Computer Knowledge

Java Core Classes and Threads

1,473 Questions

Java core classes and threads form the foundation of object oriented programming and are crucial for IT officer and programming exams. This includes concepts like string mutability, collections, and multithreading. Solve these questions to test your practical coding and theoretical knowledge.

String and StringBuffer classesThread execution methodsJava collections frameworkCharacter streams input outputVariable serialization rules

Java Core Classes and Threads Questions

Multiple choice

public class Test2 { public static int x; public static int foo(int y) { return y * 2; } public static void main(String [] args) { int z = 5; assert z > 0; /* Line 11 / assert z > 2: foo(z); / Line 12 / if ( z < 7 ) assert z > 4; / Line 14 */

switch (z) { case 4: System.out.println("4 "); case 5: System.out.println("5 "); default: assert z < 10; }

if ( z < 10 ) assert z > 4: z++; /* Line 22 */ System.out.println(z); } }

Which line is an example of an inappropriate use of assertions?

  1. Line 11

  2. Line 12

  3. Line 14

  4. Line 22
Reveal answer Fill a bubble to check yourself
D Correct answer
Explanation

Assert statements should not cause side effects. Line 22 changes the value of z if the assert statement is false. Option A is fine; a second expression in an assert statement is not required. Option B is fine because it is perfectly acceptable to call a method with the second expression of an assert statement. Option C is fine because it is proper to call an assert statement conditionally.