comparing between two arraylists and remove extra element from there

Question

how do I compare two arraylists?

I have a sdCoverList array and thumbnailList array.

02-04 11:05:05.210: I/System.out(4035): HASHED THUMBNAIL[-2122410790, 2043473787, 1914391068, 1785308349, 1656225630, 1527142911, 1398060192, 1268977473, 1139894754, 1010812035, 1242943301, 1113860582, 984777863, 855695144, 726612425, 597529706, 468446987, 339364268, 210281549]
02-04 11:05:05.210: I/System.out(4035): SD COVER LIST[-2122410790, 2043473787, 1914391068, 1785308349, 1268977473, 1656225630, 1527142911, 1139894754, 1398060192, 1010812035, 1242943301, 1113860582, 984777863, 855695144, 726612425, 597529706, 468446987, 339364268, 210281549, 717409028]

In my sd cover list, i have an extra value that i want to remove away but first i'd have to compare with thumbnailList array first. if both have the same elements, don't do anything but if theres an extra, remove it from sd card.

My array lists

for sdCoverList:

// CHECK DIRECTORY BEFORE DELETING THEM
            File strPath = new File(Environment.getExternalStorageDirectory() + folderName+"/Covers");
            File yourDir = new File(strPath, "");
            if(yourDir.length()!=0)
            for (File f : yourDir.listFiles()) {
                if (f.isFile())
                {
                    String name = f.getName();
                    sdCoverList.add(name);
                    //System.out.println(sdCoverList);
                }

for hashedthumbnail

for (int a=0;a<=thumbnailList.size()-1;a++)
        {
            String hashed = String.valueOf(thumbnailList.get(a).hashCode());
            Log.d("hashed",hashed);
            hashedThumbnail.add(hashed);
        }

a nice answer is [here](http://stackoverflow.com/a/919420/1265724) — Ram kiran Pachigolla, Feb 04 '13 at 03:12
if i already have an arraylist, how do i use collection with it? — user1234555, Feb 04 '13 at 03:19

score 9 · Accepted Answer · answered Feb 04 '13 at 03:39

List<String> sdCoverList = new ArrayList<String>();
sdCoverList.add("-2122410790");
sdCoverList.add("2043473787");
sdCoverList.add("717409028");

List<String> hashedThumbnail = new ArrayList<String>();
hashedThumbnail.add("-2122410790");
hashedThumbnail.add("2043473787");

System.out.println("sdCover List: " + sdCoverList);
System.out.println("hashedThumbnail List: " + hashedThumbnail);


List<String> temp = new ArrayList<String>();
temp.addAll(sdCoverList);
temp.removeAll(hashedThumbnail);

System.out.println("temp List: " + temp);

sdCoverList.removeAll(temp);

System.out.println("sdCover List: " + sdCoverList);

The output will be

sdCover List: [-2122410790, 2043473787, 717409028]
hashedThumbnail List: [-2122410790, 2043473787]
temp List: [717409028]
sdCover List: [-2122410790, 2043473787]

i have more then 50000 records in array if i am tring to addAll and removeAll Application Stuck in that case what i do?? — Ravi Makvana, Mar 31 '15 at 12:41

comparing between two arraylists and remove extra element from there

1 Answers1