short circuit operators

[velan vel]

hai
can any one explain the question

1. public class Test {
2. public static void main(String [] args) {
3. System.out.println(args.length > 4 &&
4. args[4].equals("-d"));
5. }
6. }
f the program is invoked using the command line:
java Test One Two Three -d
What is the result?
A. true
B. false
C. Compilation fails.
D. An exception is thrown at runtime.

by
velan vel

[Krishnan Loganathan]

Hi Velan,

The output will be 'B' - false

Regards,
Loga

[Abhinav Gogna]

Actually the output is true.

The first part of the comparison (System.out.println(args.length > 4) returns true as we have 5 values in args
1) Test
2) One
3) Two
4) Three
5) -d

for the second comparison (args[4].equals("-d")), the value is true, since args @ 4th place (counting from 0) is "-d". Although "-d" is fifth but arrays start counting from 0. Hence the && operator will return as both the conditions are "True".

[santosh kothapalli]

Hi Velan,
The result is false
Explaination:
As u are use conditional operator && and the first expression args.length > 4 is evaluated to false,so it does not evaluate the second expression args[4].equals("-d").
If the first expression evaluates to true by changing to args.length==4 this evaluates to true and the second expression is evaluated which results in ArrayIndexOutOfBoundsException.

cheers,
Santosh

[santosh kothapalli]

Originally posted by Abhinav Gogna:
Actually the output is true.

The first part of the comparison (System.out.println(args.length > 4) returns true as we have 5 values in args
1) Test
2) One
3) Two
4) Three
5) -d

for the second comparison (args[4].equals("-d")), the value is true, since args @ 4th place (counting from 0) is "-d". Although "-d" is fifth but arrays start counting from 0. Hence the && operator will return as both the conditions are "True".

Abhinav,
Test is the name of the program and not the Argument.

[vinod awar]

the answer is false.
&& is shortcircuit operator.once the first condition is evaluated as fasle
it will not check the second condition.
args>4 is false because only commandline parameters are passed