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I Have an ArrayList<String> that I use to store PackageInfo(an example of an element in the arraylist is "com.skype.raider").

The arralist is initialized as follows:

 private List<String> pkgs;

And In The Class Consturctor

 pkgs = new ArrayList<>();

When i invoke pkgs.remove(String), it doesn't work, but when i repeatedly try and remove, it eventually works.

Heres how i test if removal worked( i edited the code so it reads more easily)

private void togglePackage(String selectedPackage,CheckBox chk_app){ String m_pkg = selectedPackage.toString(); //redundant .toString() boolean checked = !chk_app.isChecked(); //checkbox boolean toggle if (checked && !pkgs.contains(m_pkg)) { //if not already in arraylist pkgs.add(m_pkg); //adding the newly checked package } else if (!checked && pkgs.contains(m_pkg)) { //if it needs to be removed pkgs.remove(m_pkg); //<-----------------------This works around the 3rd time i press the checkbox } //Here i check if the string was actually removed from the arrylist //This following code will not be in production, i just used it for testing if (pkgs.contains(m_pkg)) { if (checked) { chk_app.setChecked(checked);//Success } else { chk_app.setChecked(!checked);//Failure } } else { if (!checked) { chk_app.setChecked(checked);//Success } else { chk_app.setChecked(!checked);//Failure } } }

Here is the unedited onclick event

RelativeLayout rl_container = (RelativeLayout) child.findViewById(R.id.rl_container); rl_container.setTag(pkg); rl_container.setOnClickListener(new View.OnClickListener() { @Override public void onClick(View v) { String m_pkg = v.getTag().toString(); System.out.println("Pkg = "+m_pkg); boolean checked = !chk_app.isChecked(); if (checked && !pkgs.contains(m_pkg)) { pkgs.add(m_pkg); System.out.println("Adding " + m_pkg); } else if (!checked && pkgs.contains(m_pkg)) { pkgs.remove(m_pkg); System.out.println("Removing " + m_pkg); } if (pkgs.contains(m_pkg)) { if (checked) { System.out.println("Success"); chk_app.setChecked(checked); } else { System.out.println("Fail"); chk_app.setChecked(!checked); } } else { if (!checked) { System.out.println("Success"); chk_app.setChecked(checked); } else { System.out.println("Fail"); chk_app.setChecked(!checked); } } } });

As an example i have included the arraylists contents that i got by iterating over the list. as well as the log output of my tests

List contents:

com.sbg.mobile.phone com.google.android.youtube com.e8tracks com.vlingo.midas com.google.android.googlequicksearchbox com.truecaller

Logcat output from unedited code when i try to deselect "com.sbg.mobile.phone" 

12-18 10:37:25 ViewPostImeInputStage ACTION_DOWN 12-18 10:37:25 Pkg = com.sbg.mobile.phone 12-18 10:37:25 Removing com.sbg.mobile.phone 12-18 10:37:25 Fail 12-18 10:37:28 ViewPostImeInputStage ACTION_DOWN 12-18 10:37:28 Pkg = com.sbg.mobile.phone 12-18 10:37:28 Removing com.sbg.mobile.phone 12-18 10:37:28 Fail 12-18 10:37:30 ViewPostImeInputStage ACTION_DOWN 12-18 10:37:31 Pkg = com.sbg.mobile.phone 12-18 10:37:31 Removing com.sbg.mobile.phone 12-18 10:37:31 Fail 12-18 10:37:32 ViewPostImeInputStage ACTION_DOWN 12-18 10:37:32 Pkg = com.sbg.mobile.phone 12-18 10:37:32 Removing com.sbg.mobile.phone 12-18 10:37:32 Fail 12-18 10:37:33 ViewPostImeInputStage ACTION_DOWN 12-18 10:37:33 Pkg = com.sbg.mobile.phone 12-18 10:37:33 Removing com.sbg.mobile.phone 12-18 10:37:33 Success

PS. This is my first question, so be gentle. I would also appreciate any advice on how to improve on asking questions ,I tried to include all of the required info, but if you need anything else, please let me know.

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5
  • are you sure your ArrayList contains the given string the first times you try to remove it? Commented Dec 18, 2015 at 9:04
  • int position = pkgs .indexOf("yourtext"); then pkgs .remove(position ); Commented Dec 18, 2015 at 9:05
  • 1
    do not understand why you use "isChecked" to verify if the String is still in the arry... you should use only pkgs.contains(...) and nothing else really matter. Commented Dec 18, 2015 at 9:06
  • @mithrop I dont really use isChecked to verify that it is still in the arraylist, i only used it to measure success or failure in the context of what i was trying to achieve. Commented Dec 18, 2015 at 9:19
  • @koutuk I tried using position, but it seems that didnt solve it, using a HashSet instead worked Commented Dec 18, 2015 at 9:20

3 Answers 3

Reset to default
6

I think it might be a problem, because ArrayList gives you an opportunity to store equal objects multiple times. Maybe, it is a good idea to use HashSet<String> instead?

 private Set<String> pkgs;
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2 Comments

Thanks for your answer, Ill give it a go and get back to you
Thank you @RexSplode, This was the problem.
2

Let's consider ArrayList default behaviour:

ArrayList of strings have 5 elements. If you remove element at 2nd position then arraylist will become set of 4 elements and 3rd element now at 2nd position. Now when you remove 5th element but its position is changed now.

So use Arraylist of hashmap and when you want to remove elements from arraylist, you should iterate all elements of arraylist and remove particular element from it.

OR if you want only checked items when some event (like button press) occers then get only that checked items from adapter of list.

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1 Comment

Thank you for your answer @S.K, I did consider this, but it turns out it was another problem, see the accepted answer
1

Problem is in your condition. Condition should be like:

 if (checked) { if (!pkgs.contains(m_pkg)) { pkgs.add(m_pkg); } } else { if (pkgs.contains(m_pkg)) { pkgs.remove(m_pkg); } }

you can refer to the links:

Adding/Removing Strings in an ArrayList<String> by Checkbox

How to Handle the checkbox ischecked and unchecked event in android

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1 Comment

Thank you for your answer, Logically the two conditions are the same, the issue wasnt that the condtion failed, it was an issue with the container i used, But your condition is better formatted and i have changed mine to use yours.

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