Analyze the following code and choose two correct statements from below. public class Test extends A { public static void main(String[] args) { Test t = new Test(); t.print(); } } class A { String s; A(String s) { this.s = s; } public void print() { System.out.println(s); } } Group of answer choicesThe program does not compile because Test does not have a default constructor Test().The program has an implicit default constructor Test(), but it cannot be compiled, because its super class does not have a default constructor. The program would compile if the constructor in the class A were removed.The program would compile if a default constructor A(){ } is added to class A explicitly.The program compiles, but it has a runtime error due to the conflict on the method name print.
Question
Analyze the following code and choose two correct statements from below. public class Test extends A { public static void main(String[] args) { Test t = new Test(); t.print(); } } class A { String s; A(String s) { this.s = s; } public void print() { System.out.println(s); } } Group of answer choicesThe program does not compile because Test does not have a default constructor Test().The program has an implicit default constructor Test(), but it cannot be compiled, because its super class does not have a default constructor. The program would compile if the constructor in the class A were removed.The program would compile if a default constructor A(){ } is added to class A explicitly.The program compiles, but it has a runtime error due to the conflict on the method name print.
Solution 1
The two correct statements are:
- The program has an implicit default constructor Test(), but it cannot be compiled, because its super class does not have a default constructor.
- The program would compile if a default constructor A(){ } is added to class A explicitly.
Explanation:
In Java, every class has a default constructor implicitly if it does not define any constructors explicitly. However, if a class extends another class, the default constructor of the subclass will call the default constructor of the superclass implicitly. In this case, class Test extends class A, but class A does not have a default constructor (it only has a constructor that takes a String as a parameter). Therefore, the program cannot be compiled.
If a default constructor A(){ } is added to class A explicitly, the program would compile because the default constructor of class Test can call this default constructor of class A.
Solution 2
The two correct statements are:
- The program has an implicit default constructor Test(), but it cannot be compiled, because its super class does not have a default constructor.
- The program would compile if a default constructor A(){ } is added to class A explicitly.
Explanation:
In Java, if you don't define a constructor in a class, a default constructor is implicitly provided by the compiler. However, if you define a constructor with parameters and don't define a default constructor, the compiler doesn't provide a default constructor.
In this case, class A has a constructor with a parameter and doesn't have a default constructor. When class Test extends class A, it tries to call the default constructor of class A, but it doesn't exist, so the program doesn't compile.
To fix this, you can add a default constructor to class A.
Similar Questions
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