JAva反復器はList、Set、Mapを遍歴する
2318 ワード
public class test {
public static void main(String[]args)
{
iteratorlist();
iteratorset();
iteratormap();
}
//** List**
*Iterator it* String
*list.iterator()* list
*Iterator it=list.iterator()* , int i=0
*it.hasNext()*
*it.next()* ,
public static void iteratorlist()
{
List list=new ArrayList<>();
list.add("aa");
list.add("bb");
list.add("cc");
// , int i=0;
for(Iterator it=list.iterator();it.hasNext();) // ,
{
String s=it.next(); // ,
System.out.println(s);
}
}
**// Set**
public static void iteratorset()
{
Set set= new HashSet<>();
set.add("dd");
set.add("ee");
set.add("ff");
for(Iterator it=set.iterator(); it.hasNext();)
{
String s=it.next();
System.out.println(s);
}
}
**// Map**
* map.entrySet() Map , *
*Entry *
* Set> Set ,Set *
*Iterator> it Set *
* Entry s=it.next(); it.next() *
* s.getKey() *
*s.getValue() *
public static void iteratormap()
{
Map map=new HashMap<>();
map.put(1,"gg");
map.put(2,"hh");
map.put(3, "ii");
**// **
Set> ss=map.entrySet(); //map , entrySet()
//
for(Iterator> it=ss.iterator();it.hasNext();)
{
Entry s=it.next();
System.out.println(s.getKey()+"+"+s.getValue());
}
** // , **
Set ss=map.keySet();
Map map.get(key) ,
Set ss=map.keySet();
for(Iterator it=ss.iterator();it.hasNext();)
{
Integer i=it.next();
System.out.println(i+"+"+map.get(i));
}
}
}