当我在字段上创建带有“ primaryKey”注释的“ Entity”以使用Room创建任何SQLite表时,Android Studio项目成功构建。但是,当我尝试使用复合主键创建“实体”时,无法构建项目。
不幸的是,由于我在项目中使用“ Dagger 2”,因此无法看到实际的构建错误。

注意:Project符合Kotlin编译器。

码:

@Entity(tableName = "thread_users", primaryKeys = {"thread_id", "user_id"})
public class DMThreadUsers {
    @ColumnInfo(name = "thread_id")
    private String threadId;
    @ColumnInfo(name = "user_id")
    private String userId;
    @ColumnInfo(name = "is_left")
    private boolean isLeft;

    public DMThreadUsers() {
    }

    public String getThreadId() {
        return threadId;
    }

    public void setThreadId(String threadId) {
        this.threadId = threadId;
    }

    public String getUserId() {
        return userId;
    }

    public void setUserId(String userId) {
        this.userId = userId;
    }

    public boolean isLeft() {
        return isLeft;
    }

    public void setLeft(boolean left) {
        isLeft = left;
    }
}

最佳答案

主键字段应使用@NonNull注释。您必须在JAVA中为主键字段注释@NonNull,而在KOTLIN中,需要初始化主键字段。

@Entity(tableName = "thread_users", primaryKeys = {"thread_id", "user_id"})
public class DMThreadUsers {
    @NonNull
    @ColumnInfo(name = "thread_id")
    private String threadId;
    @NonNull
    @ColumnInfo(name = "user_id")
    private String userId;
    @ColumnInfo(name = "is_left")
    private boolean isLeft;

    public DMThreadUsers() {
    }

    public String getThreadId() {
        return threadId;
    }

    public void setThreadId(String threadId) {
        this.threadId = threadId;
    }

    public String getUserId() {
        return userId;
    }

    public void setUserId(String userId) {
        this.userId = userId;
    }

    public boolean isLeft() {
        return isLeft;
    }

    public void setLeft(boolean left) {
        isLeft = left;
    }
}

09-10 06:09
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