how to change items in a list of string in java8

问题

I want to change all items in list.
What is the correct way to do it with java8?

public class TestIt {

public static void main(String[] args) {
    ArrayList<String> l = new ArrayList<>();
    l.add("AB");
    l.add("A");
    l.add("AA");
    l.forEach(x -> x = "b" + x);
    System.out.println(l);
}

}

回答1:

You can use replaceAll.

Replaces each element of this list with the result of applying the operator to that element.

ArrayList<String> l = new ArrayList<>(Arrays.asList("AB","A","AA"));
l.replaceAll(x -> "b" + x);
System.out.println(l);

Output:

[bAB, bA, bAA]

回答2:

If you want to use streams, you can do something like that:

List<String> l = new ArrayList<>(Arrays.asList("AB","A","AA"));
l = l.stream().map(x -> "b" + x).collect(Collectors.toList());
System.out.println(l);

Output:

[bAB, bA, bAA]

Of course it is better to use replaceAll if you want to change all elements of a list but using streams enables you to also apply filters or to parallel easily. replaceAll also modifies the list and throws an exception when the list is unmodifiable, whereas collectcreates a new list.

来源：https://stackoverflow.com/questions/22757764/how-to-change-items-in-a-list-of-string-in-java8