可分块对象中的数组列表 [英] Arraylist in parcelable object

问题描述

到目前为止，我已经看到了许多可分割的示例，但由于某种原因，当它变得更复杂时，我无法让它工作.我有一个 Movie 对象，它实现了 Parcelable.这个 book 对象包含一些属性，比如 ArrayLists.执行 ReadTypedList 时，运行我的应用程序会导致 NullPointerException ！我真的没有想法了

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);
   }
}

复习课:

    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();
   }

}

如果有人能让我走上正轨，我将不胜感激，我花了很多时间来寻找这个！

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 !

提前致谢韦斯利

推荐答案

reviews 和 authors 都为 null.您应该首先初始化 ArrayList.一种方法是链接构造函数:

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); 
}

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