Compilation of class A fails.
Line 28 prints the value 3 to System.out.
Line 28 prints the value 1 to System.out.
Compilation fails because of an error on line 28.
A runtime error occurs when line 25 executes.
第1题:
A.The application will crash.
B.The code on line 29 will be executed.
C.The code on line 5 of class A will execute.
D.The code on line 5 of class B will execute.
E.The exception will be propagated back to line 27.
第2题:
public class Threads5 { public static void main (String[] args) { new Thread(new Runnable() { public void run() { System.out.print(”bar”); } }).start(); } } What is the result?()
第3题:
A.Compilation fails.
B.ClassC is displayed.
C.The code runs with no output.
D.An exception is thrown at runtime.
第4题:
1. public class A { 2. public void method1() { 3. B b=new B(); 4. b.method2(); 5. // more code here 6. } 7. } 1. public class B { 2. public void method2() { 3.C c=new C(); 4. c.method3(); 5. // more code here 6. } 7. } 1. public class C { 2. public void method3() { 3. // more code here 4. } 5. } Given: 25. try { 26. A a=new A(); 27. a.method1(); 28. } catch (Exception e) { 29. System.out.print(”an error occurred”); 30. } Which two are true if a NullPointerException is thrown on line 3 of class C?()
第5题:
class A { public A() { System.out.println(“hello from a”); } } class B extends A { public B () { System.out.println(“hello from b”); super(); } } public class Test { public static void main(String args[]) { A a = new B(); } } What is the result when main is executed?()
第6题:
public class Threads3 implements Runnable { public void run() { System.out.print(”running”); } public static void main(String[] args) { Thread t = new Thread(new Threads3()); t.run(); t.run(); t.start(); } } What is the result?()
第7题:
10. interface A { void x(); } 11. class B implements A { public void x() { } public voidy() { } } 12. class C extends B { public void x() {} } And: 20. java.util.List list = new java.util.ArrayList(); 21. list.add(new B()); 22. list.add(new C()); 23. for (A a:list) { 24. a.x(); 25. a.y();; 26. } What is the result?()
第8题:
A.Line 26 prints "a" to System.out.
B.Line 26 prints "b" to System.out.
C.An exception is thrown at line 26 at runtime.
D.Compilation of class A will fail due to an error in line 6.
第9题:
23. Object [] myObjects = { 24. new integer(12), 25. new String(”foo”), 26. new integer(5), 27. new Boolean(true) 28. }; 29. Arrays.sort(myObjects); 30. for( int i=0; i
第10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?()