Is there an interface similar to Callable but with arguments?
Since Java 8 there is a whole set of Function-like interfaces in the java.util.function
package. The one you're asking for specifically is simply Function
.
Prior to Java 8, there was no general-purpose, built-in interface for this, but some libraries provided it.
For example Guava has the Function<F,T>
interface with the method T apply(F input)
. It also makes heavy use of that interface in several places.
at first it thought that this is done with an interface but then i found that it should be done using an abstract class.
i have solved it this way:
edit: lately i just use this:
public static abstract class callback1<T>{
public abstract void run(T value);
}
public static abstract class callback2<T,J>{
public abstract void run(T value,J value2);
}
public static abstract class callback3<T,J,Z>{
public abstract void run(T value,J value2,Z value3);
}
public static abstract class callbackret1<R,T>{
public abstract R run(T value);
}
public static abstract class callbackret2<R,T,J>{
public abstract R run(T value,J value2);
}
public static abstract class callbackret3<R,T,J,Z>{
public abstract R run(T value,J value2,Z value3);
}
CallBack.java
public abstract class CallBack<TRet,TArg> {
public abstract TRet call(TArg val);
}
define method:
class Sample2
{
CallBack<Void,String> cb;
void callcb(CallBack<Void,String> CB)
{
cb=CB; //save the callback
cb.call("yes!"); // call the callback
}
}
use method:
sample2.callcb(new CallBack<Void,String>(){
@Override
public Void call(String val) {
// TODO Auto-generated method stub
return null;
}
});
two arguments sample: CallBack2.java
public abstract class CallBack2<TRet,TArg1,TArg2> {
public abstract TRet call(TArg1 val1,TArg2 val2);
}
notice that when you use Void return type you have to use return null; so here is a variation to fix that because usually callbacks do not return any value.
void as return type: SimpleCallBack.java
public abstract class SimpleCallBack<TArg> {
public abstract void call(TArg val);
}
void as return type 2 args: SimpleCallBack2.java
public abstract class SimpleCallBack<TArg1,TArg2> {
public abstract void call(TArg1 val1,TArg2 val2);
}
interface is not useful for this.
interfaces allow multiple types match same type. by having a shared predefined set of functions.
abstract classes allow empty functions inside them to be completed later. at extending or instantiation.