在 MainActivity 中初始化一个对象，然后全局访问它

Question

我想在我的 MainActivity 中创建一个对象，但我想全局访问它，所以假设我有这个类public class User {private String description;private String display_name;private String email;private String followers;private String following;private String posts;private String profile_photo;private String user_id;private String username;public User(){}public User(String description, String display_name, String email, String followers, String following, String posts, String profile_photo, String user_id, String username) {    this.description = description;    this.display_name = display_name;    this.email = email;    this.followers = followers;    this.following = following;    this.posts = posts;    this.profile_photo = profile_photo;    this.user_id = user_id;    this.username = username;}public String getDescription() {    return description;}public void setDescription(String description) {    this.description = description;}public String getDisplay_name() {    return display_name;}public void setDisplay_name(String display_name) {    this.display_name = display_name;}public String getEmail() {    return email;}public void setEmail(String email) {    this.email = email;}public String getFollowers() {    return followers;}public void setFollowers(String followers) {    this.followers = followers;}public String getFollowing() {    return following;}public void setFollowing(String following) {    this.following = following;}public String getPosts() {    return posts;}public void setPosts(String posts) {    this.posts = posts;}public String getProfile_photo() {    return profile_photo;}public void setProfile_photo(String profile_photo) {    this.profile_photo = profile_photo;}public String getUser_id() {    return user_id;}public void setUser_id(String user_id) {    this.user_id = user_id;}public String getUsername() {    return username;}public void setUsername(String username) {    this.username = username;                '}';    }}

Answer 1

我建议你按照下面的程序。您可以在应用程序的整个生命周期中创建全局变量保持值，而不管运行哪个活动。

1.扩展基本的Application类

扩展基android.app.Application类并添加成员变量，如下所示：

    public class myUser extends Application {

    private String description;

    ...

    public String getDescription() {

         return description;

    }

    public void setDescription(String description) {

         this.description = description;

    }

    ...

   }

2.在Manifest中声明：

在您的 android 中，manifest您必须声明实现类android.app.Application（将android:name=".myUser"属性添加到现有应用程序标签）：

<application 

  android:name=".myUser" 

  android:icon="@drawable/my_icon" 

  android:label="@string/app_name">

3. 在活动中设置/获取变量

在你的活动，你可以片段get和set像这样的变量：

// initialise your user variable

// set description variable

((myUser) this.getApplication()).setDescription("your description");

// get description variable

String s = ((myUser) this.getApplication()).getDescription();

希望它会帮助你。