Questions.txt

Q1)
Given:
 class X {
    static int MAX_VAL = 100;
    int value = 99;
    public void setVal(int x) {
      if (x <= MAX_VAL) value = x;
    }
  }
And:
    X a = new X();
    X b = new X();
    a.setVal(120);
    System.out.print(a.value + ", ");
    b.MAX_VAL = 150; // EXACTLY EQUIVALENT to X.MAX_VAL!!!!
    a.setVal(140);
    System.out.println(a.value);

What is the result?
    A) 99, 99
    B) 120, 140
    C) 99, 140
    D) Compilation failure
    E) Exception at runtime

Q2)
Given:
  class Y {
    static String sayHi() { return "Y-Hello"; }
    String sayHi2() { return "Y-Hello2"; }
  }
And:
  class Z extends Y {
    static String sayHi() { return "Z-Hello"; }
    String sayHi2() { return "Z-Hello2"; }
  }
And this code fragment:
    Y y = new Z();
    System.out.println(y.sayHi() + ", " + y.sayHi2());

What is the result?
    A) Y-Hello, Y-Hello2
    B) Y-Hello, Z-Hello2
    C) Z-Hello, Z-Hello2
    D) Z-Hello, Y-Hello2
    E) Compilation fails

Q3)
given (all the Date/Holiday code and...)

    _____ () {
        return "Holiday called " +  name;
    }

What must fill the blank to cause current test code to output: Holiday called DecemberDay!

No A) String toString
No B) void toString
No C) @Override String toString
Yes D) public String toString
No E) None of the above!

Q4)
Given:
  class Base {
    void doBaseStuff() { System.out.println("doBaseStuff"); }
  }
and:
  class Sub extends Base {
    void doBaseStuff() { System.out.println("doSubStuff"); }
    void doOtherStuff() { System.out.println("doOtherStuff"); }
  }

In the Base and Sub classes, which three are true in isolation? (Choose 3)
No  A) doBaseStuff in Base can be marked public without causing errors
Yes B) doBaseStuff in Base can be marked private without causing errors
Yes C) doBaseStuff in Sub can be marked public without causing errors
Yes D) doBaseStuff in Sub can be marked protected without causing errors
No  E) doBaseStuff in Sub can be marked private without causing errors

Q5)
Y A) doOtherStuff in Sub can be marked private without causing errors
Y B) doOtherStuff in Sub can be marked public without causing errors
N C) doBaseStuff in Sub can be modified to return int without causing errors
Y D) doBaseStuff in Sub can be modified to take an int and return an int without causing errors
Y E) doBaseStuff in Sub can be modified to take an int and be private without causing errors

Q6)
Given:
public void q11A(int x) {
    x = x + 1;
}
And the fragment:

    int x = 99;
    q11A(x);
    System.out.println(x);

What is the result?
    A) 99
    B) 100
    C) An error

Q7)
Given
public void q12A(StringBuilder x) {
    x.append(" world");
}

And:
StringBuilder x = new StringBuilder("Hello");
q12A(x);
System.out.println(x);

What is the result?
    A) Hello
    B) Hello world
    C)  world
    D) An error

Q8)
  public void q14A(Integer x) {
    x = x + 1;
  }

    Integer x = 99;
    q14A(x);
    System.out.println(x);

What is the result?
    A) 99
    B) 100
    C) An error

Q9)
  public void q13A(int[] x) {
    x[0] = x[0] + 1;
  }

    int x[] = {99};
    q13A(x);
    System.out.println(x[0]);

What is the result?
    A) 99
    B) 100
    C) An error

Q10)
Q7)
Given
public void q12A(String x) {
    x = "Hello World!";
}

And:
String x = "Hello";
q12A(x);
System.out.println(x);

What is the result?
    A) Hello
    B) Hello world
    C)  world
    D) An error

Q11)
 class Base {
    void doBaseStuff() {
      System.out.println("doBaseStuff");
    }
  }
 class Sub extends Base {
    void doBaseStuff() {
      System.out.println("doSubStuff");
    }
    void doOtherStuff() {
      System.out.println("doOtherStuff");
    }
  }
    Base b = new Sub();
    b.doOtherStuff();

What is the result?
    A) doSubStuff
    B) doOtherStuff
    C) doBaseStuff
    D) Exception at runtime
    E) Compilation failure
 
12)
Given
void doStuff(Sub s) {
  Other x = (Other)s;
}

What is the result?
A) success
B) Compilation fails
C) Runtime Exception
D) Something else.

13)
Which are valid (i.e. compile...) individually

A) Predicate<String> ps = s -> s.length();
B) Predicate<String> ps = x => return x.length() > 3;
C) Predicate<Object> po = o -> o == "this";
D) Predicate<String> ps = (s) -> { x.length() < 2 };

14)
Which <n> are valid (i.e. compile...) individually (Choose n)
A) Predicate<Object> ps = s -> s.length() > 3;
Predicate<Object> requires "public boolean test(Object o)"
B) Predicate<String> ps = String s -> s.length() > 3; // needs parens round String s
C) Predicate<Object> po = (String s) -> { return s.length() < 4; }; // argument must be Object
D) Predicate<String> ps = (s) -> s.length() % 2 == 0 ? false : true;

// Side note :)
UnaryOperator<String> uos = s -> s.toUpperCase();

15)
Given:
String h1 = "Hello";
String h2 = new String("Hello");
String h3 = "Hello";
StringBuilder sb1 = new StringBuilder("Hello");
StringBuilder sb2 = new StringBuilder("Hello");

Which expressions are true?
A) h1 == h2
B) h1.equals(h2)
C) h1.equals(sb1)
D) h1 == h3
E) sb1.equals(sb2)

16)
Select all the valid answers 
void fun(int arr ...){ ... } 
a) fun( {1,2,3,} ) NO
b) fun( new int[]) NO
c) fun(new int {1,2,3}) NO
d) fun(1, 2, 3) YES

17)
  class Base {
    void doBaseStuff() {
      System.out.println("doBaseStuff");
    }
  }

  class Sub extends Base {
    void doBaseStuff() {
      System.out.println("doSubStuff");
    }

In the Base and Sub classes, which are true in isolation?
Y  A) doBaseStuff in Base can be marked throws Exception without causing errors
Y  B) doBaseStuff in Base can be marked throws RuntimeException without causing errors
N  C) doBaseStuff in Sub can be marked throws Exception without causing errors
Y  D) doBaseStuff in Sub can be marked throws RuntimeException without causing errors
Y  E) if doBaseStuff in Base were marked throws Exception,
       then doBaseStuff in Sub can be marked throws IOException without causing errors

18)
    StringBuilder sb1 = new StringBuilder("Hello");
    StringBuilder sb2 = sb1;
    sb1 = null;

    Which is true?
    A) sb1 is unreferenced and eligible for GC
    B) sb1 and sb2 are unreferenced and eligible for GC
    C) No objects are eligible for GC

19)
    StringBuilder sb1 = new StringBuilder("Hello");
    StringBuilder sb2 = new StringBuilder("World");
    sb1 = null;
    sb2 = sb1;

Which is true?
    A) Object containing "Hello" is unreferenced and eligible for GC
    B) Object containing "World" is unreferenced and eligible for GC
    C) Object containing "Hello", and "World" are both unreferenced and eligible for GC
    D) No objects are eligible for GC