Eclipse compile error shown incorrectly (Can only iterate over an array or an instance of java.lang.Iterable)

Question

I'm experiencing a really weird issue in Eclipse (Photon 4.8). I have some code that uses the for (Object x : ObjectList){} logic and all of a sudden it's throwing a compile error on me.

Can only iterate over an array or an instance of java.lang.Iterable

So as to keep it super simple, I wrote the following as a test in my class

ArrayList<String> tmp = new ArrayList<String>();
tmp.add("making sure there's something here");
tmp.add("and again...just for the heck of it");
for(String x : tmp) {
    System.out.println(x);
}

That block also throws the same error (on the "tmp" object). I've restarted Eclipse several times and done a clean/rebuild. My Java compiler is set to 1.8 which is a change that i made about a week ago from 1.6. But it's been compiling fine the past week with no errors. Just saw this pop up today out of the blue.

Seems like a bug in the Eclipse compiler, but I'm not sure how to resolve it. Any help would be greatly appreciated.

Adding "Minimal, Complete and Verifiable Example" below

public class Test { 
    public static void main(String[] args) {
        java.util.ArrayList<String> tmp = new java.util.ArrayList<String>();
        tmp.add("String 1");
        tmp.add("String 2");
        for(String x : tmp) {
            System.out.println(x);
        }
    }
}

The above class throws the following compile error for "tmp"

Can only iterate over an array or an instance of java.lang.Iterable

Why blame Eclipse or Java? Please understand that 99.99% the bug is yours, and it's always best to start out assuming that this is so — Hovercraft Full Of Eels, Feb 18 '19 at 13:51
You may use `tmp.forEach(System.out::println)` (since Java 8). — Ole V.V., Feb 18 '19 at 13:55
Ugh..my bad on having the Iterator it in there. I edited that out (in my post above and in my code). It's throwing the same error even against an ArrayList object which does implement the Iterable interface. — Jason Schade, Feb 18 '19 at 14:10
I added a screenshot to my original post showing that the compile error is being reported on an ArrayList object (which again, implements Iterable...through List, Collection....) — Jason Schade, Feb 18 '19 at 14:22
You need to create and post a valid [mcve] to prove that this is not a duplicate question. Also, you don't have your own class named `ArrayList` nearby do you? — Hovercraft Full Of Eels, Feb 18 '19 at 14:27
I cannot reproduce. In my Eclipse your program runs nicely and prints `String 1` and `String 2` (I only get “Redundant specification of type arguments ”, but that’s only a warning and doesn’t affect running the program). — Ole V.V., Feb 19 '19 at 08:17

Alan Kavanagh · Answer 1 · 2019-02-18T13:50:43.157

2

You don't need to define a new iterator:

ArrayList<String> tmp = new ArrayList<String>();
tmp.add("making sure there's something here");
tmp.add("and again...just for the heck of it");
for(String x : tmp) {
    System.out.println(x);
}

>> making sure there's something here
>> and again...just for the heck of it

edited Feb 18 '19 at 13:50

answered Feb 18 '19 at 13:48

Alan Kavanagh

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Yes, that is what I initially did. That is now throwing a compile error in Eclipse. Hence my thinking that there's some kind of bug. – Jason Schade Feb 18 '19 at 14:17

Eclipse compile error shown incorrectly (Can only iterate over an array or an instance of java.lang.Iterable)

1 Answers1