extent and implementation of class in JAVA
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extent and implementation of class in JAVA
extends is for extending a class.
implements is for implementing an interface
The difference between an interface and a regular class is that in an interface you can only specify methods.
Also java doesn't support multiple inheritance for classes. This is solved by using multiple interfaces
public interface Inter{
public void do();
public String doThis(int number);
}
public class sub implements Inter{
public void do(){
//specify what must happen
}
public String doThis(int number){
//specfiy what must happen
}
}
now extending a class
public class SuperClass{
public int getNb(){
//specify what must happen
return 1;
}
public int getNb2(){
//specify what must happen
return 2;
}
}
public class SubClass extends SuperClass{
//you can override the implementation
@Override
public int getNb2(){
return 3;
}
}
in this case
Subclass s = new SubClass();
s.getNb(); //returns 1
s.getNb2(); //returns 3
SuperClass sup = new SuperClass();
sup.getNb(); //returns 1
sup.getNb2(); //returns 2
implements is for implementing an interface
The difference between an interface and a regular class is that in an interface you can only specify methods.
Also java doesn't support multiple inheritance for classes. This is solved by using multiple interfaces
public interface Inter{
public void do();
public String doThis(int number);
}
public class sub implements Inter{
public void do(){
//specify what must happen
}
public String doThis(int number){
//specfiy what must happen
}
}
now extending a class
public class SuperClass{
public int getNb(){
//specify what must happen
return 1;
}
public int getNb2(){
//specify what must happen
return 2;
}
}
public class SubClass extends SuperClass{
//you can override the implementation
@Override
public int getNb2(){
return 3;
}
}
in this case
Subclass s = new SubClass();
s.getNb(); //returns 1
s.getNb2(); //returns 3
SuperClass sup = new SuperClass();
sup.getNb(); //returns 1
sup.getNb2(); //returns 2
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