Help me Please..

[polymorphism]

Hi all,

public interface ActionListener{
public actionPerformed(ActionEvent e);
}

According above code the heading of the JButton method to associate itself with an ActionListener is

public void addActionListener(ActionListener aListener);

So, Why was the parameter aListener chosen to be of an interface
type in this header?


I think that because the parameter aListener its type interface.

What do you think??

[JavaBean]

Because we want to be able to use any class which implements ActionListener as an action listener. This way, user can easily define his/her own ActionListener by implementing this interface and can add it to any component.

[sha_5552002]

Hi am shankar.

y the out object of printstream is defined inside system class?

[JavaBean]

It is just the standard output stream. You can use output stream of a socket or sth else as output stream too.

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