How to remove integer from list?

Question

I need to remove integer from integer arraylist. I have no problem with strings and other objects. But when i removing, integer is treated as an index instead of object.

List<Integer> list = new ArrayList<Integer>();
list.add(1);
list.add(2);
list.add(300);
list.remove(300);

When I am trying to remove 300 i am getting: 06-11 06:05:48.576: E/AndroidRuntime(856): java.lang.IndexOutOfBoundsException: Invalid index 300, size is 3

`list.remove(300);` here 300 treated as primitive `int`, pass `Integer` Object. — Subhrajyoti Majumder, Jun 11 '13 at 06:16

score 29 · Accepted Answer · answered Jun 11 '13 at 06:14

This is normal, there are two versions of the .remove() method for lists: one which takes an integer as an argument and removes the entry at this index, the other which takes a generic type as an argument (which, at runtime, is an Object) and removes it from the list.

And the lookup mechanism for methods always picks the more specific method first...

You need to:

list.remove(Integer.valueOf(300));

in order to call the correct version of .remove().

score 11 · Answer 2 · answered Jun 11 '13 at 06:14

11

Use indexof to find the index of the item.

list.remove(list.indexOf(300));

answered Jun 11 '13 at 06:14

SBI

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While this does work, it will be much more expensive to execute than using `Integer.valueOf` to simply get an object. – ApproachingDarknessFish Jun 11 '13 at 06:16
It absolutely will ;) – SBI Jun 11 '13 at 06:17
Why is this getting upvoted when it clearly is not the right way to do it? – assylias Jun 11 '13 at 06:23
That's SO for you. It's seemingly not wrong enough. – SBI Jun 11 '13 at 06:26

score 5 · Answer 3 · answered Jun 11 '13 at 06:14

5

Try (passing an Integer, object, instead of an int, primitive) -

list.remove(Integer.valueOf(300));

to invoke the right method - List.remove(Object o)

answered Jun 11 '13 at 06:14

Bhesh Gurung

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Pritesh Shah · Answer 4 · 2013-06-12T05:34:18.830

Please try below code to remove integer from list,

public static void main(String[] args) {
        List<Integer> lIntegers = new ArrayList<Integer>();
        lIntegers.add(1);
        lIntegers.add(2);
        lIntegers.add(300);
        lIntegers.remove(new Integer(300));
        System.out.println("TestClass.main()"+lIntegers);
}

If you remove item by passing primitive then it will take it as index and not value/object

score 1 · Answer 5 · answered Jun 11 '13 at 06:15

1

Use list.remove((Integer)300);

answered Jun 11 '13 at 06:15

Sanjaya Liyanage

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I did test it.And worked fine with no errors.please explain why this is wrong – Sanjaya Liyanage Jun 11 '13 at 06:19
My apologies, I guessed this would not work but apparently autoboxing is slightly more overzealous than I suspected. You are correct; there is no problem. – ApproachingDarknessFish Jun 11 '13 at 06:22
@ValekHalfHeart thanks. I thought kind of my answer might not a good practice when it was down voting. – Sanjaya Liyanage Jun 11 '13 at 06:24
+1 Casting to integer is equivalent to Integer.valueOf. – assylias Jun 11 '13 at 06:25

How to remove integer from list?

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