Java.lang Class

1

What two statements are true about the result obtained from calling Math.random()?

      1. The result is less than 0.0.

      2. The result is greater than or equal to 0.0..

      3. The result is less than 1.0.

      4. The result is greater than 1.0.

      5. The result is greater than or equal to 1.0.

A. 1 and 2
B. 2 and 3
C. 3 and 4
D. 4 and 5

2

Which of the following will produce an answer that is closest in value to a double, d, while 

not being greater than d?

A. (int)Math.min(d);
B. (int)Math.max(d);
C. (int)Math.abs(d);
D. (int)Math.floor(d);

3

Which two statements are true about wrapper or String classes?

      1. If x and y refer to instances of different wrapper classes, then the fragment x.equals(y) will 

          cause a compiler failure.

      2. If x and y refer to instances of different wrapper classes, then x == y can sometimes be true.

      3. If x and y are String references and if x.equals(y) is true, then x == y is true.

      4. If x, y, and z refer to instances of wrapper classes and x.equals(y) is true, and y.equals(z) is 

          true, then z.equals(x) will always be true.

      5. If x and y are String references and x == y is true, then y.equals(x) will be true.

A. 1 and 2
B. 2 and 3
C. 3 and 4
D. 4 and 5

4

Which statement is true given the following?

Double d = Math.random();

A. 0.0 < d <= 1.0
B. 0.0 <= d < 1.0
C. Compilation fail
D. Cannot say.

5

What will be the output of the program (in jdk1.6 or above)?

public class BoolTest 
{
    public static void main(String [] args) 
    {
        Boolean b1 = new Boolean("false");
        boolean b2;
        b2 = b1.booleanValue();
        if (!b2) 
        {
            b2 = true;
            System.out.print("x ");
        }
        if (b1 & b2) /* Line 13 */
        {
            System.out.print("y ");
        }
        System.out.println("z");
    }
}
A. z
B. x z
C. y z
D. Compilation fails.