可以将 ArrayList<String> 转换为 ArrayList

Question

我在 Sharedpreferences 中保存了一些 ArrayList。但是我想在适配器中将我的自定义模型设置为 ArrayList 导致使用 getter 获取项目。我真的厌倦了来自 stackoverflow 的太多解决方案，但我做不到。

private ArrayList<String> fullList = new ArrayList<>();

到

private ArrayList<MyCustom> fullList = new ArrayList<>();

我的自定义类：

public class InstagramUserSummary implements Serializable {

public boolean is_verified;

public String profile_pic_id;

public boolean is_favorite;

public boolean is_private;

public String username;

public long pk;

public String profile_pic_url;

public boolean has_anonymous_profile_picture;

public String full_name;

@Override

public int hashCode() {

    return Objects.hash(username, pk);

}

@Override

public boolean equals(Object obj) {

    if (obj == this) return true;

    if (!(obj instanceof InstagramUserSummary)) {

        return false;

    }

    InstagramUserSummary user = (InstagramUserSummary) obj;

    return pk == user.getPk();

}}

列表是这样的：

[InstagramUserSummary(super=dev.niekirk.com.instagram4android.requests.payload.InstagramUserSummary@a4acf205, is_verified=false, profile_pic_id=1773528799482591987_1654599017, is_favorite=false, is_private=false, username=ququletta, pk=1654599017, profile_pic_url=https://instagram.fada1-5.fna.fbcdn.net/vp/8d99014623ed527e52512a20002d884b/5C387E45/t51.2885-19/s150x150/31203725_200759604054857_5778864946146181120_n.jpg, has_anonymous_profile_picture=false, full_name=Ququletta)]

谢谢。

Answer 1

解决方案：假设您在 MyCustom 类中有一个 String 变量，例如：public class MyCustom {&nbsp; &nbsp; private String strName;&nbsp; &nbsp; public MyCustom(String name) {&nbsp; &nbsp; &nbsp; &nbsp; this.strName = name;&nbsp; &nbsp; }&nbsp; &nbsp; public void setName(String name) {&nbsp; &nbsp; &nbsp; &nbsp; this.strName = name;&nbsp; &nbsp; }&nbsp; &nbsp; public String getName() {&nbsp; &nbsp; &nbsp; &nbsp; &nbsp;return this.strName;&nbsp; &nbsp; }}然后，您可以执行以下操作：for (MyCustom value : fullList) {&nbsp; &nbsp; customFullList.add(new MyCustom(value))}希望能帮助到你。

Answer 2

首先，没有必要让该username字段成为类的公共成员MyCustom。由于您通过 getter/setter 公开访问该字段是错误的。除此之外，您可以轻松使用流和映射函数MyCustom从字符串流创建新实例。为了避免样板代码，我会继续创建一个静态创建者方法，MyCustom如下所示：public class MyCustom {&nbsp; &nbsp; private String userName;&nbsp; &nbsp; public String getUserName() { return userName; }&nbsp; &nbsp; public void setUserName(String userName) { this.userName = userName; }&nbsp; &nbsp; public static MyCustom from(final String userName) {&nbsp; &nbsp; &nbsp; &nbsp; MyCustom custom = new MyCustom();&nbsp; &nbsp; &nbsp; &nbsp; custom.setUserName(userName);&nbsp; &nbsp; &nbsp; &nbsp; return custom;&nbsp; &nbsp; }}然后我将使用它作为方法引用将字符串转换为 MyCustoms，从而将它们收集到一个新列表中，如下所示：List<String> list = new ArrayList<>();List<MyCustom> customs = list.stream()&nbsp; &nbsp; &nbsp; &nbsp; .map(MyCustom::from)&nbsp; &nbsp; &nbsp; &nbsp; .collect(Collectors.toList());最后，还要避免使用具体类型初始化列表（例如ArrayList<String> someList = new ArrayList<>;'。对接口进行编码要好得多，因此执行类似List<String> someList = new ArrayList<>.