ArrayList
ArrayList<Object> arr = new ArrayList<>();
for(Object o : arr){
// todo......
}
Collection
Collection<Object> arr = new Collection<>();
for(Object o : arr){
// todo......
}
HashMap
方法1:(集合遍历)
HashMap<Integer, Product> map = new HashMap<>();
Set<Map.Entry<Integer, Product>> entries = map.entrySet();
for (Map.Entry<Integer, Product> entry : entries) {
// entry.getValue()
// entry.getKey()
// entry是kv集合,可以获取key,value
}
方法2:(值遍历)
HashMap<Integer, Product> map = new HashMap<>();
Collection<Object> values = map.values();
for (Object o: values ) {
// 只是遍历map里面的值,忽略key
}
Set
方法1:
Set<String> set = new Set<>();
for(String s : set){
// todo
}
方法2:(迭代器遍历)
Set<String> set = new Set<>();
Iterator iterator = set.iterator();
while (iterator.hasNext()) {
System.out.println(iterator.next());
}