Accessing Object variable and primitive variable

public static void main(String[] args) {

    test t;

    test s=new test();

    s.y=12;

    t=s;

    s.y++;

    System.out.println(s.y+"\t"+t.y);

    int k,j=12;

    k=j;

    j++;

    System.out.println(k+"\t"+j);

    }

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OUTPUT

13        13

12        13

Java:Passing object means passing address, but not for primitive

class objx{

    int z;

    public objx(int d) {

        z=d;

    }

}

public class Main {

 public void inc(int y)

    {

         y++;

    }

    public void incObj(objx ob1)

    {

    ob1.z++;

    }

    public static void main(String[] args) {

       Main m=new Main();

       int j=2;

       objx ob=new objx(4);

       m.inc(j);

       m.incObj(ob);

       System.out.println(j+"\n"+ob.z);

     }

}

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Output

2

5