Why private and get and Set?

Hello!

Every body has read that you should incapsulate your mambers as god as you can if possible. Instead of public members you should declare them private and create get and set methods. But if you have this class:

public class A
{
    private String a;
   
    public String getA()
    {
        return a
    }
   
    public void setA(String a)
    {
        this.a = a;
    }
}

//and

public class B
{
    public String b;
}

I would say that for safety and memory reson this would be equal The memory would be the same (If instans of class A would be garbage collected we still have refereces to object a):

A classA;
B classB;
//...
classB.b = "Hello";
String j = classB.b;
//or
classA.setA("Hello");
String i = classA.getA();

Please correct me if I am wrong?

If you would have something like this it would be better:
public class A
{
    private String a;
   
    public String getA()
    {
        return a.clone();
    }
   
    public void setA(String a)
    {
        this.a = a.clone();
    }
}

Now if the instans of A would be gb the object a also would go.

So please correct me if I am wrong when I say that the first code of A wouldn't be any better then the code of B. Or is there any other performance or safety winning of coding like A?

Best regards
Fredrik

PS Please give ansvers so you could get part of the points