error: If a primary key is annotated with autoGenerate, its type must be int, Integer, long or Long

Question

我试图创建一个整数 id 作为主键，然后它要求我创建 getter 和 setter 方法，然后它要我动态设置 id 但我不想在我的应用程序中添加一个 id 字段，如果我必须自己设置 id，autoGenerate 有什么用？

import android.arch.persistence.room.ColumnInfo;
import android.arch.persistence.room.Entity;
import android.arch.persistence.room.PrimaryKey;
import android.support.annotation.NonNull;

@Entity(tableName = "messages")
public class Message {

@PrimaryKey(autoGenerate = true)


@ColumnInfo(name = "message_date")
private String date;

@ColumnInfo(name = "message_timeHour")
private String timeHour;

@ColumnInfo(name = "message_timeMinute")
private String timeMinute;

@ColumnInfo(name = "message_contactName")
private String contactName;

@ColumnInfo(name = "message_text")
private String text;

public String getDate() {
    return date;
}

public void setDate(String date) {
    this.date = date;
}

public String getTimeHour() {
    return timeHour;
}

public void setTimeHour(String timeHour) {
    this.timeHour = timeHour;
}

public String getTimeMinute() {
    return timeMinute;
}

public void setTimeMinute(String timeMinute) {
    this.timeMinute = timeMinute;
}

public String getContactName() {
    return contactName;
}

public void setContactName(String contactName) {
    this.contactName = contactName;
}

public String getText() {
    return text;
}

public void setText(String text) {
    this.text = text;
}
}

这是什么意思，如何解决？

Answer 1

您需要使用 autoGenerate 属性

你的主键注释应该是这样的：

@PrimaryKey(autoGenerate = true)

引用here

Answer 2

每个@Entity 必须至少有一个主键。

@PrimaryKey(autoGenerate = true)

您应该将其用作

@PrimaryKey(autoGenerate = true) private int id;

此外，您应该为这个 id 变量设置一个 setter，这样当 Room 需要设置主键值时，它将使用您的 setter 方法，因为您的 id 变量是私有的。所以，现在在这种情况下你根本不需要设置 id 。房间会处理它。

error: If a primary key is annotated with autoGenerate, its type must be int, Integer, long or Long

error: If a primary key is annotated with autoGenerate, its type must be int, Integer, long or Long

java

database

android

android-studio

android-room