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Java Assessment

Q1. Given the string "strawberries" saved in a variable called fruit, what would "fruit.substring(2, 5)" return?

  • rawb
  • raw <<<<---Correct
  • awb
  • traw

Reasoning: The substring method is accepting two arugments. The first argument being the index to start(includes that char at 2) and the second the index of the string to end the substring(excludes the char at 5). Strings in Java are like arrays of chars. Therefore the method will return "raw" as those are the chars in indexs 2,3, and 4. You can also take the ending index and subtract the beginning index from it, to determine how many chars will be included in the substring (5-2=3).

Q2. How can you achieve runtime polymorphism in Java?

  • method overloading
  • method overrunning
  • method overriding <<<<--- Correct
  • method calling

Q3. Given the following definitions, which of these expression will NOT evaluate to true?

boolean b1 = true, b2 = false; int i1 = 1, i2 = 2;

  • (i1 | i2) == 3
  • i2 && b1 <<<<---Correct
  • b1 || !b2
  • (i1 ^ i2) < 4

Q4. What can you use to create new instances in Java?

  • constructor <<<<---Correct
  • another instance
  • field
  • private method

Q5. What is the output of this code?

1: class Main {
2:   public static void main (String[] args) {
3:     int array[] = {1, 2, 3, 4};
4:     for (int i = 0; i < array.size(); i++) {
5:        System.out.print(array[i]);
       }
     }
   }
  • It will not compile because of line 4. <<<<---Correct
  • It will not compile because of line 3.
  • 123
  • 1234

Q6. Which of the following can replace the CODE SNIPPET to make the code below print "Hello World"?

}
interface Interface2 {
    static void print() {
        System.out.print("World!");
    }
}
  • super1.print(); super2.print();
  • this.print();
  • super.print();
  • Interface1.print(); Interface2.print();

Q7. What does the following code print?

String str = ""abcde"";
str.trim();
str.toUpperCase();
str.substring(3, 4);
System.out.println(str);
  • CD
  • CDE
  • D
  • "abcde" <<<<---Correct

Q8. What is the result of this code?

1: class Main {
2:   public static void main (String[] args){
3:     System.out.println(print(1));
4:   }
5:   static Exception print(int i){
6:       if (i>0) {
7:          return new Exception();
8:       } else {
9:          throw new RuntimeException();
10:      }
11:  }
12: }
  • It will show a stack trace with a runtime exception.
  • "java.lang.Exception" <<<<---Correct
  • It will run and throw an exception.
  • It will not compile.

Q9. Which class can compile given these declarations?

1: interface One {
2:      default void method() {
3:          System.out.println(""One"");
4:      }   }
5: interface Two {
6:      default void method () {
7:          System.out.println(""One"");
8:      }   }

  class Three implements One, Two {
    publc void method() {
        super.One.method();
  } }

  class Three implements One, Two {
    publc void method() {
        One.method();
  } }

class Three implements One, Two {
}

  class Three implements One, Two { <------ correct
    publc void method() {
        One.super.method();
  } }

Q10. What is the output of this code?

1: class Main {
2:  public static void main (String[] args) {
3:      List list = new ArrayList();
4:      list.add("hello");
5:      list.add(2);
6:      System.out.print(list.get(0) instanceof Object);
7:      System.out.print(list.get(1) instanceof Integer);
8:  }
9: }
  • The code does not compile.
  • truefalse
  • truetrue <<<<---Correct
  • falsetrue

Q11. Given the following two classes, what will be the output of the Main class?

package mypackage;
public class Math {
    public static int abs(int num){
        return num<0?-num:num;
    }
}
package mypackage.elementary;
public class Math {
    public static int abs (int num) {
        return -num;
    }
}
1: import mypackage.Math;
2: import mypackage.elementary.*;

3: class Main {
4:  public static void main (String args[]){
5:      System.out.println(Math.abs(123));
6:  }
7: }
  • Lines 1 and 2 generate compiler erros due to class name conflicts.
  • "-123" <--- Correct
  • It will throw an exception on line 5.
  • "123"

Q12. What is the result of this code?

1: class MainClass {
2:  final String message(){
3:      return "Hello!";
4:  }
5: }

6: class Main extends MainClass {
7:  public static void main(String[] args) {
8:      System.out.println(message());
9:  }

10: String message(){
11:     return "World!";
12:  }
13: }
  • It will not compile because of line 10. <--- Correct
  • "Hello!"
  • It will not compile because of line 2.
  • "World!"

Q13. Given this code, which command will output "2"?

class Main {
    public static void main(String[] args) {
        System.out.println(args[2]);
    }
}
  • java Main 1 2 "3 4" 5
  • java Main 1 "2" "2" 5 <--- Correct
  • java Main.class 1 "2" 2 5
  • java Main 1 "2" "3 4" 5

Q14. What is the output of this code?

class Main {
    public static void main(String[] args){
        int a = 123451234512345;
        System.out.println(a);
    }
}
  • "123451234512345"
  • Nothing - this will not compile. <<<<---Correct
  • a negative integer value
  • "12345100000"

Reasoning: The int type in Java can be used to represent any whole number from -2147483648 to 2147483647. Therefore this code will not compile as the number assigned to 'a' is larger than the int type can hold.

Q15. What is the output of this code?

class Main {
    public static void main (String[] args) {
        String message = "Hello world!";
        String newMessage = message.substring(6, 12)
            + message.substring(12, 6);
        System.out.println(newMessage);
    }
}
  • The code does not compile.
  • A runtime exception is thrown <<<<---Correct
  • "world!!world"
  • "world!world!"
String m = "Hello world!";
String n = m.substring(6,12) + m.substring(12,6);
System.out.println(n);

Q17. How do you write a foreach loop that will iterate over ArrayList<Pencil>pencilCase?

for(Pencil pencil = pencilCase){}
Iterator iterator = pencilCase.iterator();
for(){iterator.hasNext()}{}

Q18. Fill in the blanks?

  • Object-oriented programming (OOP) is a programming language model that organizes software design around (objects), rather than (actions).

Q19. What code would you use to tell if "schwifty" is of type String?

  • "schwifty".getType() == String
  • "schwifty".getClass().getsimpleName() == "String"
  • "schwifty".getType().equals("String")
  • "schwifty" instanceof String <<<<---Correct

Q20. Correct output of "apple".compareTo("banana")

  • 0
  • positive number
  • negative number <<<<---Correct
  • compilation error

Q21. You have an ArrayList of names that you want to sort alphabetically. Which approach would NOT work?

  • names.sort(Comparator.comparing(String::toString))
  • Collections.sort(names)
  • names.sort(List.DESCENDING) <<<--- Correct (not too sure)
  • names.stream().sorted((s1, s2) -> s1.compareTo(s2)).collect(Collectors.toList())

Q22. By implementing encapsulation, you cannot directly access the class's _____ properties unless you are writing code inside the class itself.

  • private <<<<---Correct
  • protected
  • no-modifier
  • public

Q23. Which is the most up-to-date way to instantiate the current date?

  • new SimpleDateFormat("yyyy-MM-dd").format(new Date())
  • new Date(System.currentTimeMillis())
  • LocalDate.now()
  • Calender.getInstance().getTime() <<<<--- Correct

Q24. Fill in the blank to create a piece of code that will tell wether int0 is divisible by 5:

boolean isDivisibleBy5 = _____
  • int0 / 5 ? true: false
  • int0 % 5 == 0 <<<<---Correct
  • int0 % 5 != 5
  • Math.isDivisible(int0, 5)

Q25. How many time will this code print "Hello World!"?

Class Main {
    public static void main(String[] args){
        for (int i=0; i<10; i=i++){
            i+=1;
            System.out.println("Hello World!");
        }
    }
}
  • 10 times
  • 9 times
  • 5 times <<<<---Correct
  • infinite number of times

Q26. The runtime system starts your program by calling which function first?

  • print
  • iterative
  • hello
  • main <<<<---Correct

Q27. What is the result of this code?

try{
    System.out.print("Hello World");
}catch(Exception e){
    System.out.println("e");
}catch(ArithmeticException e){
    System.out.println("e");
}finally{
    System.out.println("!")
}
  • It will throw a runtime exception
  • It will not compile <<<<---Correct
  • Hello World!
  • Hello World

Q28. Which statement is NOT true?

  • An anonymous class may specify an abstract base class as its base type.
  • An anonymous class does not require a zero-argument constructor. <<<<---Correct
  • An anonymous class may specify an interface as its base type.
  • An anonymous class may specify both an abstract class and interface as base types

Q29. What will this program print out to the console when executed?

public class Main {
    public static void main(String[] args){
       LinkedList<Integer> list = new LinkedList<>();
       list.add(5);
       list.add(1);
       list.add(10);
       System.out.println(list);
    }
}
  • [5, 1, 10] <<<<---Correct
  • [10, 5, 1]
  • [1, 5, 10]
  • [10, 1, 5]

Q30. What is the output of this code?

class Main {
    public static void main(String[] args){
       String message = "Hello";
       for (int i = 0; i<message.length(); i++){
          System.out.print(message.charAt(i+1));
       }
    }
}
  • "Hello"
  • A runtime exception is thrown. <<<<---Correct
  • The code does not compile.
  • "ello"

Q31. Object-oriented programming is a style of programming where you organize your program around ____ rather than ____ and data rather than logic.

  • functions; actions
  • objects; actions
  • actions; functions
  • actions; objects