Life44 :
I have a class like that:
public class WorkHelper {
private final Worker worker;
public WorkHelper(Worker worker) {
this.worker = worker;
}
//...
}
and everybody knows that the initialization below is wrong:
public class Worker {
private final WorkHelper helper;
private final SomeClass some;
public Worker(SomeClass some) {
helper = new WorkHelper(this);
this.some = some;
}
}
But how about the one below? Is this correct?
public class Worker {
private final WorkHelper helper = new WorkHelper(this);
private final SomeClass some;
public Worker(SomeClass some) {
this.some = some;
}
}
Bohemian :
All versions are unsafe; they are all cases of “letting this escape”.
Consider creating a factory method that creates the worker helper after construction is complete, for example:
public class Worker {
private WorkHelper helper;
private SomeClass some;
// hide the constructor
private Worker() {}
public static Worker create(SomeClass some) {
Worker worker = new Worker();
worker.some = some;
worker.helper = new WorkHelper(worker); // pass post construction
return worker;
}
}