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);
        }

Answer 1

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]