What is wrong in the following code?

public class Test {

  public static void main(String[] args) {
    Number x = new Integer(3);
    System.out.println(x.intValue());
    System.out.println((Integer) x.compareTo(new Integer(4)));
  }
}

(Enable GeometricObject comparable) Modify the GeometricObject class to implement the Comparable interface and define a static max method in the GeometricObject class for finding the larger of two GeometricObject objects. Draw the UML diagram and implement the new GeometricObject class. Write a test program that uses the max method to find the larger of two circles, the larger of two rectangles.

Trace the program carefully and show the output of the following code. Rational r1 = new Rational(1, 2); Rational r2 = new Rational(1, -2); System.out.println(r1.add(r2));

Show the output of the following code. public class Test { public static void main(String[] args) { Number x = 3; System.out.println(x.intValue()); System.out.println(x.doubleValue()); } }

What is wrong in the following code?

public class Test {

  public static void main(String[] args) {
    GeometricObject x = new Circle(3);
    GeometricObject y = x.clone();
    System.out.println(x == y);
  }
}

How do you simplify the code in lines 82–85 in Listing 13.13 Rational.java using one line of code without using the if statement?

True or false? a. An abstract class can be used just like a nonabstract class except that you cannot use the new operator to create an instance from the abstract class. b. An abstract class can be extended. c. A subclass of a nonabstract superclass cannot be abstract. d. A subclass cannot override a concrete method in a superclass to define it as abstract. e. An abstract method must be nonstatic.

What is wrong in the following code? public class Test { public static void main(String[] args) { Person[] persons = {new Person(3), new Person(4), new Person(1)}; java.util.Arrays.sort(persons); } } class Person { private int id; Person(int id) { this.id = id; } }

Show the output of the following code:

ArrayList<String> list = new ArrayList<>();
list.add("New York");
ArrayList<String> list1 = list;
ArrayList<String> list2 = (ArrayList<String>)(list.clone());
list.add("Atlanta");
System.out.println(list == list1);
System.out.println(list == list2);
System.out.println("list is " + list);
System.out.println("list1 is " + list1);
System.out.println("list2.get(0) is " + list2.get(0));
System.out.println("list2.size() is " + list2.size());

Why is the following code wrong? Object r1 = new Rational(-2, 6); Rational r2 = new Rational(1, 45); System.out.println(r2.compareTo(r1));

True or false? a. An interface is compiled into a separate bytecode file. b. An interface can have static methods. c. An interface can extend one or more interfaces. d. An interface can extend an abstract class. e. An abstract class can extend an interface.

Write the following method that sorts an ArrayList of numbers. public static void sort(ArrayList list)

Why do the following two lines of code compile but cause a runtime error? Number[] numberArray = new Integer[2]; numberArray[0] = new Double(1.5);

Can you create a Calendar object using the Calendar class?