How I can convert this Generic Class to a Parcelable?

Question

I want to convert this generic class to a parcelable object, but I don't have very clear the concepts of the issue.

Class:

public class Type<T> implements Parcelable {

    // T stands for "Type"
    private T t;

    public void set(T t) { this.t = t; }

    public T get() { return t; }

}

This is what I've tried,. but I know that this is not correct, or maybe this is not complete.

public class Type<T> implements Parcelable {

    // T stands for "Type"
    private T t;

    protected Type(Parcel in) {
    }

    public void set(T t) { this.t = t; }

    public T get() { return t; }

    @Override
    public int describeContents() {
        return 0;
    }

    @Override
    public void writeToParcel(Parcel dest, int flags) {
    }

    public static final Creator< Type > CREATOR = new Creator< Type >() {
        @Override
        public Type createFromParcel(Parcel in) {
            return new Type(in);
        }

        @Override
        public Type[] newArray(int size) {
            return new Type[size];
        }
    };

}

score 2 · Answer 1 · answered Jan 24 '18 at 16:36

This is similar approach as vikas kumar but guarantte that you can pass only Parcelable as T parameter so you avoid exception.

public class Type<T extends Parcelable> implements Parcelable {
    private T t;

    protected Type(Parcel in) {
        t = (T) in.readValue(t.getClass().getClassLoader());
    }

    public static final Creator<Type> CREATOR = new Creator<Type>() {
        @Override
        public Type createFromParcel(Parcel in) {
            return new Type(in);
        }

        @Override
        public Type[] newArray(int size) {
            return new Type[size];
        }
    };

    @Override
    public int describeContents() {
        return 0;
    }

    @Override
    public void writeToParcel(Parcel dest, int flags) {
        dest.writeValue(t);
    }
}

vikas kumar · Answer 2 · 2018-01-24T16:55:17.287

1

Your generic data type may cause runtime error

so make sure you implements Parcelable and also the class you are passing should implement Parcelable otherwise it will cause runtime error.

     public class Type<T extends Parcelable> implements Parcelable {

    // T stands for "Type"
    private T t;

    public void set(T t) { this.t = t; }

    public T get() { return t; }


    protected Type(Parcel in) {
        final String className = in.readString();
        try {
            t = in.readParcelable(Class.forName(className).getClassLoader());
        } catch (ClassNotFoundException e) {
            Log.e("readParcelable", className, e);
        }
    }

    @Override
    public int describeContents() {
        return 0;
    }

    @Override
    public void writeToParcel(Parcel dest, int flags) {
        dest.writeValue(t);
    }

    @SuppressWarnings("unused")
    public static final Parcelable.Creator<Type> CREATOR = new Parcelable.Creator<Type>() {
        @Override
        public Type createFromParcel(Parcel in) {
            return new Type(in);
        }

        @Override
        public Type[] newArray(int size) {
            return new Type[size];
        }
    };
}

edited Jan 24 '18 at 16:55

answered Jan 24 '18 at 16:27

vikas kumar

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Thank you, I was using a Andorid Parcelable Generator but with private T t, there were errors. – Víctor Martín Jan 24 '18 at 16:29
t = (T) in.readValue(T.class.getClassLoader()); is warning me with an error. I don't know how to fix it :D – Víctor Martín Jan 24 '18 at 16:31
Works. How I can use it? – Víctor Martín Jan 24 '18 at 17:03
just create Type obj = new Type(); – vikas kumar Jan 24 '18 at 17:07
But I need to reference this on a method like: public void method_x(Type typeObject{}) But I get an error saying that T is not defined. – Víctor Martín Jan 24 '18 at 17:24

How I can convert this Generic Class to a Parcelable?

2 Answers2