地图 set stack

map set stack
set 和 map 的遍历

Map<String, String> map = new HashMap<String, String>();
map.put("1", "a");
map.put("2", "b");
map.put("3", "c");

//map最简洁、最通用的遍历方式1
for (Map.Entry<String, String> entry : map.entrySet()) {
System.out.println(entry.getKey() + " = " + entry.getValue());
}


//map的遍历方法2
Set<String> set = map.keySet();
for(String s:set){
System.out.println(s + "," + map.get(s));
}
//map的遍历方法3
Iterator<String> it = map.keySet().iterator();
while(it.hasNext()){
System.out.println(map.get(it.next()));
}

//map的遍历方法4
Iterator it = map.values().iterator();
while(it.hasNext()){
String val = (String)it.next();
System.out.println(val);
}
}

//set的遍历HashSet hashSet=new HashSet();
  String a=new String("A");
  String b=new String("B");
  String c=new String("B");
  hashSet.add(a);
  hashSet.add(b);
Iterator ir=hashSet.iterator();
  while(ir.hasNext())
  {
   System.out.println(ir.next());
  }

操作set的一些方法：
hashSet的大小"+hashSet.size();
boolean hashSet.add(Object e) ;
boolean hashSet.isEmpty();
boolean hashSet.contains(Object e);
boolean hashSet.remove(Object e);

栈的遍历：Stack<Integer> s = new Stack<Integer>();
for (int i = 0; i < 10; i++) {
s.push(i);
}
//集合遍历方式
for (Integer x : s) {
System.out.println(x);
}
//栈弹出遍历方式
while (!s.empty()) {
System.out.println(s.pop());
}
//队列的遍历
Queue<Integer> q = new LinkedBlockingQueue<Integer>();
//初始化队列
for (int i = 0; i < 5; i++) {
q.offer(i);
}
//集合方式遍历，元素不会被移除
for (Integer x : q) {
System.out.println(x);
}
//队列方式遍历，元素逐个被移除
while (q.peek() != null) {
System.out.println(q.poll());
}