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BJP4 Self-Check 9.9: CarTruck2

Language/Type: Java classes inheritance mystery
Author: Marty Stepp (on 2016/09/08)

Consider the following two classes: 

public class Car {
    public void m1() {
        System.out.println("car 1");
    }

    public void m2() {
        System.out.println("car 2");
    }

    public String toString() {
        return "vroom";
    }
}

public class Truck extends Car {
    public void m1() {
        System.out.println("truck 1");
    }
     
    public void m2() {
        super.m1();
    }
     
    public String toString() {
        return super.toString() + super.toString();
    }
}

And assuming that the following variable has been declared: 

Truck mytruck = new Truck();

What is the output from the following statements?

System.out.println(mytruck);
mytruck.m1();
mytruck.m2();

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