The difference between Java collections and arrays

Both collections and containers are containers in Java.

The difference between

Array features: fixed size, can only store data of the same data type

Collection features: The size can be dynamically expanded, can store various types of data

conversion

Array to collection:

Arrays. asList (array)

Example:

int[] arr = {1,3,4,6,6};
Arrays.asList(arr);
for(int i=0;i<arr.length;i++){
  System.out.println(arr[i]);
}　　

Collection converted to an array:

Collection. toArray ();

Example:

List list = new ArrayList();
list.add("a");
list.add("b"); 
list.toArray();
System.out.println(list.toString());