错误：实体必须至少有 1 个用 @PrimaryKey 注释的字段

Question

我是使用房间持久性的新手，每当我尝试运行我的代码时都会出现此错误。编辑时没有显示错误，但我在 gradle 上遇到构建错误。我不得不复制粘贴代码，但似乎没有任何效果，这让我很失望。错误如下

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

我该如何解决？我的代码如下；

 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

您不应该将主键设为私有或静态

private int id; 将此行更改为

@PrimaryKey
public int id;

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