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创建包裹对象的副本

发布于 2024-12-05 06:55:08 字数 83 浏览 0 评论 0原文

我使用包裹对象将值从一个过程传递到另一个过程。我想创建包裹对象的克隆，但是如果有人知道如何创建包裹副本，请提供解决方案，我将无法使用clone（）方法。

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内心旳酸楚 2024-12-12 06:55:08

建议的解决方案不完整并且不起作用。

这是一个可行的解决方案：（

我有一个名为 MessageDescriptor 类型的对象，我想克隆它）

Parcel parcel = Parcel.obtain();
message.writeToParcel(parcel, 0);
parcel.setDataPosition(0);
MessageDescriptor messageToBeSent = MessageDescriptor.CREATOR.createFromParcel(parcel);
parcel.recycle();

The suggested solution is incomplete and will not work.

Here's a working solution:

(I have an object called message of type MessageDescriptor which I want to clone)

Parcel parcel = Parcel.obtain();
message.writeToParcel(parcel, 0);
parcel.setDataPosition(0);
MessageDescriptor messageToBeSent = MessageDescriptor.CREATOR.createFromParcel(parcel);
parcel.recycle();

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谁人与我共长歌 2024-12-12 06:55:08

假设您的对象实现了 Parcelable 接口，您应该能够执行以下操作：

SomethingParcelable myObject = new SomethingParcelable();

Parcel p = Parcel.obtain();
myObject.writeToParcel(p, 0);

//must be called after unmarshalling your data.
p.setDataPosition(0);

SomethingParcelable myClonedObject = SomethingParcelable.CREATOR.createFromParcel(p);

Assuming your object implements the Parcelable interface, you should be able to do the following:

SomethingParcelable myObject = new SomethingParcelable();

Parcel p = Parcel.obtain();
myObject.writeToParcel(p, 0);

//must be called after unmarshalling your data.
p.setDataPosition(0);

SomethingParcelable myClonedObject = SomethingParcelable.CREATOR.createFromParcel(p);

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夏见 2024-12-12 06:55:08

创建副本而无需访问对象特定创建者使用的另一种方法。

 public <T extends Parcelable> T deepClone(T objectToClone) {
    Parcel parcel = null;
    try {   
        parcel = Parcel.obtain();
        parcel.writeParcelable(objectToClone, 0);
        parcel.setDataPosition(0);
        return parcel.readParcelable(objectToClone.getClass().getClassLoader());
    } finally {
        if (parcel != null) {
            parcel.recycle();
        }
    }
}

Another way to create a copy without accessing object specific CREATOR use following generic method.

 public <T extends Parcelable> T deepClone(T objectToClone) {
    Parcel parcel = null;
    try {   
        parcel = Parcel.obtain();
        parcel.writeParcelable(objectToClone, 0);
        parcel.setDataPosition(0);
        return parcel.readParcelable(objectToClone.getClass().getClassLoader());
    } finally {
        if (parcel != null) {
            parcel.recycle();
        }
    }
}

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梦冥 2024-12-12 06:55:08

也适用于复制构造函数。

/**
 * Copy request passed in.
 *
 * @param request Request To clone, null is accepted, just creates a blank object
 */
public RealTimeJourneyPlanRequest(@Nullable RealTimeJourneyPlanRequest request) {
    if(request == null) return;
    // Only copy if the request past in is not null
    // Use the Parcel as its does deep cloning for us.
    final Parcel parcel = Parcel.obtain();
    request.writeToParcel(parcel, 0);
    parcel.setDataPosition(0);
    // Copy into this object
    readFromParcel(parcel);
    // Clean parcel back into object pool
    parcel.recycle();
}

Also useful for copy constructors.

/**
 * Copy request passed in.
 *
 * @param request Request To clone, null is accepted, just creates a blank object
 */
public RealTimeJourneyPlanRequest(@Nullable RealTimeJourneyPlanRequest request) {
    if(request == null) return;
    // Only copy if the request past in is not null
    // Use the Parcel as its does deep cloning for us.
    final Parcel parcel = Parcel.obtain();
    request.writeToParcel(parcel, 0);
    parcel.setDataPosition(0);
    // Copy into this object
    readFromParcel(parcel);
    // Clean parcel back into object pool
    parcel.recycle();
}

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