I have seen many parcelable examples so far, but for some reason I can't get it to work when it gets a bit more complex. I have a Movie object, which implements Parcelable. This book object contains some properties, such as ArrayLists. Running my app results in a NullPointerException when executing the ReadTypedList ! I'm really out of ideas here
public class Movie implements Parcelable{
private int id;
private List<Review> reviews
private List<String> authors;
public Movie () {
reviews = new ArrayList<Review>();
authors = new ArrayList<String>();
}
public Movie (Parcel in) {
readFromParcel(in);
}
/* getters and setters excluded from code here */
public void writeToParcel(Parcel dest, int flags) {
dest.writeInt(id);
dest.writeList(reviews);
dest.writeStringList(authors);
}
public static final Parcelable.Creator<Movie> CREATOR = new Parcelable.Creator<Movie>() {
public MoviecreateFromParcel(Parcel source) {
return new Movie(source);
}
public Movie[] newArray(int size) {
return new Movie[size];
}
};
/*
* Constructor calls read to create object
*/
private void readFromParcel(Parcel in) {
this.id = in.readInt();
in.readTypedList(reviews, Review.CREATOR); /* NULLPOINTER HERE */
in.readStringList(authors);
}
}
The Review class:
public class Review implements Parcelable {
private int id;
private String content;
public Review() {
}
public Review(Parcel in) {
readFromParcel(in);
}
public void writeToParcel(Parcel dest, int flags) {
dest.writeInt(id);
dest.writeString(content);
}
public static final Creator<Review> CREATOR = new Creator<Review>() {
public Review createFromParcel(Parcel source) {
return new Review(source);
}
public Review[] newArray(int size) {
return new Review[size];
}
};
private void readFromParcel(Parcel in) {
this.id = in.readInt();
this.content = in.readString();
}
}
I would be very grateful if someone could just get me on the right track, I have spend quite a bit of time searching for this one !
Thanks in adnvance Wesley
reviews
and authors
are both null. You should first initialize the ArrayList. One way to do this is chain the constructor:
public Movie (Parcel in) {
this();
readFromParcel(in);
}
From the javadocs for readTypedList
:
Read into the given List items containing a particular object type that were written with
writeTypedList(List)
at the current dataPosition()
. The list must have previously been written via writeTypedList(List)
with the same object type.
You wrote them with a plain
dest.writeList(reviews);
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