How to make primary key as autoincrement for Room Persistence lib

You need to use the autoGenerate property

Your primary key annotation should be like this:

@PrimaryKey(autoGenerate = true)

Reference for PrimaryKey.

You can add @PrimaryKey(autoGenerate = true) like this:

@Entitydata class Food(        var foodName: String,         var foodDesc: String,         var protein: Double,         var carbs: Double,         var fat: Double){    @PrimaryKey(autoGenerate = true)    var foodId: Int = 0 // or foodId: Int? = null    var calories: Double = 0.toDouble()}

add @PrimaryKey(autoGenerate = true)

@Entitypublic class User {    @PrimaryKey(autoGenerate = true)    private int id;    @ColumnInfo(name = "full_name")    private String name;    @ColumnInfo(name = "phone")    private String phone;    public User(){    }    //type-1    public User(String name, String phone) {        this.name = name;        this.phone = phone;    }    //type-2    public User(int id, String name, String phone) {        this.id = id;        this.name = name;        this.phone = phone;    }}

while storing data

 //type-1 db.userDao().InsertAll(new User(sName,sPhone));  //type-2 db.userDao().InsertAll(new User(0,sName,sPhone)); 

type-1

If you are not passing value for primary key, by default it will 0 or null.

type-2

Put null or zero for the id while creating object (my case user object)

If the field type is long or int (or its TypeConverter converts it to a long or int), Insert methods treat 0 as not-set while inserting the item.

If the field's type is Integer or Long (Object) (or its TypeConverter converts it to an Integer or a Long), Insert methods treat null as not-set while inserting the item.