List<ArrayList<String>> compile error

[albert kao]

Please help to fix this compile error:

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

Description Resource Path Location Type
Syntax error on token "<", [ expected HwServiceImpl.java /com.mycomp.monitoring.war/src/com/mycomp/monitoring/war/service/impl line 172 Java Problem

[Janeice DelVecchio]

One (and it may be the only one, but I'm not sure) problem is you're trying to instantiate an interface(List). You should have an ArrayList or LinkedList (or another class that implements List) on the right side of the expression.

Hope that helps!
Janeice

[Siddhesh Deodhar]

.. but I'm not sure) problem is you're trying to instantiate an interface(List)

why not sure ? It is a problem . You cant instantiate interface.

[Janeice DelVecchio]

Siddhesh Deodhar wrote:

.. but I'm not sure) problem is you're trying to instantiate an interface(List)

why not sure ? It is a problem . You cant instantiate interface.

I'm just not sure if it's the ONLY problem

[albert kao]

Please help this compile error "Syntax error on token "<", [ expected".
Thanks.
List<ArrayList<String>> alerts = new ArrayList<new ArrayList<String>()>();

[pete stein]

albert kao wrote:Please help this compile error "Syntax error on token "<", [ expected".
Thanks.
List<ArrayList<String>> alerts = new ArrayList<new ArrayList<String>()>();

What Java version are you compiling with? Is it 1.5 or greater? Do you know how to check?

[Janeice DelVecchio]

So you are populating an ArrayList with ArrayLists? I had a feeling that syntax would still not work.

Uhm.... and this is really a guess.... try getting rid of the second "new." I am thinking that to populate the ArrayList of Arraylists you'll have to do something like this:

This might work:

List<ArrayList<String>> alerts = new ArrayList<ArrayList<String>>(); // note I am not instantiating the inner List here....    
List<String> foo = new ArrayList<String>(); // I instead make the inner list here 
alerts.add(foo); // and add it here

See if that works any better....

[Paul Clapham]

albert kao wrote:List<ArrayList<String>> l = new List<new ArrayList<String>()>();

Don't put garbage characters into your type names, the compiler is saying. Try this instead:

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

What that line of code creates is an ArrayList into which you can store ArrayList<String> objects. You aren't creating any ArrayList<String> objects yet so you don't need a constructor which tries to do that.

[Campbell Ritchie]

You had too many () in the first code snippet.

Rob Prime points out a better way to initialise that: like this

List<List<String>> listsOfStrings;
. . .
listsOfStrings = new ArrayList<List<String>>();

That way you can add any type of List, not being restricted to ArrayLists.