is there a way to run an instance/object of this type using Junit. The
reason is that I want to call setVar for setting var. junit can run
class but can it run an object of this class?

something like

import org.junit.*;
import org.junit.After;
import org.junit.Test;
import org.junit.Before;

public class TT  {

    private String var =null;

    public setVar(String s){
     var = s;
    }

    @Before
    public void Before(){
    }

    @Test
    public void tt(){
        System.out.println("Test1" );
    }
    @Test
    public void tt2(){
        System.out.println("Test2" );
    }
    @Test
    public void tt3(){
        System.out.println("Test3" );
    }

    @After
    public  void After() throws Exception {
        System.out.println("after");

    }

}