Android中的Activity之间传递自定义类型的List的方法

一、传递自定义类型
当Activity之间进行通信时，我们通常会遇到传递自定义类型，正如我们所知，自定义类型是无法直接通过Android中的Intent进行传递的，这时，我们可以采取将自定义类型实现Parcelable接口，并使用Intent的putExtras来进行传递。

以下是本人的一个数据类的实例：

public class UserData implements Parcelable{    private String username;    private String password;    private String Email;    private boolean logined;    public UserData() {        this.username = "";        this.password = "";        this.Email = "";        this.logined = false;    }    @Override    public void writeToParcel(Parcel dest, int flags) {        dest.writeString(username);        dest.writeString(password);        dest.writeString(Email);    }    public UserData(String username, String password, String Email) {        this.username = username;        this.password = password;        this.Email = "";        this.logined = false;    }    public UserData(Parcel in) {        username = in.readString();        password = in.readString();        Email = in.readString();    }    public static final Creator CREATOR = new Creator() {        @Override        public UserData createFromParcel(Parcel in) {            return new UserData(in);        }        @Override        public UserData[] newArray(int size) {            return new UserData[size];        }    };    @Override    public int describeContents() {        return 0;    }    public String getUsername() {        return this.username;    }    public String getPassword() {        return this.password;    }    public void setLoginStatus(boolean status) {        this.logined = status;    }    public boolean isLogined() {        return this.logined;    }    public void setUsername( String username ) {        this.username = username;    }    public void setPassword( String password ) {        this.password = password;    }    public void setEmail( String email ) {        this.Email = email;    }    @Override    public String toString() {        return "User{" +                "name='" + username + '\'' +                ", password='" + password + '\'' +                ", Email='" + Email + '\'' +                '}';    }}

注意在实现接口时，一定要实现
public void writeToParcel(Parcel dest, int flags);
public int describeContents();

并且此类一定要包含一个静态的CREATOR(见代码)

如果这个类还包含一个自定义类型的对象，那么这个自定义的类型也应当实现Parcelable接口。

并且，在writeToParcel这个函数中使用writeParcelable方法来写入Parcel，在获取Parcel中的对象时（见代码的

public UserData(Parcel in) 构造函数），要使用readParcelable读取.

二、传递List的自定义类型
传递List的自定义类型与上方类似，只是在写入Parcel和读取时有所不同

本人有一个小小的实例，这是一个包含两个类型的例子：

Tag.java

public class Tag implements Parcelable{    private String tag_name;    private String tag_num;    private String tag_url;    public List articles = new ArrayList<>();    @Override    public void writeToParcel(            Parcel dest,            int flags            ) {        dest.writeString(this.getTag_name());        dest.writeString(this.getTag_num());        dest.writeString(this.getTag_url());        dest.writeTypedArray(                this.getArticles().toArray(new Article[this.getArticles().size()]),                flags        );    }    public Tag() {        this.tag_url = "";        this.tag_name = "";        this.tag_num = "";    }    public Tag( String _tag_name, String _tag_num, String _tag_url) {        this.tag_name = _tag_name;        this.tag_num = _tag_num;        this.tag_url = _tag_url;    }    public Tag( Parcel parcel ) {        this.tag_name = parcel.readString();        this.tag_num = parcel.readString();        this.tag_url = parcel.readString();        // Article[] temp = parcel.readParcelableArray(Article.class.getClassLoader());        Article[] temp = parcel.createTypedArray(Article.CREATOR);        this.articles = Arrays.asList(temp);    }    public static final Creator CREATOR = new Creator() {        @Override        public Tag createFromParcel(Parcel parcel) {            return new Tag(parcel);        }        @Override        public Tag[] newArray(int size) {            return new Tag[size];        }    };    @Override    public int describeContents() {        return 0;    }    public void setTag_name( String name ) {        this.tag_name = name;    }    public void setTag_num( String num ) {        this.tag_num = tag_num;    }    public void setTag_url( String url ) {        this.tag_url = url;    }    public String getTag_name() {        return this.tag_name;    }    public String getTag_num() {        return this.tag_num;    }    public String getTag_url() {        return this.tag_url;    }    public List getArticles() {        return articles;    }    public void setArticles(List articles) {        this.articles = articles;    }    @Override    public String toString() {        String article = "";        for (int i = 0; i < articles.size(); ++i) {            article += articles.get(i).toString() + "\n";        }        return                " : " + this.tag_num + " : " + this.tag_url + "\n" + article;    }}

Article.java

public class Article implements Parcelable{    private String title;    private String url;    private String date;    private String publisher;    @Override    public void writeToParcel(Parcel dest, int flags){        dest.writeString(this.title);        dest.writeString(this.url);    }    public Article() {        this.title = "";        this.url = "";    }    public Article(String _title, String _content) {        this.title = _title;        this.url = _content;    }    public Article( Parcel parcel ) {        this.title = parcel.readString();        this.url = parcel.readString();    }    public static final Creator CREATOR = new Creator() {        @Override        public Article createFromParcel(Parcel parcel) {            return new Article(parcel);        }        @Override        public Article[] newArray(int size) {            return new Article[size];        }    };    @Override    public int describeContents() {        return 0;    }    public void setTitle(String title) {        this.title = title;    }    public String getTitle() {        return title;    }    public String getUrl() {        return url;    }    public void setUrl(String url) {        this.url = url;    }    public String getDate() {        return date;    }    public void setDate(String date) {        this.date = date;    }    public String getPublisher() {        return publisher;    }    public void setPublisher(String publisher) {        this.publisher = publisher;    }    @Override    public String toString() {        return this.url;    }}

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