interface Incrementable
{
void increment();
}
//very simple to just implemets the interface;
class Callee1 implements Incrementable
{
private int i = 0;
public void increment()
{
i++;
System.out.println(i);
}
}
class MyIncrement
{
public void increment()
{
System.out.println("Other operation");
}
static void f(MyIncrement mi )
{
mi.increment();
}
}
// If your class must implements increment() in
// some other way, you must use an inner class:
class Callee2 extends MyIncrement
{
private int i = 0;
public void increment()
{
super.increment();
i++;
System.out.println(i);
}
private class Closure implements Incrementable
{
public void increment()
{
Callee2.this.increment();
}
}
Incrementable getCallbackReference()
{
return new Closure();
}
}
class Caller
{
private Incrementable callbackReference;
Caller(Incrementable cbh)
{
callbackReference = cbh;
}
void go()
{
callbackReference.increment();
}
}
public class Callbacks
{
public static void main(String args[])
{
Callee1 c1 = new Callee1();
Callee2 c2 = new Callee2();
MyIncrement.f(c2);
Caller caller1 = new Caller(c1);
Caller caller2 = new Caller(c2.getCallbackReference());
caller1.go();
caller1.go();
caller2.go();
caller2.go();
}
}
输出 Other operation
1
1
2
Other operation
2
Other operation
3