Java Programming :: Flow Control

1.public void foo( boolean a, boolean b)
{
if( a )
{
System.out.println("A"); /* Line 5 */
}
else if(a && b) /* Line 7 */
{
System.out.println( "A && B");
}
else /* Line 11 */
{
if ( !b )
{
System.out.println( "notB") ;
}
else
{
System.out.println( "ELSE" ) ;
}
}
}

A. If a is true and b is true then the output is "A && B"
B. If a is true and b is false then the output is "notB"
C. If a is false and b is true then the output is "ELSE"
D. If a is false and b is false then the output is "ELSE"
Answer & Explanation

Answer: Option C

Explanation:

Option C is correct. The output is "ELSE". Only when a is false do the output lines after 11 get some chance of executing.

Option A is wrong. The output is "A". When a is true, irrespective of the value of b, only the line 5 output will be executed. The condition at line 7 will never be evaluated (when a is true it will always be trapped by the line 12 condition) therefore the output will never be "A && B".

Option B is wrong. The output is "A". When a is true, irrespective of the value of b, only the line 5 output will be executed.

Option D is wrong. The output is "notB".

2.switch(x)
{
default:
System.out.println("Hello");
}

Which two are acceptable types for x?

byte
long
char
float
Short
Long

A. 1 and 3 B. 2 and 4
C. 3 and 5 D. 4 and 6
Answer & Explanation

Answer: Option A

Explanation:

Switch statements are based on integer expressions and since both bytes and chars can implicitly be widened to an integer, these can also be used. Also shorts can be used. Short and Long are wrapper classes and reference types can not be used as variables.