How to make a constructor of a generic type

Question

given the the below code,how can i make the constructor of a generic type so that it can accept any class passed to it

code:

ServiceCtrl(Context ctx, Class<SPPService> sppServiceClass) {
    this.mCtx = ctx;
    this.mClass = sppServiceClass;
}

public boolean isMyServiceRunning() {
    ActivityManager manager = (ActivityManager) this.mCtx.getSystemService(this.mCtx.ACTIVITY_SERVICE);
    for (ActivityManager.RunningServiceInfo service : manager.getRunningServices(Integer.MAX_VALUE)) {
        if (this.mClass.getName().equals(service.service.getClassName())) {
            return true;
        }
    }
    return false;
}

@Flown would u please provide an example because when i used ? android studion underscores the 2nd line in the constructor with red — Amrmsmb, Dec 21 '15 at 08:37
@user2121 : did you change the declaration of `mClass` member as well ? — Gaël J, Dec 21 '15 at 08:39

Gaël J · Answer 1 · 2015-12-21T08:46:34.480

1

Do you mean, make sppServiceClass generic in the constructor ?

If so, you're looking for this :

ServiceCtrl(Context ctx, Class<?> clazz) {
    ...
}

EDIT : you need to change the declaration of mClass as well to Class<?>.

edited Dec 21 '15 at 08:46

answered Dec 21 '15 at 08:37

Gaël J

11,274
4
17
32

Berkay Turancı · Accepted Answer · 2015-12-21T08:41:01.010

1

public class ServiceCtrl<E extends Object> {
    private Class<E> mClass;

    ServiceCtrl(Context ctx, Class<E> sppServiceClass) {
        this.mCtx = ctx;
        this.mClass = sppServiceClass;
    }

    public boolean isMyServiceRunning() {
        ActivityManager manager = (ActivityManager) this.mCtx.getSystemService(this.mCtx.ACTIVITY_SERVICE);
        for (ActivityManager.RunningServiceInfo service : manager.getRunningServices(Integer.MAX_VALUE)) {
            if (this.mClass.getName().equals(service.service.getClassName())) {
                return true;
            }
        }
        return false;
    }
}

edited Dec 21 '15 at 08:41

answered Dec 21 '15 at 08:38

Berkay Turancı

3,373
4
32
45

@user2121 add `` to your class definition, as I edited – Berkay Turancı Dec 21 '15 at 08:41
would u please tell me the difference between E and "?" ? – Amrmsmb Dec 21 '15 at 08:43

How to make a constructor of a generic type

2 Answers2