If you modify a class with a final keyword, it means, this class can not be subclassed. No class can inherit the features of the final class. If you try to this, an error will result. 
Example: 
 package p1;
 public final class FinalClass{public void show(){System.out.println(\"This is a final class.\"); } }
 class FinalSub extends  FinalClass{ //errorpublic static void main(String[] args){FinalClass f=new FinalClass();f.show();}} 
 Output: The above program will result an error in compilation like \'can\'t subclassed a final class\'.
 package p1; public final class FinalClass{ public void show(){ System.out.println(\"This is a final class.\"); } } class FinalSub extends FinalClass{ //error public static void main(String[] args){ FinalClass f=new FinalClass(); f.show(); } } 

If you modify a class with a final keyword, it means, this class can not be subclassed. No class can inherit the features of the final class. If you try to this, an error will result. 
Example: 
 package p1;
 public final class FinalClass{public void show(){System.out.println(\"This is a final class.\"); } }
 class FinalSub extends  FinalClass{ //errorpublic static void main(String[] args){FinalClass f=new FinalClass();f.show();}} 
 Output: The above program will result an error in compilation like \'can\'t subclassed a final class\'.
 package p1; public final class FinalClass{ public void show(){ System.out.println(\"This is a final class.\"); } } class FinalSub extends FinalClass{ //error public static void main(String[] args){ FinalClass f=new FinalClass(); f.show(); } }