Private & Public Access Modifiers

Access Modifiers:

• The access modifiers in Java specifies the accessibility or scope of a variable, method, constructor, or class.
• We can change the access level of variables, constructors, methods, and class by applying the access modifier on it.
• There are four types of Java access modifiers:
  • private
  • public
  • default
  • protected

Private:

• The access level of a private modifier is only within the class.
• It cannot be accessed from outside the class.

Public:

• The access level of a public modifier is everywhere.
• It can be accessed from within the class, outside the class, within the package and outside the package.

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SCENARIO 1:

• In this example, we have created two classes StateBank and SBICustomer.
• StateBank class contains private variables.
• We are accessing these private variables from outside the SBICustomer class, so there is a compile-time error.

StateBank Class:

public class StateBank
{

private int minBalance = 1000;
private String custName;

public void deposit()
{
System.out.println("Deposit");
}

public void withdraw()
{
System.out.println("Withdraw");
}

}

SBICustomer Class:

• This SBICustomer class is common for all scenario.

public class SBICustomer
{

public static void main(String[] args)
{
StateBank rep = new StateBank();
rep.deposit();
rep.withdraw();
System.out.println(rep.minBalance);
}
}

ERROR:

• minBalance has private access in StateBank
• System.out.println(rep.minBalance);

Solution:

• Change the variable access type into public or default.

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SCENARIO 2:

• StateBank class contains private methods.
• We are accessing these private methods from outside the SBICustomer class, so there is a compile-time error.

StateBank Class:

public class StateBank
{

int minBalance = 1000;
String custName;

private void deposit()
{
System.out.println("Deposit");
}

private void withdraw()
{
System.out.println("Withdraw");
}

}

Refer Scenario 1 for SBICustomer class.

ERROR:

• deposit() has private access in StateBank
• rep.deposit();
• withdraw() has private access in StateBank
• rep.withdraw();

Solution:

• Change the method access type into public.

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SCENARIO 3:

• StateBank class is a private class.
• We are accessing these private class from outside the SBICustomer class, so there is a compilation error.

StateBank class:

private class StateBank
{

int minBalance = 1000;
String custName;

public void deposit()
{
System.out.println("Deposit");
}

public void withdraw()
{
System.out.println("Withdraw");
}

}

Refer Scenario 1 for SBICustomer class.

ERROR:

• modifier private not allowed here
• private class StateBank

Solution:

• Change the class access type into public.

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SCENARIO 4:

• Constructor access type is private.
• So we get compilation error.

StateBank Class:

public class StateBank
{

int minBalance = 1000;
String custName;
	
private StateBank()
{
System.out.println("Zero Argument Constructor");
}
	
public void deposit()
{
System.out.println("Deposit");
}

public void withdraw()
{
System.out.println("Withdraw");
}

}

Refer Scenario 1 for SBICustomer class.

ERROR:

• StateBank() has private access in StateBank
• StateBank rep = new StateBank();

Solution:

• Change the constructor access type into public.

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