List of String from List of object in java 7 [duplicate]

Question

I've a list of user object. And I want to get list of user name except using loop. Is there any collection or util function in java 7??

@Rounak: there is no way to do that without a loop. Whatever library you find, it will always use a loop. What is "huge"? — JB Nizet
– JB Nizet, Commented Nov 18, 2013 at 10:45
@JBNizet There is a way to do it without a loop, by creating a view into the underlying User list. Maybe Guava has something like that? Whether that would solve OP's performance issue highly depends on his access pattern of the name list. — Marko Topolnik
– Marko Topolnik, Commented Nov 18, 2013 at 10:50
@Rounak 5000 items in a List is a ridiculously small number. There's no performance issues involved here, trust me. — Kayaman
– Kayaman, Commented Nov 18, 2013 at 10:56

Kayaman · Accepted Answer · 2013-11-18 10:45:37Z

2

No, there's no util function. It's 3 lines of code to do it yourself.

Even if there was a util function, it wouldn't help with performance. It would be implemented as a for loop.

As for performance, have you actually profiled your application and seen that iterating the List is a performance hotspot?

answered Nov 18, 2013 at 10:45

Kayaman

73.8k6 gold badges91 silver badges128 bronze badges

Sign up to request clarification or add additional context in comments.

Comments

Peter_James · Accepted Answer · 2013-11-18 10:49:53Z

0

I think what you mean is:

for (String pos: User) {
    System.out.println(pos.toString());
}

This uses an Iterator, but since 1.5 Java you can use this shorthand to not show the Iterator.

answered Nov 18, 2013 at 10:49

Peter_James

6574 silver badges15 bronze badges