Question

Question 2 (1 point) Saved Choose the option that best describes what happens when the bolded println() statement is executed: public class Point { public static void main(String[] args) { Point p 1 = new Point(3, 4); System.out.println(p1); } public int x, y; public Point(int xx, int yy) { x = xx; y = yy; } سی Point inherited a toString() method, which is called internally by println(). This is a compile error - println doesn't know how to handle a Point. Java synthesizes a toString() method for us with default behavior, and that gets called. This is a compile error - Point did not extend Object and therefore did not inherit toString()

please help

Answer 1

2. Java systhesizes a toString() method for us with default behaviour, and that gets called.

Explanation:

In java, if object is printed then toString() method is directly invoked by the compiler. You can see the executed code with it's output in the picture below.

9 Execute > Share e File STDIN 1. public class Point{ 5 public static void main(String []args) { Point p1 = new Point(3, 4); //object creation of Point class. pl holds the object reference address the object System.out.println(p1); //compiler writes "pl. tostring()" and prints hashcode value of thd object pi public int x,y://variable declaration public Point(int xx, int yy){ X=XX; //assign xx value to the instance variable x. y=yy; //assign yy value to the instance variable y } 9 10 11 12} 1. Result Sjavac Point.java Sjava -Xmx128M -Xms 16M Point Point@6d06d69c

3. The compiler enforces that checked exceptions are caught or thrown.

Explanation:

Checked exceptions are checked at compile time and they are forced by java compiler to be caught or thrown in the method signature(using throws keyword). For example IOException, SQLException etc are checked exceptions.

4. The variable declaration which causes compile time error is:

Chicken clara = new Bird();

Explanation:

You can refer the below executed code and it's output. Explanation is added in the comments.

1 } 5 } Execute > Share e File STDIN class Animal 2. public Animal 3 System.out.println("Animal"); 4 } 6. class Bird extends Animal{ 7. public Bird 8 System.out.println("Bird"); 9 10 } 11 - class Chicken extends Bird{ 12 public Chicken() { 13 System.out.println("Chicken"); 14 15} 16. public class HelloWorld{ 17 public static void main(String [jargs) { 19 Animal bob - (Bird)(new Chicken(); //object creation of Chicken using super class reference, chicken is cype casted to Bird and assigned to the the type Animal 20 System.out.println("--------"); 21 Chicken clara = new Bird(); //object creation of Bird(super class of chicken and sub class of animal) and assigned to the chicken (sub class) reference. 22 Chicken billi - (Chicken)(new Chicken(); //object creation of Chicken using same class reference 23 System.out.println("--------"); 24 Bírd happy new Chicken(); //object creation of chicken using Bird(super class) reference 25 26 ) } 18 - 1. le Result Sjavac HelloWorld.java HelloWorld.java:21: error: incompatible types: Bird cannot be converted to Chicken Chicken clara = new Bird(); //object creation of Bird(super class of chicken and sub class of Animal) and assigned to the 1 error

} Execute > Share e File STDIN 1. class Animal 2. public Animal({ 3 System.out.println("Animal"); 4 } 5} 6. class Bird extends Animal 7 public Bird) { 8 System.out.println("Bird"); 9 10} 11 - class Chicken extends Bird{ 12 public Chicken() { 13 System.out.println("Chicken"); 14 15 16. public class HelloWorld{ 17 18 - public static void main(String []args) { 19 Animal bob = (Bird) (new Chicken(); //object creation of chicken using super class reference. Chicken is type casted to Bird and assigned to the the type Animal 20 System.out.println("--------"); 21 chicken clara = new Bird(:7/object creation of Bird( super class of chicken and sub class of Animal) and assigned to the chicken (sub class) reference, 22 Chicken billi = (Chicken) (new Chicken(); //object creation of Chicken using same class reference 23 System.out.println(""); 24 Bird happy = new Chicken(); //object creation of chicken using Bird(super class) reference 25 } 26 ) 1. ln Result --------- SO Sjava - Xmx128M - Xms 16M HelloWorld Animal Bird Chicken Animal Bird Chicken Animal Bird Chicken

5. Difference between errors and exceptions in java is:

Exceptions are throwable, errors are not.

Other options are not correct because

-> Errors cannot be recovered.

-> Error and RuntimeException classes are unchecked, everything else in Throwable class is checked.

-> Exceptions are thrown as a result of a problem with the JVM.