Dependency inversion principle

DIP.java

// Bad example
class Worker {
    public void work() {// ....working}
}

class Manager {
    Worker worker;
    public void setWorker(Worker w) {worker = w;}
    public void manage() {worker.work();}
}
class SuperWorker {
    public void work() {//.... working much more}
}

// Good example
interface IWorker {
    public void work();
}

class Worker implements IWorker{
    public void work() {// ....working}
}

class SuperWorker  implements IWorker{
    public void work() {//.... working much more}
}

class Manager {
    IWorker worker;
    public void setWorker(IWorker w) {worker = w;}
    public void manage() {worker.work();}
}