public class PowerSupply
 {
    public PowerSupply(String voltage){
        System.out.println ("PowerSupply(String) executed");
    }
    public PowerSupply(Object voltage){
        System.out.println ("PowerSupply(Object) executed");
    }
    public PowerSupply(){
        System.out.println ("No argument constructor execute");
    }
    public static void main(String[] args) {
        PowerSupply ps = new PowerSupply(null);
    }
 }

what would be the output ?

output:  PowerSupply(String) executed\

i dont know  why  the JVM is choosing the first constructor for
argument null .

please  explain...how this output coming ?