obj:"+itSet.next()); }

遍历map

Map<String,String> maps = new HashMap<>(); maps.put("aaa","111"); maps.put("bbb","222"); Set<Map.Entry<String,String>> entries = maps.entrySet(); Iterator<Map.Entry<String,String>> iteratorMap = entries.iterator(); while (iteratorMap.hasNext()){ Map.Entry<String,String> next = iteratorMap.next(); System.out.println(next); } Map<String,String> maps = new HashMap<>(); maps.put("aaa","111"); maps.put("bbb","222"); Set<String> entries = maps.keySet(); Iterator<String> iteratorMap = entries.iterator(); while (iteratorMap.hasNext()){ String next = iteratorMap.next(); System.out.println(next); } Map<String,String> maps = new HashMap<>(); maps.put("aaa","111"); maps.put("bbb","222"); Collection<String> entries = maps.values(); Iterator<String> iteratorMap = entries.iterator(); while (iteratorMap.hasNext()){ String next = iteratorMap.next(); System.out.println(next); }