Put associated classes in separate source files

Question

I have two classes, User and Wallet . If I put them in a single file, everything works fine. How can I put them in separate files like Wallet.java and User.java ?

When I tried User.java threw an error because it didn't not know what Wallet was.

public class Wallet{
    float winningAmount;
    float bonusAmount;
    float depositAmount;
    public Wallet(float winningAmount, float bonusAmount, float depositAmount){
      this.winningAmount = winningAmount;
      this.bonusAmount = bonusAmount;
      this.depositAmount = depositAmount;
    }
    public void debitBonus(float amountToDebit){
      this.bonusAmount = this.bonusAmount - amountToDebit;
    }
    public void debitDeposit(float amountToDebit){
      this.depositAmount = this.depositAmount - amountToDebit;
    }
    public void debitWinnings(float amountToDebit){
      this.winningAmount = this.winningAmount - amountToDebit;
    }
   }
  

public class User{
    int id;
    String name;
    String email;
    String mobileNumber;
    boolean isVerified;
    Wallet wallet;
    User(int id, String name, String email, String mobileNumber,Wallet wallet){
      this.id = id;
      this.name = name;
      this.email = email;
      this.mobileNumber = mobileNumber;
      this.isVerified = false;
      this.wallet = wallet;
    }
  }

Answer 1

If both files are in the same package it should work immediately.

If they are in different packages, just add an import statement to import Wallet into User :

User.java

package com.domain.package1;

import com.domain.package2.Wallet;

public class User {
    Wallet wallet;
}

Wallet.java

package com.domain.package2;

public class Wallet {
}