10. public class Bar { 11.static void foo(int...x) { 12. // insert code here 13. } 14. } Which two code fragments, inserted independently at line 12, will allow the class to compile?()
单选题1. public class X { 2. public object m () { 3. object o = new float (3.14F); 4. object [] oa = new object [1]; 5. oa[0]= o; 6. o = null; 7. oa[0] = null; 10. return o; 9. } 10. } When is the float object created in line 3, eligible for garbage collection?()AJust after line 5.BJust after line 6.CJust after line 7.DJust after line 8(that is, as the method returns).
点击查看答案
多选题Given: 10. interface Jumper { public void jump(); } ... 20. class Animal {} ... 30. class Dog extends Animal { 31. Tail tail; 32. } ... 40. class Beagle extends Dog implements Jumper{ 41. public void jump() {} 42. } ... 50. class Cat implements Jumper{ 51. public void jump() {} 52. }. Which three are true?()ACat is-a JumperBCat is-a AnimalCDog is-a JumperDDog is-a AnimalEBeagle has-a JumperFCat has-a AnimalGBeagle has-a Tail
单选题1. public class A { 2. public void doit() { 3. } 4. public String doit() { 5. return “a”; 6. } 7. public double doit(int x) { 8. return 1.0; 9. } 10.} What is the result?()AAn exception is thrown at runtime.BCompilation fails because of an error in line 7.CCompilation fails because of an error in line 4.DCompilation succeeds and no runtime errors with class A occur.
单选题10. interface Foo { int bar(); } 11. public class Sprite { 12. public int fubar( Foo foo) { return foo.bar(); } 13. public void testFoo() { 14. fubar( 15. // insert code here 16.); 17. } 18. } Which code, inserted at line 15, allows the class Sprite to compile?()AFoo { public int bar() { return 1; } }Bnew Foo { public int bar() { return 1; } }CnewFoo() { public int bar(){return 1; } }Dnew class Foo { public int bar() { return 1; } }
单选题1. public class Outer{ 2. public void someOuterMethod() { 3. // Line 3 4. } 5. public class Inner{} 6. public static void main( String[]argv ) { 7. Outer o = new Outer(); 8. // Line 8 9. } 10. } Which instantiates an instance of Inner?()Anew Inner(); // At line 3Bnew Inner(); // At line 8Cnew o.Inner(); // At line 8Dnew Outer.Inner(); // At line 8
单选题1. public class SimpleCalc { 2. public int value; 3. public void calculate() { value += 7; } 4. } And: 1. public class MultiCalc extends SimpleCalc { 2. public void calculate() { value -= 3; } 3. public void calculate(int multiplier) { 4. calculate(); 5. super.calculate(); 6. value *=multiplier; 7. } 8. public static void main(String[] args) { 9. MultiCalc calculator = new MultiCalc(); 10. calculator.calculate(2); 11. System.out.println(”Value is: “+ calculator.value); 12. } 13. } What is the result?()AValue is: 8BCompilation fails.CValue is: 12DValue is: -12EThe code runs with no output.FAn exception is thrown at runtime.
单选题10. class Line { 11. public class Point { public int x,y; } 12. public Point getPoint() { return new Point(); } 13. } 14. class Triangle { 15. public Triangle() { 16. // insert code here 17. } 18. } Which code, inserted at line 16, correctly retrieves a local instance of a Point object?()APoint p = Line.getPoint();BLine.Point p = Line.getPoint();CPoint p = (new Line()).getPoint();DLine.Point p = (new Line()).getPoint();