如何使我的自定义对象可打包? [英] How can I make my custom objects Parcelable?

问题描述

我正在尝试使我的对象可打包.但是，我有自定义对象，并且这些对象具有我创建的其他自定义对象的 ArrayList 属性.

I'm trying to make my objects Parcelable. However, I have custom objects and those objects have ArrayList attributes of other custom objects I have made.

最好的方法是什么?

推荐答案

你可以找到一些这样的例子 这里，此处(代码取自此处) 和 这里.

You can find some examples of this here, here (code is taken here), and here.

您可以为此创建一个 POJO 类，但您需要添加一些额外的代码以使其成为 Parcelable.看看实现.

You can create a POJO class for this, but you need to add some extra code to make it Parcelable. Have a look at the implementation.

public class Student implements Parcelable{
        private String id;
        private String name;
        private String grade;

        // Constructor
        public Student(String id, String name, String grade){
            this.id = id;
            this.name = name;
            this.grade = grade;
       }
       // Getter and setter methods
       .........
       .........

       // Parcelling part
       public Student(Parcel in){
           String[] data = new String[3];

           in.readStringArray(data);
           // the order needs to be the same as in writeToParcel() method
           this.id = data[0];
           this.name = data[1];
           this.grade = data[2];
       }

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

       @Override
       public void writeToParcel(Parcel dest, int flags) {
           dest.writeStringArray(new String[] {this.id,
                                               this.name,
                                               this.grade});
       }
       public static final Parcelable.Creator CREATOR = new Parcelable.Creator() {
           public Student createFromParcel(Parcel in) {
               return new Student(in); 
           }

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

一旦你创建了这个类，你就可以像这样通过Intent轻松地传递这个类的对象，并在目标活动中恢复这个对象.

Once you have created this class, you can easily pass objects of this class through the Intent like this, and recover this object in the target activity.

intent.putExtra("student", new Student("1","Mike","6"));

在这里，student 是您从包中解包数据所需的密钥.

Here, the student is the key which you would require to unparcel the data from the bundle.

Bundle data = getIntent().getExtras();
Student student = (Student) data.getParcelable("student");

此示例仅显示 String 类型.但是，您可以打包所需的任何类型的数据.试试看.

This example shows only String types. But, you can parcel any kind of data you want. Try it out.

示例stackoverflow.com/users/738438/rukmal-dias">Rukmal Dias.

Another example, suggested by Rukmal Dias.

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