answer 23)

4) the class can only access final variables

answer 24)

1) to call from the currently running thread to allow another thread of the same or higher priority to run

option 3 looks plausible but there is no guarantee that the thread that grabs the cpu time will be of a higher priority. it will depend on the threading algorithm of the java virtual machine and the underlying operating system

answer 25)

4) compilation and running with output 0 to 9

answer 26)

1) none of these options

because of the lack of a break statement after the break 10; statement the actual output will be

"ten" followed by "twenty"

answer 27)

4) system.gc();

answer 28)

1) compilation succeeds and at run time an output of 0 and false
the default value for a boolean declared at class level is false, and integer is 0;

answer 29)

1) compile time error

you will get an error saying something like "cant make a static reference to a non static variable". note that the main method is static. even if main was not static the array argv is local to the main method and would thus not be visible within amethod.

answer 30)

3) output of "not equal"

despite the actual character strings matching, using the == operator will simply compare memory location. because the one string was created with the new operator it will be in a different location in memory to the other string.