Interface as a type!

[guro]

I have a question about java interface. Assume that:
public interface intf_X{
// abstract methods define
}

Since intf_X can be used as a type (e.g. intf_X x1;) can we use intf_X as a return type from a function (I mean: intf_X foo()) and in which case we can use it? Can you give a simple example?

Thanks

[Fubarable]

the best test is already in your hands: your friendly Java compiler!

Why not create a simple interface and see if you can return it from a method? See if it compiles?

[Sylar]

Agree ^

Its best if you discover it first hand.

[guro]

Hello all,
I did the following test and gain a bit understanding of interface. It compiles just fine.

public interface X_intf{
void X_method();
}

public class X_impl{
// Constructor
public X_impl(){
// Do something
}

void X_method(){
// Do something
}
}

public interface MyInterface{
X_intf getInfo();
}

public class MyClass implements MyInterface(){
X_intf x;

// Constructor
public MyClass(X_intf x){
this.x = x;
}

public X_intf getInfo(){
return x;
}
}

// in Main.java
X_impl x_var = new X_impl();
MyClass var1 = new MyClass(x);

System.out.println(var1.getInfo().X_method());

[toadaly]

Yes. Interfaces can be used everywhere classes can be used (well, except that interfaces obviously have no constructors, and a few other restrictions!).

Therein lies the power of an interface.