What are the difference between "if(map.get(key)-map1.getOrDefault(key, 0)!=0)" and "if(map.get(key)!=map1.getOrDefault(key, 0))"

Question

I have the following code-

package DP.permutation_in_string;

import java.util.HashMap;
import java.util.Map;

public class LeetCode {
    public static boolean checkInclusion(String s1, String s2) {
        Map<Character, Integer> map = new HashMap<>();
        
        for(int i=0; i<s1.length(); i++){
            map.put(s1.charAt(i), map.getOrDefault(s1.charAt(i), 0)+1);
        }

        for(int i=0; i<=s2.length()-s1.length(); i++){
                Map<Character, Integer> map1 = new HashMap<>();
         
                for(int j=i; j<i+s1.length();j++){
                    map1.put(s2.charAt(j), map1.getOrDefault(s2.charAt(j),0)+1);
                }
                
                if(mapCompare(map, map1))
                    return true;
        }
        
        return false;
    }
    
    static boolean mapCompare(Map<Character, Integer> map, Map<Character, Integer> map1){
        for(char key:map.keySet())
            //if(map.get(key)!=map1.getOrDefault(key, 0))
            if(map.get(key)-map1.getOrDefault(key, 0)!=0)
                return false;
        
        return true;
    }
    public static void main(String[] args) {
        String s1="ckzviabspcfbabslodcxtzanlsnwbqrozvnfadhtskosxhxaxzwcthvirwivsfuyxgkdvvdmmaoohvnfegkzdajhzibfiuxvsihpseyyiapmgldyojfselzzudzrxcksvfoqoeimyfhnvidryqhhpvjawwpzspcfnvmewnhcbbbwfjifmcuspbrrjyhcusyiuydscwenyicdlfzaoaiudsdyjmhmzwmeaozheiaddevjrrgsfgqnyeoyxfvktctazsfizkynlookeorzmdvtloyfpbqjgzhjvykdthwkuubnbalrddjxpizysaptrinlytecouekkpsfzbjaitckodcdinydtaaakbntwbvrcabylllxtgtkdqfkjggvbrnxnvcsfpcutabvazyeqzitpwhhdpcxaklhbjrcsqzveytzbgoeqnyrbkvkfnlqhrnedjomfmkuadwabnzomgvtdypocbvipryedcxnrcrqwpefqducxxilhpoewlliilidxucjydpahcumngpekrlroftwpbaejfjmohnkulxdglcpcszpyqestonhxskshzmdkikjkeymddyiysmigvqjveocbabhcofwyseytwfgiqmufcqrugwofytxzwwwiwlxdshtamwneosotqbfjjdxmhjkmzcvpmkuumycqzvlmwvjdwkcikyewupwaotrseyomhuykdkohveftgqfoqjcnstlxdasnvimslmuqsqrhvbukyfvpswmlavtxegbcesxgzswwnslxymmrdwmpalcazukvyyotlvwvlishtgbmlznrmcjysjemwqfjgbehnowgjlvtgemlkkdqpxiuqwhqkqdkexoflxfescoblknurkntbpfqfiervqgeiasguycmjoyzyujgzdfjobrswjpxixmadnnkdtazbasmnnlbubokkvomtupdpqwnoddummmqbwbthfhqdgdawdwxlmgvelhefvqcrpxbkgvhyrpxmfivrvkkqfpxjhzqesiqoeanqzpvbgonwptzqgtajoiiphivxtefarwjyoklkxumrndswebdsgiipzrcunpnibmxwlkihnzlswaujflztxxnuhojrpkzldwhnuiizxalawskkvaplopthvzjrbqfwpwjfkzrhyciajdsaeusctnvajuubjiqdqsaqjxtxgxabpdwxzgiedyyeosfdbkairekywkilyksjratftctphompqoomxucysbzrpywjzumoiizklkooilgeapimiixawfgiszfqucihxfrtrwijyeiebudncwnxbnafohhhqaltksafjfegxlbbewetsyrtuxxlngffpcnyfdarqwznsuiuhvqshjpvbiqkxgfwyrkdlorlwgexfinunbfzifxlfufalbkyfdekhupuuflsetpbppaahwbtjpjguygpnavimbbaeikwjxurdxyfgmldgdbkyxzhvwlxzlpnpmzlyosvhngmuqkrvcsabhiahhguxuakphuaptbjfpxybqnlfazkagwlbvzcnzorpymafiwvtkjtilwihwoyelogtpdyipzkurqcghpdqgrfpnmrmahbkbyupxwooblaydongjrlnuhoikoyiexgzlzgonceyhfwypsgypilxcnkdhxvbfddnhvdicolrjyzttrymmcvoyswaszbbugsuuewhewtoxgnrbfqsysjqqcutoikssesxaohxxfxofiguvpgzfkimmqdjuyljlpndapzygidopwxnaetmmpyaqozybbpfqlonebiilvckmtyaommksfcrmdeyjjbjncmpruofaaccnvndkovjugcrzcwkbdhqdiwnvnavnngloshyataygyukrecamzftmeephucmofjgrzsexsprpdkazhmtaepqppgzjmxxzlpbkouqlhqcxdpaslrjrsnfbjvbekpyqsldzhxarpzbbjteudfwfjdipgcdwylorxivwbjkegazpcngzkokygjfnmfeumbetznsxsmyhccurqdzznvhrtawpklrrrbedqzkiczignlaoaiydezgktdecaxwxxecymbuisvhlcjlhmnpjuegnaawfxopvvkxihehquxzlveabigomeptsqbfurytjikpbtsotgfghadilylnimxcsvgtmzjgxjyhabtfawzmomctquctwnolglflghdugeutgdmkitunbkhgoceqyrzvwprotiysaiqcnwxflcjgjqobeskizjqqwihnmxyvbeeufyvouupnyuuyauxtmhtqlbgoacjdkvmuqohbkpctfwxvwlghevsuozrgxkrrrllnvjloeligxvnvzluxlajszgeilxdjaviawhlthtxuclqypgdiwgwrhynmzqghyzeednlmyepgxxvtmjsuprisbgyvcojhculwdkjmpmvueaftiujrmdqptrmlrwdyjtjlznuhftzmffbcqsjemrpjrqxtuxhlnqvckgcuvhswgtxonfljjwnexdafpjzwjdypdfwhwogikkpsvuckmgehcqmdecriamdqsdsxuhsdqenrpifzjnpvrbpvetatbmvsncltabzspzedumeclbxiqnsmdkbqfedikoalfsnxkhewwzyeqxlecfimvdpxdnvrtlxlxzakupknvchursvilyjyfxmvdeojclhjjwxtpqiogsfdnzchrlztvxmibbociiberaevpjmyqxvcicxuwkmyjlgxhvrjdqbjzdctzwidoplkvazhgsdbkavmrpfjgebydmloykqtxocdhcpwrtvawhofvwnohtwodppmcrbhvrvexzijiwgkptntyljvikjlzpjvpxaejfwzyldxrckbzylvhpqmjjeyatmrbcgozvcalcctngwuysjqmkmhjwmyyfxhdjswimahqzptrphtjekkabpgopfdnhwaclxzavftmswadgztxceonrkczurtdvxhabiafyzdbdbyorerekjzgpueihiamlscdndjjgqwdjsmeweqrfpypfrfsciclvrrqchnmtxscbvbbipzingkeopuvlnpqaeqidlpvusbkjhntvxbookqctymjmhqjvsnaiblmnofxphanpxspmkmxmyejooqpytdixgguonbpaipurpwwfqxrrtekvvtpgndabbvjcoxonxciuypxqcfolxirvafnmgsrcrenwyuxfekuqyfdtvhvmonvkstbmvygsbguiknltpixsebxktczniurulxpyxckrtmhpvgqpbvlqwvcqwaocalqtdwomgrjyvryodeikbeeebcrrkugliqgktoohsneynmfafykpmndfgwtpdwfrmicenyntbfyyntlqqrujfioycrhopgiadmsjcycucyuqvzufbvachmlwyfxspzrvkkvkhuykoqrwshzmyypmvosuezpsgtqtecayj";
        String s2="livsugnixbcmmajhinduvzfjzxtzneixibupxfezifaovcbowfayjtlcdsjogjytuczxbwluiktkdyecquebuvkgfobhpiqfbyckfbchvfkdowckrvuiblhbmubugrrovdhbyvevwetlusthiyxgtaqcdfytgbkrnnjifdslzntgnryqcmwkumdvqctymyffanmawobfihsfqmtqvivvouunsexpzcfmiituppwxgjyspyoeuspyystyneoonatbojiufzhhfeakqzeypaopkyscadbkzsnnjewgflysazhwaigicrzeccanemfmrvrdzxtcbuqvjblrynlhbmtkzhtiqnhrfclxovtijwucgvsreirqmhweoazxdyydksrchvizmljhdkekaxbqkleaolqnepijxpwbcxfadfsxswhzmmffsmoiyfosbwjjcgqpexddwizaiqpsaagwxkajdhqeyouihwlfrmnelakembxwcrvwqyaguvqewjczfmfqiqmjbqxcmfrpqoewszkomwckfgrlkannjefxsulbpkpxlvbrgwruvhdonuezoomvnyridrosfzhfvhmqbzdsfvjgfdqvafheuhveaqwrofhgkfobkkevdsqyumzrvapfjypvjsdzaxxwcnsbxasqewmkmucxbgjqntdsvrbndebttkoiznatcjgtgklljurkkdvpbrtbolvgrqwsnuoubhgvtmbakwgvxypndpqtireuvbdxfjcioqqsbfrqahqsfbwfnlkwobnqdbptxrizourrxyjejflgkbcwmrtttqeeqkyzrzdcfakwcfajhjfmcpnsbekwtzgpbwrotgsxopaemsnywoxsqxoyricgosfurfggulchgyoocivnkqytgbroijmaduoywbudtgwugekikebdadoygtmikcficifdcsvritesbvznlbrgbveudwzatarhbehowrrakimocgqyxzedhlqxzxtqloupbwbdvewcbehkmoahoykouhilivtxukqhwmyjjqmfxqybahsubfvnhctudtpxwsnwfmsamavjkqiabzzcqgqssygswavqpdtxfyognqybsogsbkzkktfjqebhitvqnawokacbkfkthqoammdscyvxgaaqyaplexhlwweambfwtylvihpdedshaeluxgthrejkgkvwrtyzpuygqghtlkmpnzkyjiwyuaqijkxttvdsxddfkmgnnlmamjumsbjmjxqkrgncrwyoyetdsmtanoasirkfklcsxukfdebnlbgobwgyqrthzwjbwpxuxmheplqyjaucgrptfewjahejsfypktnpafmlrzekbjqsgthrwbdxttitsqyglsjgnzmscncgvkooxdlxsmmugeeayicndgoagpfckerzuwdphqksijniyckzviabspcfbabslodcxtzanlsnwbqrozvnfadhtskosxhxaxzwcthvirwivsfuyxgkdvvdmmaoohvnfegkzdajhzibfiuxvsihpseyyiapmgldyojfselzzudzrxcksvfoqoeimyfhnvidryqhhpvjawwpzspcfnvmewnhcbbbwfjifmcuspbrrjyhcusyiuydscwenyicdlfznoaiudsdyjmcmzwmeaozheiaddevjrrgsfgqnyeoyxfvktctazsfizkynlookeorzmdvtloyfpbqjgzhjvykdthwkuubnbalrddjxpihysaptrinlytecouekkpsfzbjaitckodcdinydtaaakbntwbvrcasylllxtgtkdqfkjggvbanxnvcsfphutabvazyeqzitpwhhdpcxaklhbjrcsqzveytzbgoeqnyrbkvkfnlqhrnedjomfmkuadwabnzomgvtdypocbvipryedcxnrcrqwpefqducxxilhpoewlliilidxucjydpahcumagpekrlroftwpbaejfjmohnkulxdglcpcszpyqestonhxskshzmdkikjkeymdfyiysmigvqjveocbabhcofwyseytwfgiqmufcqrugwofytxzwwwiwlxdshtamwneosotqbfjjdxmhjkmzcvpmkuumycqzvlmwvjdwkcityewupwaotrseyomhuykdkohveftgqfoqjcnstlxdasnvimslmuqsqrhvbukyfvpswmlavtxegbcesxgzswwnslxymmrdwmpalcazukvyyotlvwvlishtgbmlznrmcjysjemwqfjgbehnowgjlvtgemlkkdqpxiuqwhqkqdkexoflxfescoblknurkntbpfqfiervqgeiesguycmjoyzyujgzdfjobrswjpxixmadnnkdtazbasmnnlbubokkvomtupdpqwnoddummmqbwbthfhqdgdawdwxlmgvelhefvqcrpxbkgvhyrpxmfivrvkkqfpxjhzqesiqoeanqzpvbgonwptzqgtajoiiphivxtefarwjyoklkxumrndswebdsghipzrcunpnibmxwlkihnzlswaujflztxxnuhojrpkzldwhnuiizxalawskkvaplopthvzjrbqfwpwjfkzrhyciajdsaeusctnvajuubjiqdqsaqjxtxgxabpdwxzgiedyyeosfdbkrirekywkilyksjratftctphompqoomxucysbzrpywjzumoiizklkooilgeapimiixawfgiszfqucihxfrtrwijyeiebudncwnxbnafohhhqaltksafjfegxlbbewetsyrtuxxlngffpcnyfdarqwznsuiuhvqshjpvbiqkxgfwyrkdlorlwgexfinunbfzifxlfufalbkyddekhupuuflsetpbppaahwbkjpjguygpnavimbbaeikwjxurdxyfgmldgdbkyxzhvwlxzlpnpmzlyosvhngmuqkrvcsabhiahhguxuakphuaptbjfpxybqnlfazkagwlbvzcnzorpymafiwvtkjtilwihwoyelogtpdyipzkurqcghpdqgrfpnmrmahbkbyupxwooblaydongjrlnuhoikoyiexgzlzgonceyhfwypsgypilxcnkdhxvbfddnhvdicolrjyzttrymmcvoyswaszbbugsuuewhawtoxgnrbfqsysjqqcutoikssesxaohxxfxofiguvpgzfkimmqdjuyljlpndapzygidopwxnaetmmpyaqozybbpfqlonebiilvckmtyaommksfcrmdeyjjbjncmpruofaaccnvndkovjugcrzcwkbdhqdiwnvnavnngloshyataygyukrecamzftmeephucmofjgrzsepsprpdkazhmtaepqppgzjmxxzlpbkouqlhqcxdpaslrjrsnfbjvbekpyqsldzhxarpzbbjteudfwfjdipgcdwylorxivwbjkegazpcngzkokygjfnmfeumbetznsxsmyhccurqdzznvhrtawpklrrrbedqzkiczignlaoaiydezgktdecaxwxxecymbuisvhlcjlhmnpjuegnaawfxopvvkxihehquxzlveabigomeptsqbfurytjikpbtsotgfghadilylnimxcsvgtmzjgxjyhabtfawzmomctquctwnolglflghdugeutgdmkitunbkhgoceqyrzvwprotiysaiqcnwnflcjgjqobeskizjqqwihnmxyvbeeufyvouupnyuuyauxtmhtqlbgoacjdkvmuqohbkpctfwxvwlgievsuozrgxkrrrllnvjloeligxvnvzluxlajszgeilxdjaviawhlthtxuclqypgdiwgwrhynmzqghyzeednlmyepgxxvtmjsuprisbgyvcojhculwdkjmpmvueaftiujrmdqptrmlrwdyjtjlznuhftzmffbcqsjemrpjrqxtuxhlnqvckgcuvhswgtxonfljjwnexdafpjzwjdypdfwhwogikkpsvuckmgehcqmdecriamdqsdsxuhsdqenrpifzjnpvrbpvetatbmvsncltabzspzedumeclbxiqnsmdkbqfedikoalfsnxkhewwzyeqxlecfimvdpxdnvrtlxlxzakupknvchursvilyjyfxmvdfojclhjjwxtpqiogsfdxzczrlztvxmibbociiberaevpjmyqxvcicxuwkmyjlgxhvrjdqbjzdctzwidoplkvazhgsdbkavmrpfjgebydmloykqtxocdhcpwrtvawhofvwnohtwodxpmcrbhvrvexzijiwgkptntyljvikjlzpjvpxaejfwzyldxrckbzylvhpqmjjeyatmrbcgozvcalcctngwuysjqmkmhjwmyyfxhdjswimahqzptrphtjekkabpgopfdnhwaclxzavftmswadgztxceonrkczurtdvxhabiafyzdbdbyorerekjzgpueihiamlscdndjjgqwdjsmeweqrfpypfrfsciclvrrqchnmtxscbvbbipzingkeopuvlnpqaeqidlpvusbkjhntvxbookqctymjmhqjvsnaiblmnofxphanpxspmkmxmyejooqpytdixgguonbpaipurpwwfqxrrtekvvtpgndabbvjcoxonxciuypxqcfolxirvafnmgsrcrenwyuxeekuqyfdtvhvmonvkbtbmvygsbguiknltpixsebxktczniurulxpyxckrtmhpvgqpbvlqwvcqwaocalqtdwomgrjyvryodeikbeeebcrrkugliqgktoohsneynmfafykpmndfgwtpdwfrmicenyntbfyyntlqqrujfioycrhopgiadmsjcycucyuqvzufbvachmlwyfxspzrvkkvkhuykoqrwshzmyypmvosuezpsgtqtecayjdasrysrmdewxmqntqmuavczczrcrzokjzqtiucdfmijfqkizfftxsddkdwlofkjbuhzodgzeslpezdifpdfktufgekrrbsxfeqduphoemwhncbblqkoyychuwlkjfxjmvdasfhwxnxjmstabgiujditpmpnojsfzpgqvupkdipphutiewfynvoxmdaloyxsksaxnyyizreshgejskhokarxddrrkoeglwledovrbarhkfcetrshiuucmbrtqjawsavbhuoijshkzcmogbjurybhwduushlmhjzgthhlvftpytayjzzbcxbtvozwhsmtkltgrugyfaoldnnswbohpsqvwbwtjcxeewsvfwpkwltxmomlwsylwvcmmrwjvvbbktqxnypfmhjigzaqacmprjfnooinkgbjzzwyuafxsmqdcmsxhbfoejjzxizufvfejrrcfaijqovlxdngkgwisvryevivawbcttftuxympktxbxotvdycxhfokmtdeqacdceffvhvjpnzfuhqslixvlcxehvbkritokoqqlbmkdkgflthhhdgiaidjjpvcatctiosolfqzcjmdppttztpklgosnshspna";
        System.out.println(checkInclusion(s1, s2));
    }

}

Using if(map.get(key)-map1.getOrDefault(key, 0)!=0) works correctly but not if(map.get(key)!=map1.getOrDefault(key, 0)). What is the reason behind this?

Answer 1

Maps store reference-typed keys and values. Your maps store Integers.

map.get(key) is an Integer, as is map1.getOrDefault(key, 0). If you compare them using !=, you are comparing the references for identity; that is, are they the same instance. For example, new Integer(0) == new Integer(0) is false, even though they are both instances of Integer that wrap the int 0.

However, if you subtract two Integers, they are unboxed, because of binary numeric promotion. new Integer(0) - new Integer(0) == 0, because each new Integer(0) is unboxed to 0, and 0 - 0 == 0.

You would have got the same answer if you had used !A.equals(B) instead of A != B, because this compares by (in)equality, rather than identity. For example:

if(!map.get(key).equals(map1.getOrDefault(key, 0)))

Alternatively, you could have used Integer.compare:

if(Integer.compare(map.get(key), map1.getOrDefault(key, 0)) != 0)

or explicit unboxing:

if(map.get(key).intValue() != map1.getOrDefault(key, 0).intValue())