implementing Parcelable in android, onRestoreInstanceState is not getting called

Question

Following is my class:

public class Line implements Parcelable {
    private Point start, end;

    public Line() {
        // TODO Auto-generated constructor stub
    }

    public Line(Point start, Point end) {
        this.end = end;
        this.start = start;
    }

    public Point getStart() {
        return start;
    }

    public void setStart(Point start) {
        this.start = start;
    }

    public Point getEnd() {
        return end;
    }

    public void setEnd(Point end) {
        this.end = end;
    } 
    @Override
public void writeToParcel(Parcel dest, int flags) {
    // TODO Auto-generated method stub

}
}

it contains two Point(android.graphics.Point) objects and i would like to implement parcelable in it, so that I can restore ArrayList of Line objects in Activity.

The problem as both my attributes are of type Point not sure how to write it in writeToParcel and read it in

public Line(Parcel in) {
        super();

    }

EDIT

following the answer I implemented the Line class. But in activity the problem is onRestoreInstanceState is never getting called.

When I press home button, and get back to the app all the data in my arrayLists is lost.

    @Override
public void onSaveInstanceState(Bundle savedInstanceState) {
    super.onSaveInstanceState(savedInstanceState);
    // Save UI state changes to the savedInstanceState.
    // This bundle will be passed to onCreate if the process is
    // killed and restarted.
    savedInstanceState.putInt("player", player);
    savedInstanceState.putParcelableArrayList("lines", lines);
    savedInstanceState.putParcelableArrayList("rects1", rects1);
    savedInstanceState.putParcelableArrayList("rects2", rects2);
    // etc.
}

@Override
public void onRestoreInstanceState(Bundle savedInstanceState) {
    super.onRestoreInstanceState(savedInstanceState);
    // Restore UI state from the savedInstanceState.
    // This bundle has also been passed to onCreate.
    player = savedInstanceState.getInt("player");
    lines = savedInstanceState.getParcelableArrayList("lines");
    rects1 = savedInstanceState.getParcelableArrayList("rects1");
    rects2 = savedInstanceState.getParcelableArrayList("rects2");
}

`Point` already implements the Parcelable interface, so you can call `WriteToParcel()` on the points. Just make sure you read them out of a parcel in the same order as you wrote them to the parcel. — ThaMe90, Jan 23 '14 at 07:38
I am not sure how to read and write these objects to Parcel. — vipul mittal, Jan 23 '14 at 07:38

Gopal Gopi · Accepted Answer · 2014-01-23T07:48:13.953

1

try this...

public class Line implements Parcelable {
    private Point start, end;

    public Line() {
    }

    public Line(Point start, Point end) {
        this.end = end;
        this.start = start;
    }

    public Point getStart() {
        return start;
    }

    public void setStart(Point start) {
        this.start = start;
    }

    public Point getEnd() {
        return end;
    }

    public void setEnd(Point end) {
        this.end = end;
    }

    @Override
    public void writeToParcel(Parcel dest, int flags) {
        dest.writeParcelable(start, flags);
        dest.writeParcelable(end, flags);
    }

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

    public static final Parcelable.Creator<Line> CREATOR = new Parcelable.Creator<Line>() {

        @Override
        public Line createFromParcel(Parcel source) {
            Line line = new Line();
            Point start = source.readParcelable(Point.class.getClassLoader());
            Point end = source.readParcelable(Point.class.getClassLoader());
            line.setStart(start);
            line.setEnd(end);
            return line;
        }

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

edited Jan 23 '14 at 07:48

answered Jan 23 '14 at 07:40

Gopal Gopi

11,101
1
30
43

Wouldn't you need to pass the classloader for the `Point` class into the `source.readparcelable()` function? As you are reading out a `Point`, and not a `Line`. – ThaMe90 Jan 23 '14 at 07:43
@ThaMe90 here we can pass even `null` also. see the documentation `A ClassLoader from which to instantiate the Parcelable object, or null for the default class loader` – Gopal Gopi Jan 23 '14 at 07:45
@Gopal Line class is not showing any error and I guess is save as well but the problem now is that on reStore is not getting call see my question again. – vipul mittal Jan 23 '14 at 07:52
@vipulmittal `onRestoreInstanceState()` will be called only when you are changing the orientation. it will be not called when you press home button – Gopal Gopi Jan 23 '14 at 07:55
so how to preserve my arraylists as when i press home come back to my app lists are empty – vipul mittal Jan 23 '14 at 08:19
When you come back from the homescreen, the application goes trough the `onResume()` method (see [this](http://developer.android.com/reference/android/app/Activity.html#ActivityLifecycle)). – ThaMe90 Jan 23 '14 at 08:30
@vipulmittal have you seen ThaMe90's comment? – Gopal Gopi Jan 23 '14 at 09:06

score 0 · Answer 2 · edited May 23 '17 at 11:56

0

Use My Answer. you need to write all the values in writeToParcel method. and create one Constructor and perform below steps.

edited May 23 '17 at 11:56

Community

1
1

answered Jan 23 '14 at 08:30

Imtiyaz Khalani

2,037
18
32

implementing Parcelable in android, onRestoreInstanceState is not getting called

2 Answers2