I have some questions regarding which overloaded method will be called in certain cases.
Case 1:
public void someMethod(Object obj){
System.out.println("Object");
}
public void someMethod(InputStream is){
System.out.println("InputStream");
}
public void someMethod(FilterInputStream fis){
System.out.println("FilterInputStream");
}
I know that if I pass it String, it will print “Object”. However, if I pass it an InputStream? It gets more confusing if I pass it something like BufferedInputStream. Will it be a call to Object One, InputStream one or FilterInputStream one? Does the order mean that the methods matter?
Case 2:
This is a little trickier because it takes advantage of multiple interface inheritance. Neither BlockingQueue nor Deque are sub / supertypes of each other, but both are supertypes of BlockingDeque. Sun has added multiple inheritance with interfaces because they don't need a tree structure. An ad for BlockingDeque is this
public interface BlockingDeque extends BlockingQueue, Deque {.
public void someMethod(BlockingQueue bq){
System.out.println("BlockingQueue");
}
public void someMethod(Deque bq){
System.out.println("Deque");
}
public void someCaller(){
BlockingDeque bd = new LinkedBlockingDeque();
someMethod(bd);
}
Will this call someMethod (BlockingQueue) or someMethod (Deque)?
Case 3:
You can combine these two with this:
public void someMethod(Queue q){
}
public void someMethod(Deque q){
}
public void someMethod(List p){
}
public void someCaller(){
someMethod(new LinkedList());
}
Same question: someMethod (Queue), someMethod (Deque) or someMethod (List)?
Case 4:
You can also make things very complex by introducing two arguments:
public void someMethod(Collection c1, List c2){
}
public void someMethod(List c1, Collection c2){
}
public void someCaller(){
someMethod(new ArrayList(), new ArrayList());
}
Will this call someMethod (Collection, List) or vice versa?
Case 5:
It gets worse when they have different return types:
public Class<?> someMethod(BlockingQueue bq){
return BlockingQueue.class;
}
public String someMethod(Deque bq){
return "Deque";
}
public void someCaller(){
BlockingDeque bd = new LinkedBlockingDeque();
System.out.println(someMethod(bd));
}
. - ? someMethod (BlockingQueue).toString() someMethod (Deque)?