android - 在 Android Parcelable 类中读写长对象

Question

如果说我有一个长对象跟随。以下示例是否演示了读写 Long 对象的正确方法？

Class MyClass implements Parcelable {
   private Long aLongObject;

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

    @Override
    public MyClass[] newArray(int size) {
       .....
    }
};


protected MyClass(Parcel in) {// reading Parcel
    super(in);

  aLongObject = in.readLong(); // correct way to ready Long object?
 }

   @Override
public void writeToParcel(@NonNull Parcel dest, int flags) {
    super.writeToParcel(dest, flags);

      dest.writeLong(aLongObject); // is this correct way to send Long?
  }
}

Answer 1

您的方法的问题是 Long 值可能是 null 但 Parcel 方法只获取/返回原始数据的值输入long，查看documentation了解详情。因此，您需要一种变通方法来存储 Long 值。

我喜欢用一个int来表示我的Long值是否为null(你只能存储boolean 数组没有单个 boolean 值)和一个 long 来存储数值(如果不是的话):

写入包裹

int indicator = (aLongObject == null) ? 0 : 1;
long number = (aLongObject == null) ? 0 : aLongObject;
dest.writeInt(indicator); 
dest.writeLong(number); 

读取包裹

// NOTE: reading must be in the same order as writing
Long aLongObject;
int indicator = in.readInt();
long number = in.readLong();
if(indicator == 0){
    aLongObject = null;
}
else{
    aLongObject = number;
}