Java class object in Kotlin

Question

I am working on a database, which requires user to register and login. When the use registers, the data gets stored into a room database. For the registration purpose, Kotlin code is used. But I want to use a Object of java class inside that Kotlin code.

Therefore, my query is it possible to initialise an object of Java class inside a Kotlin code?

For example:
user.java

package ...

public class User {
    /*   The credentials of a user. */
    String userName, password, bID;
    /* Last message */
    String lastMessage;

    public User(String userName, String password, String bID, String lastMessage) {
        this.userName = userName;
        this.password = password;
        this.bID = bID;
        this.lastMessage = lastMessage;
    }
    ....
}

**register.kt:**

 package... import android.content.Intent import androidx.appcompat.app.AppCompatActivity import android.os.Bundle import android.widget.Toast import kotlinx.android.synthetic.main.activity_register.* class RegisterActivity: AppCompatActivity() { override fun onCreate(savedInstanceState: Bundle?) { super.onCreate(savedInstanceState) setContentView(R.layout.activity_register) // handler= DatabaseHelper(this) val handler= DatabaseHelper(this) User user = new user(); btnLogRegister.setOnClickListener { onBackPressed() } reg_button.setOnClickListener{ handler.insertUserData(reg_bluetooth_name.text.toString(),reg_username.text.toString(),reg_password.text.toString()) Toast.makeText(this,"Values Inserted", Toast.LENGTH_LONG).show() } } }

I want to insert the java class object inside the register .kt

Answer 1

Change

User user = new User( ) 
//to this line
val user = User ( )

Answer 2

You have to use data class in kotlin like below

data class User (
  val userName : String = "",
  val password : String = "",
  val bID : String = "",
  val lastMessage : String = ""
)

How to use it

reg_button.setOnClickListener{
            handler.insertUserData(User(reg_bluetooth_name.text.toString(),reg_username.text.toString(),reg_password.text.toString()))
                Toast.makeText(this,"Values Inserted", Toast.LENGTH_LONG).show()

        }

Answer 3

For kotlin, use data class, and to enjoy more features of kotlin like checking for nullability make you class like this,

data class User (var userName : String?,var password : String?,var bID : String?,var lastMessage : String?
)

Using var enable use to get both setters and getters whereas val will only give you getters. Note that the

`User (var userName : String?,var password : String?,var bID : String?,var lastMessage : String?)` 

is the primary constructor and you can create more.

And in you activity you can force unwrap the values as shown in the code or use default values.

reg_button.setOnClickListener{
            handler.insertUserData(reg_bluetooth_name.text.toString()!,reg_username.text.toString()!,reg_password.text.toString()!)
                Toast.makeText(this,"Values Inserted", Toast.LENGTH_LONG).show()

        }