Collections in Java better programming practice

I see something similar in most java code that uses collections

List<String> list = new ArrayList<String>();

But I always wonder why it is more popular

ArrayList<String> = new ArrayList<String>();

I studied it, but I can't understand much

Solution

Because when using objects through its interface, you can change the implementation later For example:

public ArrayList<String> doSomething(..) {
    ...
    return arrayList;
}

But after a while, it seems that ArrayList is most commonly used by callers of this method is inefficient, so you decide to change it to LinkedList

>If your method returns only list, you are done > if your method returns ArrayList, you should go to all places where the method is called and change it What if someone uses some ArrayList - specific method - you have to think about how to refactor it This is a good plan If your code is a library and other branches / companies are using it, you may encounter inefficient code

You can also see:

> What does it mean to “program to an interface”? > “Program to an interface”. What does it mean?