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Java Tutorial » Class Definition » Defining Class  
5.1.9.Class with a constructor to initialize instance variablesPrevious/Next
public class MainClass
{
   public static void mainString args[] ) 
   {
      Account account1 = new Account50.00 )// create Account object
      Account account2 = new Account-7.53 )// create Account object

      System.out.printf"account1 balance: $%.2f\n", account1.getBalance() );
      System.out.printf"account2 balance: $%.2f\n\n", account2.getBalance() );
      
      double depositAmount; // deposit amount read from user

      depositAmount = 10.10;
      account1.creditdepositAmount )// add to account1 balance

      System.out.printf"account1 balance: $%.2f\n", account1.getBalance() );
      System.out.printf"account2 balance: $%.2f\n\n", account2.getBalance() );

      depositAmount = 12.12
      account2.creditdepositAmount )// add to account2 balance

      System.out.printf"account1 balance: $%.2f\n", account1.getBalance() );
      System.out.printf"account2 balance: $%.2f\n", account2.getBalance() );
   }

}

class Account
{   
   private double balance; // instance variable that stores the balance

   // constructor  
   public Accountdouble initialBalance )
   {
      if initialBalance > 0.0 
         balance = initialBalance; 
   }

   public void creditdouble amount )
   {      
      balance = balance + amount;
   }

   public double getBalance()
   {
      return balance;
   }

}
account1 balance: $50.00
account2 balance: $0.00

account1 balance: $60.10
account2 balance: $0.00

account1 balance: $60.10
account2 balance: $12.12
5.1.Defining Class
5.1.1. What Is a Java Class?
5.1.2. Fields
5.1.3. Defining Classes: A class has fields and methods
5.1.4. Creating Objects of a Class
5.1.5. Checking whether the object referenced was of type String
5.1.6. Class declaration with one method
5.1.7. Class declaration with a method that has a parameter
5.1.8. Class that contains a String instance variable and methods to set and get its value
5.1.9. Class with a constructor to initialize instance variables
5.1.10. Specifying initial values in a class definition