android - 发送带有 Intent 的嵌套 Parcelable

Question

我正在尝试发送一个 Parcelable 对象，该对象还包含另一个具有 Intent 的 Parcelable 对象。但是，我收到 NullPointer 异常。你能告诉我哪里做错了吗？

A.java

public class A  implements Parcelable {

    private ArrayList<B> var;

    public A()
    {
        this.var = new ArrayList<B>();  
    }

    public void addToB(B b)
    {
        var.add(b);
    }


    public ArrayList<B> getB() {
        return var;
    }

    public void setB(ArrayList<B> b) {
        this.var = b;
    }

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

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

        dest.writeTypedList(this.var);

    }

    private A (Parcel in){

        in.readTypedList(this.var, B.CREATOR);
    }

    public static final Parcelable.Creator<A> CREATOR = new Parcelable.Creator<A>() {
        public A createFromParcel(Parcel in) {
            return new A(in);
        }

        public A[] newArray(int size) {
            return new A[size];
        }
    };

}

B.java

public class B implements Parcelable  {

    private String type;


    public B(String type)
    {
        this.type=type;
    }

    public String getType() {
        return type;
    }
    public void setType(String type) {
        this.type = type;
    }


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

    @Override
    public void writeToParcel(Parcel arg0, int arg1) {
        arg0.writeString(this.type);        
    }

    private B(Parcel in) {
        this.type=in.readString();
    }

    public static final Parcelable.Creator<B> CREATOR = new Parcelable.Creator<B>() {
        public B createFromParcel(Parcel in) {
            return new B(in);
        }

        public B[] newArray(int size) {
            return new B[size];
        }
    };

}

我像这样发送带有 Intent 的 A 对象:

Intent i = new Intent(Bla.this, Blabla.class);
            i.putExtra("info", objectA);
            startActivity(i);

我收到这样的包裹:

Intent i = getIntent();
        ObjectA ci = (ObjectA)i.getParcelableExtra("info");

Answer 1

您必须在以下位置实例化您的 ArrayList< B >:

 private A (Parcel in){
    var = new ArrayList<B>();
    in.readTypedList(this.var, B.CREATOR);
}

说说它是否有效:)