Java HashMap: getKey(), getValue(), and get() methods
KW.java
importjava.util.HashMap;classKW{publicstaticvoidmain(String[]args){//HashMap class implements the Map interfaceHashMap<Long,String>hm=newHashMap<>();hm.put(25622348989L,"James Moore");hm.put(25622348990L,"Donald Taylor");hm.put(25622348991L,"Edward Parkar");hm.put(25622348992L,"Ryan Bakshi");for(HashMap.Entrym:hm.entrySet()){System.out.println("Account No: "+m.getKey()+" Name: "+m.getValue());}System.out.println(hm.get(25622348992L));}}
Output
kodingwindow@kw:~$ javac KW.java kodingwindow@kw:~$ java KW
Account No: 25622348992 Name: Ryan Bakshi
Account No: 25622348991 Name: Edward Parkar
Account No: 25622348990 Name: Donald Taylor
Account No: 25622348989 Name: James Moore
Ryan Bakshi
kodingwindow@kw:~$
kodingwindow@kw:~$ javac KW.java kodingwindow@kw:~$ java KW
[25622348992, 25622348991, 25622348990, 25622348989]
[Ryan Bakshi, Edward Parkar, Donald Taylor, James Moore]
kodingwindow@kw:~$
Java HashMap: replace() method
KW.java
importjava.util.HashMap;classKW{publicstaticvoidmain(String[]args){//HashMap class implements the Map interfaceHashMap<Long,String>hm=newHashMap<>();hm.put(25622348989L,"James Moore");hm.put(25622348990L,"Donald Taylor");hm.put(25622348991L,"Edward Parkar");hm.put(25622348992L,"Ryan Bakshi");System.out.println(hm);hm.replace(25622348991L,"Edward D Parkar");hm.replace(25622348992L,"Ryan Bakshi","Ryan S Bakshi");System.out.println(hm);}}
importjava.util.HashMap;classKW{publicstaticvoidmain(String[]args){//HashMap class implements the Map interfaceHashMap<Long,String>hm1=newHashMap<>();hm1.put(25622348989L,"James Moore");hm1.put(25622348990L,"Donald Taylor");HashMap<Long,String>hm2=newHashMap<>();hm2.put(25622348991L,"Edward Parkar");hm2.put(25622348992L,"Ryan Bakshi");hm2.putIfAbsent(25622348993L,"Marie Peters");hm2.putAll(hm1);for(HashMap.Entrym:hm2.entrySet()){System.out.println("Account No: "+m.getKey()+" Name: "+m.getValue());}}}
Output
kodingwindow@kw:~$ javac KW.java kodingwindow@kw:~$ java KW
Account No: 25622348993 Name: Marie Peters
Account No: 25622348992 Name: Ryan Bakshi
Account No: 25622348991 Name: Edward Parkar
Account No: 25622348990 Name: Donald Taylor
Account No: 25622348989 Name: James Moore
kodingwindow@kw:~$
Java HashMap: remove() and clear() methods
KW.java
importjava.util.HashMap;classKW{publicstaticvoidmain(String[]args){//HashMap class implements the Map interfaceHashMap<Long,String>hm=newHashMap<>();hm.put(25622348989L,"James Moore");hm.put(25622348990L,"Donald Taylor");hm.put(25622348991L,"Edward Parkar");hm.put(25622348992L,"Ryan Bakshi");hm.remove(25622348992L);hm.remove(25622348991L,"Edward Parkar");System.out.println(hm);hm.clear();if(hm.isEmpty()){System.out.println("Map is empty now");}}}
Output
kodingwindow@kw:~$ javac KW.java kodingwindow@kw:~$ java KW
{25622348990=Donald Taylor, 25622348989=James Moore}
Map is empty now
kodingwindow@kw:~$
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