Question

Analyze the following code:

public class Test {
public static void main(String[] args) {
Object a1 = new A();
Object a2 = new Object();
System.out.println(a1);
System.out.println(a2);
}
}

class A {
int x;

public String toString() {
return "A's x is " + x;
}
}

(Choose more than one)

A. The program cannot be compiled because System.out.println(a1) is wrong, and it should be replaced by System.out.println(a1.toString()).
B. When executing System.out.println(a1), the toString() method in the Object class is invoked.
C. When executing System.out.println(a2), the toString() method in the Object class is invoked.
D. When executing System.out.println(a1), the toString() method in the A class is invoked.

Answer 1

The code correctly compiles and prints the output using the overridden toString() method from class A for a1 and from the Object class for a2. Options A and B are incorrect, while options C and D are correct.

Step-by-step explanation:

Let's analyze the given Java code snippet and the corresponding options.

Option A states that the program cannot compile because System.out.println(a1) is wrong and should be replaced by System.out.println(a1.toString()). This is not correct as Java automatically invokes the toString() method when an object is passed to System.out.println().

Option B is incorrect because when System.out.println(a1) is executed, the toString() method in class A is actually invoked since a1 is an instance of class A, not class Object.

Option C is correct, as when System.out.println(a2) is executed, the toString() method in the Object class is invoked because a2 is an instance of the Object class.

Finally, Option D is correct because the toString() method overridden in class A is called when System.out.println(a1) is executed, hence displaying "A's x is 0" since the default value of x is zero for an integer in Java.