单项选择题
A. Compilation fails.
B. An exception is thrown at runtime.
C. The variable first is set to null.
D. The variable first is set to elements[0].
单项选择题 11. class Cup { } 12. class PoisonCup extends Cup { } 21. public void takeCup(Cup c) { 22. if(c instanceof PoisonCup) { 23. System.out.println(”Inconceivable!”); 24. } else if(c instanceof Cup) { 25. System.out.println(”Dizzying intellect!”); 26. } else { 27. System.exit(0); 28. } 29. } And the execution of the statements: Cup cup = new PoisonCup(); takeCup(cup); What is the output?()
多项选择题 10. public class MyClass { 11. 12. public Integer startingI; 13. public void methodA() { 14. Integer i = new Integer(25); 15. startingI = i; 16. methodB(i); 17. } 18. private void methodB(Integer i2) { 19. i2 = i2.intValue(); 20. 21. } 22. } If methodA is invoked, which two are true at line 20?()
单项选择题 public static void test(String str) { int check = 4; if (check = str.length()) { System.out.print(str.charAt(check -= 1) +“, “); } else { System.out.print(str.charAt(0) + “, “); } } and the invocation: test(”four”); test(”tee”); test(”to”); What is the result?()