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  1. #1
    guro is offline Member
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    Default Interface as a type!

    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

  2. #2
    Fubarable's Avatar
    Fubarable is offline Moderator
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    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?

  3. #3
    Sylar's Avatar
    Sylar is offline Member
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    Agree ^

    Its best if you discover it first hand.

  4. #4
    guro is offline Member
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    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());

  5. #5
    toadaly is offline Senior Member
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    Default

    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.

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