Android 带有 Room 数据库的 ExpandableListview

Question

我需要填充一个 ExpandableListView，其数据是从 Room 数据库中获取的。

有关于如何使用 SQLiteDatabase 执行此操作的答案：

1) Android ExpandableListView and SQLite Database

2) Android ExpandableListView From Database

是否可以使用 Room Database 实现相同的功能？

我有两个表：a) GroupHeader b) GroupContent

@Entity
public class GroupHeader implements Serializable {
    @PrimaryKey(autoGenerate = true)
    private int groupId;
    private String groupName;
    private String otherProperty1;
    private String otherProperty2;
    /* getters and setters */
}

@Entity
public class GroupContent implements Serializable {
    @PrimaryKey(autoGenerate = true)
    private int contentId;
    private int groupId;
    private String contentName;
    private String otherProperty3;
    private String otherProperty4;    
    /* getters and setters */
}

有什么建议吗？

Answer 1

使用 @Relation 找到了解决方案。

参考：https://developer.android.com/reference/android/arch/persistence/room/Relation

@Entity
public class GroupHeader implements Serializable {
    @PrimaryKey(autoGenerate = true)
    private int groupId;
    private String groupName;
    private String otherProperty1;
    private String otherProperty2;
    /* getters and setters */
}

@Entity
public class GroupContent implements Serializable {
    @PrimaryKey(autoGenerate = true)
    private int contentId;
    private int groupId;
    private String contentName;
    private String otherProperty3;
    private String otherProperty4;    
    /* getters and setters */
}

public class Wrapper {
    @Embedded
    private GroupHeader header;
    @Relation(parentColumn="groupId", entityColumn="groupId", entity=GroupContent.class)
    private List<GroupContent> contents;
    /*getters & setters*/
}

Android 带有 Room 数据库的 ExpandableListview

Android ExpandableListview with Room database

android

android-database

android-room