CODEWITHSUNDEEP
javaandroidparcelable
FET
FET

Reputation: 942

How to implement the write & read in Parcelable Class

Parcelable

I have this Player Class:

public class Player implements Parcelable {
private String mName; // Player's name
private Card mCard; // Player's current card
private boolean mLifeStatus = true; // Player's life status
private boolean mProtected = false; // If the Player's been protected by the guard or not
private int mId; // ID of the Player
private int mCount;

/* everything below here is for implementing Parcelable */

// 99.9% of the time you can just ignore this
@Override
public int describeContents() {
    return 0;
}

// write your object's data to the passed-in Parcel
@Override
public void writeToParcel(Parcel out, int flags) {
    out.writeString(mName);
    out.writeValue(mCard);
    out.writeValue(mLifeStatus);
    out.writeValue(mProtected);
    out.writeInt(mId);
    out.writeInt(mCount);
}

// this is used to regenerate your object. All Parcelables must have a CREATOR that implements these two methods
public static final Parcelable.Creator<Player> CREATOR = new Parcelable.Creator<Player>() {
    public Player createFromParcel(Parcel in) {
        return new Player(in);
    }

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

// example constructor that takes a Parcel and gives you an object populated with it's values
private Player(Parcel in) {
    mName = in.readString();
    mCard = in.readValue();
    mLifeStatus = in.readValue(mLifeStatus);
    mProtected = in.readValue(mProtected);
    mId = in.readInt();
    mCount = in.readInt();
}
}

I've tried to fill the last constructor by myself, but I don't know how to read the value of booleans and of custom classes, just like my Card class, which is the Class for the mValue mCard.

I tried to use this but still didn't work: mCard = in.readValue(Card.class.getClassLoader);

How should I write these two methods in order to make the Class implement Parcelable how it's supposed to be?

Upvotes: 0

Views: 1856

Answers (3)

OneCricketeer
OneCricketeer

Reputation: 191738

To write the card 

out.writeParcelable(mCard, flags);

To read the card 

mCard = (Card) in.readParcelable(Card.class.getClassLoader());

To write the Boolean

out.writeInt(mLifeStatus ? 1 : 0);
out.writeInt(mProtected ? 1 : 0);

To read the Boolean

mLifeStatus = in.readInt() == 1;
mProtected = in.readInt() == 1;

(This is how writeValue and readValue work internally for Boolean types)

Upvotes: 4

Dale Wilson
Dale Wilson

Reputation: 9434

A Parcel can store primitive types and Parcelable objects. That implies that anything stored in the Parcel must either be a primitive type or a Parceelable object.

Looking at the member data of Player, I see a bunch of primitive types and one more complex type: Card.

To store a Card in your Parcel, you must make the Card class Parcelable.

Alternatively if the Player class has access to the internal details of Card you can write code to pull the primitive types out of Card and store them, then on the read side, pull the primitive types out of the Parcel and use them to construct a Card. This technique only works if Card is simple enough that you don't worry about violating encapsulation.

Upvotes: 3

JunYu Zhou
JunYu Zhou

Reputation: 33

writeToParcel:

dest.writeByte((byte) (myBoolean ? 1 : 0));

readFromParcel:

myBoolean = in.readByte() != 0;

ref: https://stackoverflow.com/a/7089687/4577267

Upvotes: -1

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