Question

public class GreeterTest

{

   public static void main(String[] args)

   {

// create an object for Greeter class

Greeter greeter = new Greeter("Jack");

// create two variables

Greeter var1 = greeter;

Greeter var2 = greeter;

// call the sayHello method on the first Greeter variable

String res1 = var1.sayHello();

System.out.println("The first reference " + res1);

// Call the setName method on the secod Grreter variable

var2.setName("Mike");

String res2 = var2.sayHello();

System.out.println("The second reference " + res2);

   }

}

public class Greeter

{

   public Greeter(String aName)

   {

   }

public void setName(String newName)

{

   this.Name = newName;

}

   public String sayHello()

   {

return "Hello, "+ Name + "!";

   }

   private String Name;

   }

The output will be

The first reference Hello, null!

The second reference Hello, Mike!

How to change the first sentence to "The first reference Hello, Jack!"

Answer 1

Please find the code here:

Name is not initialized in the constructor of Greeter class. So it is printing null.

public class GreeterTest

{

public static void main(String[] args)

{

// create an object for Greeter class

Greeter greeter = new Greeter("Jack");

// create two variables

Greeter var1 = greeter;

Greeter var2 = greeter;

// call the sayHello method on the first Greeter variable

String res1 = var1.sayHello();

System.out.println("The first reference " + res1);

// Call the setName method on the secod Grreter variable

var2.setName("Mike");

String res2 = var2.sayHello();

System.out.println("The second reference " + res2);

}

}

class Greeter

{

public Greeter(String aName)

{
this.Name = aName;
}

public void setName(String newName)

{

this.Name = newName;

}

public String sayHello()

{

return "Hello, "+ Name + "!";

}

private String Name;

}

OUTPUT:

The first reference Hello, Jack!
The second reference Hello, Mike!