Autocomplete for generic types in Eclipse

Question

"Refer to objects by their interfaces" is a good practise, as mentioned in Effective Java. So for example i prefer

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

over

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

in my code. One annoying thing is that if i type ArrayList<String> al = new and then hit Ctrl+Space in Eclipse i get ArrayList<String>() as propostal. But if i type List al = new and then hit Ctrl+Space i will get only propostal to define anonymous inner class, but not propostals such as new ArrayList<String>(), what is 99% the case, or for example new Vector<String>().

Question: Is there any way to get the subclasses as propostals for generic types?

Would it be too cheeky to suggest "Use Guava and `Lists.newArrayList()`? — Jon Skeet, Jul 03 '12 at 14:59
of course it is good, but actually i want to get all subclasses as propostal, not only for lists. — AvrDragon, Jul 03 '12 at 15:01
@JonSkeet You would add a new dependency (I mean you mgiht want to add it anyway, but assume not) just to change `new ArrayList<>()` to `Lists.newArrayList()`? — Tom Hawtin - tackline, Jul 03 '12 at 15:26
To be sure, I'm not sure I would want to start _any_ Java project without Guava as a dependency already... — Louis Wasserman, Jul 03 '12 at 15:42

score 9 · Accepted Answer · answered Jul 03 '12 at 15:12

9

I would suggest simply writing the expression first and then hitting Ctrl+2, L. Then you can name the variable, followed by Enter, Down, Enter. Done.

answered Jul 03 '12 at 15:12

Ben Schulz

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But it looks like that fills in the variable type as `ArrayList` instead of `List` for example (so you get the same result). – Paul Bellora Jul 03 '12 at 17:13
@PaulBellora: You missed the key sequence, which selects the second suggestion in the list of suggested types for the variable. And that should be List, where ArrayList would be the first. – Bananeweizen Jul 03 '12 at 17:43

score 2 · Answer 2 · answered Jul 03 '12 at 17:59

Depending on your personal style of writing such code, this is an alternative inspired by the answer of @Ben Schulz. If you typically write the assignment first like

al = new ArrayList<String>();

then you can use Ctrl+1 to start the "Create local variable" quick fix. Hitting Tab will now directly open the type selection where you select the List type.

score 2 · Answer 3 · answered Aug 28 '13 at 07:58

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JDK 1.7 doesn't need to specify the generic type at the right of the equal. Preference -> Java -> Compiler to 1.6

answered Aug 28 '13 at 07:58

user2724466

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Autocomplete for generic types in Eclipse

3 Answers3