Question

我对使用房间持久性并不陌生，每当我尝试运行代码时都会遇到此错误。编辑时它没有显示错误，但是我在gradle上出现了构建错误。我不得不复制粘贴代码令我失望，但似乎都没有。错误低于

error: An entity must have at least 1 field annotated with @PrimaryKey

我该如何解决？我的代码在下面；

 package com.revosleap.dummy.DatabaseMov;

import android.arch.persistence.room.ColumnInfo;
import android.arch.persistence.room.Entity;
import android.arch.persistence.room.Ignore;
import android.arch.persistence.room.PrimaryKey;

@Entity

public class TodoListItem {
    @Ignore
    @PrimaryKey(autoGenerate = true)
     private int id;

    @ColumnInfo(name = "time")
    private String time;

    @ColumnInfo(name="title")
    private String title;

    public TodoListItem(){

    }

    public TodoListItem(String time, String title) {
        this.time = time;
        this.title = title;
    }

    public String getTime() {
        return time;
    }

    public void setTime(String time) {
        this.time = time;
    }

    public String getTitle() {
        return title;
    }

    public void setTitle(String title) {
        this.title = title;
    }

    public int getId() {
        return id;
    }

    public void setId(int id) {
        this.id = id;
    }
}

Answer 1

您不应将主键设为私有或静态

将此行private int id;更改为

@PrimaryKey
public int id;

更多详细信息Room entities

Answer 2

您不应将@Ignore与@PrimaryKey一起使用

@忽略注释从Room的处理中忽略标记的元素逻辑。

错误：实体必须至少具有1个用@PrimaryKey注释的字段

2 个答案: