list的遍历方式:
ArrayList<String> al = new ArrayList<String>();
al.add("java01");
al.add("java02");
al.add("java03");
al.add("java04");
System.out.println("元集合"+al);
//List的第一种遍历方式:因为list有顺序,利用size()和get()方法获取
for (int i = 0; i < al.size(); i++) {
System.out.println(al.get(i));
}
//List的第二种遍历方式:利用Iterator
Iterator<String> his =al.iterator();
while(his.hasNext())
{
System.out.println(his.next());
}
//List的第三种遍历方式:利用foreach
for(String s1 : al)
{
System.out.println(s1);
}
set的遍历方式:
Set<String> set = new HashSet<String>();
set.add("AAA");
set.add("BBB");
set.add("CCC");
//Set的第一种遍历方式:利用Iterator
Iterator<String> he = set.iterator();
while(he.hasNext())
{
System.out.println(he.next());
}
//Set的第一种遍历方式:利用foreach
for(String s3 : set)
{
System.out.println(s3);
}
Map的遍历方式:
/**
* Map的遍历方式
*/
Map<Integer,String> map = new HashMap<Integer,String>();
map.put(1, "xiaohong");
map.put(2, "xiaowang");
map.put(3, "xiaoli");
map.put(4, "huayaun");
map.put(5,"zhangyu");
for (Map.Entry<Integer, String> entry : map.entrySet())
{
System.out.println("Key = " + entry.getKey() + ", Value = " + entry.getValue());
}
System.out.println("map集合"+map);
/**
* 需要map中的键或者值,你可以通过keySet或values来实现遍历,而不是用entrySet。
*/
for (Integer key : map.keySet()) {
System.out.println("Key = " + key);
}
for (String value : map.values()) {
System.out.println("Value = " + value);
}
/**
* 迭代器去遍历Map
*/
Iterator<Map.Entry<Integer, String>> entries = map.entrySet().iterator();
while (entries.hasNext()) {
Map.Entry<Integer, String> entry = entries.next();
System.out.println("Key = " + entry.getKey() + ", Value = " + entry.getValue());
}
for (Integer key : map.keySet()) {
String value = map.get(key);
System.out.println("Key = " + key + ", Value = " + value);
}