public class X { public object m （） { object o = new float （3.14F）； object oa = new object [1]； oa[0]= o； o = null； oa[0] = null； return o； } } When is the float object created in line 3， eligible for garbage collection？（） A、 Just after line 5.B、 Just after line 6.C、 Just after line 7.D、 Just after line 8（that is， as the method returns）.
public class X { public object m （） { object o = new float （3.14F）； object oa = new object [1]； oa[0]= o； o = null； oa[0] = null； return o； } } When is the float object created in line 3， eligible for garbage collection？（）
- A、 Just after line 5.
- B、 Just after line 6.
- C、 Just after line 7.
- D、 Just after line 8（that is， as the method returns）.
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试题六（共 15分）阅读以下说明和Java代码，将应填入 （n） 处的字句写在答题纸的对应栏内。【说明】已知类 LinkedList 表示列表类，该类具有四个方法：addElement()、lastElement()、umberOfElement()以及removeLastElement()。四个方法的含义分别为：void addElement(Object): 在列表尾部添加一个对象；Object lastElement(): 返回列表尾部对象；int numberOfElement(): 返回列表中对象个数；void removeLastElement(): 删除列表尾部的对象。现需要借助LinkedList来实现一个Stack栈类， Java代码1和Java代码2分别采用继承和组合的方式实现。【Java代码1】public class Stack extends LinkedList{public void push(Object o){ //压栈addElement(o);}public Object peek(){ //获取栈顶元素return （1） ;}public boolean isEmpty(){ //判断栈是否为空return numberOfElement() == 0;}public Object pop(){ //弹栈Object o = lastElement();（2） ;return o;}}【Java代码2】public class Stack {private （3） ;public Stack(){list = new LinkedList();}public void push(Object o){list.addElement(o);}public Object peek(){//获取栈顶元素return list. （4） ;}public boolean isEmpty(){//判断栈是否为空return list.numberOfElement() == 0;}public Object pop(){ //弹栈Object o = list.lastElement();list.removeLastElement();return o;}}【问题】若类LinkedList新增加了一个公有的方法removeElement(int index)，用于删除列表中第index个元素，则在用继承和组合两种实现栈类Stack的方式中，哪种方式下Stack对象可访问方法removeElement(int index)？ （5） （A. 继承 B. 组合）
1.public class GC{2.private Objec to；3.private void doSomethingElse（Object obj）{o=obj；}4.public void doSomething（）{5.Object o=new Object（）；6.doSomethingElse（o）；7.o=new Object（）；8.doSomethingElse（null）；9.o=null；10.}11.}When the doSomething method is called，after which line does the Object created in line 5 become available for garbage collection？（）A.Line5B.Line6C.Line7D.Line8E.Line9F.Line10
11.class Snoochy{12.Boochybooch；13.public Snoochy（）{booch=newBoochy（this）；}14.}15.16.class Boochy{17.Snoochy snooch；18.public Boochy（Snoochys）{snooch=s；}19.}And the statements：21.public static void main（String[]args）{22.Snoochy snoog=new Snoochy（）；23.snoog=null；24.//more code here25.}Which statement is true about the objects referenced by snoog，snooch，and booch immediately after line 23 executes？（）A.None of these objects are eligible for garbage collection.B.Only the object referenced by booch is eligible for garbage collection.C.Only the object referenced by snoog is eligible for garbage collection.D.Only the object referenced by snooch is eligible for garbage collection.E.The objects referenced by snooch and booch are eligible for garbage collection.
publicclassX{2.publicobjectm(){3.objecto=newfloat(3.14F);4.object[]oa=newobject[1];5.oa[0]=o;6.o=null;7.oa[0]=null;10.returno;9.}10.}Whenisthefloatobjectcreatedinline3,eligibleforgarbagecollection?() A.Justafterline5.B.Justafterline6.C.Justafterline7.D.Justafterline8（thatis，asthemethodreturns）.
publicclassX(2.publicobjectm(){3.objecto=newfloat(3.14F);4.object[]oa=newobject[1];5.oa[0]=o;6.o=null;7.returnoa[0];8.}9.}Whenisthefloatobjectcreatedinline3,eligibleforgarbagecollection?() A.Justafterline5B.Justafterline6C.Justafterline7（thatis，asthemethodreturns）D.Neverinthismethod.
publicObjectm(){11.Objecto=newFloat(3.14F);12.Object[]oa=newObject[1];13.oa[0]=o;14.o=null;15.returnoa[0];16.}WhenistheFloatobject,createdinline11,eligibleforgarbagecollection?() A.Justafterline13.B.Justafterline14.C.Neverinthismethod.D.Justafterline15（thatis，asthemethodreturns）.
阅读以下说明和Java代码，将应填入(n)处的字句写在答题纸的对应栏内。说明类Queue表示队列，类中的方法如下表所示。类Node表示队列中的元素；类EmptyQueueException 给出了队列操作中的异常处理操作。Java 代码public class TestMain{ // 主类public static void main(String args[]) {Queue q = new Queue();q.enqueue("first!");q.enqueue("second!");q.enqueue("third!");(1) {while(true)System.out.println(q. dequeue());}catch((2)) ( }}}public class Queue { // 队列Node m_FirstNode;public Queue() { m_FirstNode = null; }public boolean isEmpty() {if(m_FirstNode == null) return true;else return false;}public void enqueue(Object newNode) {// 入队操作Node next = m_FirstNode;if(next==null) m_FirstNode = new Node(newNode);else {while(next.getNext() != null) next = next.getNext();next.setNext(new Node(newNode));}}public Object dequeue() (3) {// 出队操作Object node;if (isEmpty())(4); // 队列为空，抛出异常else {node = m_FirstNode.getObject();m_FirstNode = m_FirstNode.getNext();return node;}}}public class Node { // 队列中的元素Object m_Data;Node m_Next;public Node(Object data) { m_Data = data; m_Next = null; }public Node(Object data, Node next) { m_Data = data; m_Next = next; }public void setObject(Object data) { m_Data = data; }public Object getObject0 { return m_Data; }public void setNext(Node next) { m_Next = next; }public Node getNext() { return m_Next; }}public class EmptyQueueException extends (5) { // 异常处理类public EmptyQueueException0 {System.out.println("队列已空 ! ");}}
public class X { public object m （） { object o = new float （3.14F）； object oa = new object [1]； oa[0]= o； o = null； return oa[0]； } } When is the float object created in line 3， eligible for garbage collection？（）A、 Just after line 5B、 Just after line 6C、 Just after line 7 （that is， as the method returns）D、 Never in this method.
1. class TestA { 2. TestB b； 3. TestA（） { 4. b = new TestB（this）； 5. } 6. } 7. class TestB { 8. TestA a； 9. TestB（TestA a） { 10. this.a = a； 11. } 12. } 13. class TestAll { 14. public static void main （String args[]） { 15. new TestAll（）.makeThings（）； 16. // ...code continues on 17. } 18. void makeThings（） { 19. TestA test = new TestA（）； 20. } 21. } Which two statements are true after line 15， before main completes？（）A、 Line 15 causes a stack overflow.B、 An exception is thrown at runtime.C、 The object referenced by a is eligible for garbage collection.D、 The object referenced by b is eligible for garbage collection.E、 The object referenced by a is not eligible for garbage collection.F、 The object referenced by b is not eligible for garbage collection.
public class Test { public static void main （String args） { class Foo { public int i = 3； } Object o = （Object） new Foo（）； Foo foo = （Foo）o； System.out.printIn（foo. i）； } } What is the result？（） A、 Compilation will fail.B、 Compilation will succeed and the program will print “3”C、 Compilation will succeed but the program will throw a ClassCastException at line 6.D、 Compilation will succeed but the program will throw a ClassCastException at line 7.
10. public Object m（） { 11. Object o = new Float（3.14F）； 12. Object [] oa = new Object[1]； 13. oa[0] = o； 14. o = null； 15. return oa[0]； 16. } When is the Float object， created in line 11， eligible for garbage collection？（） A、 Just after line 13.B、 Just after line 14.C、 Never in this method.D、 Just after line 15 （that is， as the method returns）.
12. void start（） { 13. A a = new A（）； 14. B b = new B（）； 15. a.s（b）； 16. b = null； 17. a = null； 18. System.out.println（“start completed”）； 19. } When is the B object， created in line 14， eligible for garbage collection？（） A、 After line 16.B、 After line 17.C、 After line 18 （when the methods ends）.D、 There is no way to be absolutely certain.E、 The object is NOT eligible for garbage collection.
1. public class GC { 2. private Object o； 3. private void doSomethingElse（Object obj） { o = obj； } 4. public void doSomething（） { 5. Object o = new Object（）； 6. doSomethingElse（o）； 7. o = new Object（）； 8. doSomethingElse（null）； 9.o=null； 10. } 11. } When the doSomething method is called， after which line does the Object created in line 5 become available for garbage collection？（） A、 Line 5B、 Line 6C、 Line 7D、 Line 8E、 Line 9F、 Line 10
1.public class GC{ 2.private Objec to； 3.private void doSomethingElse（Object obj）{o=obj；} 4.public void doSomething（）{ 5.Object o=new Object（）； 6.doSomethingElse（o）； 7.o=new Object（）； 8.doSomethingElse（null）； 9.o=null； 10.} 11.} When the doSomething method is called，after which line does the Object created in line 5 become available for garbage collection？（）A、Line5B、Line6C、Line7D、Line8E、Line9F、Line10
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. return oa[0]； 8. } 9. } When is the float object created in line 3， eligible for garbage collection？（） A、 Just after line 5B、 Just after line 6C、 Just after line 7 （that is， as the method returns）D、 Never in this method.
public class Test { public static void main（String args[]） { class Foo { public int i = 3； } Object o = （Object）new Foo（）； Foo foo = （Foo）o； System.out.println（“i = “ + foo.i）； } } What is the result？（） A、 i = 3B、 Compilation fails.C、 A ClassCastException is thrown at line 6.D、 A ClassCastException is thrown at line 7.
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？（） A、 Just after line 5.B、 Just after line 6.C、 Just after line 7.D、 Just after line 8（that is， as the method returns）.
Which three will compile and run without exception？（）A、private synchronized Object o；B、void go（）{ synchronized（）{/* code here */}C、public synchronized void go（）{/* code here */}D、private synchronized（this） void go（）{/* code here */}E、void go（）{ synchronized（Object.class）{/* code here */}F、void go（）{ Object o = new Object（）； synchronized（o）{/* code here */}
11. class Snoochy { 12. Boochybooch； 13. public Snoochy（） { booch = new Boochy（this）； } 14. } 15. 16. class Boochy { 17. Snoochy snooch； 18. public Boochy（Snoochy s） { snooch = s； } 19. } And the statements： 21. public static void main（String[] args） { 22. Snoochy snoog = new Snoochy（）； 23. snoog = null； 24. // more code here 25. } Which statement is true about the objects referenced by snoog， snooch， and booch immediately after line 23 executes？（） A、 None of these objects are eligible for garbage collection.B、 Only the object referenced by booch is eligible for garbage collection.C、 Only the object referenced by snoog is eligible for garbage collection.D、 Only the object referenced by snooch is eligible for garbage collection.E、 The objects referenced by snooch and booch are eligible for garbage collection.
单选题1.public class GC{ 2.private Objec to； 3.private void doSomethingElse（Object obj）{o=obj；} 4.public void doSomething（）{ 5.Object o=new Object（）； 6.doSomethingElse（o）； 7.o=new Object（）； 8.doSomethingElse（null）； 9.o=null； 10.} 11.} When the doSomething method is called，after which line does the Object created in line 5 become available for garbage collection？（）ALine5BLine6CLine7DLine8ELine9FLine10
单选题11. class Snoochy { 12. Boochybooch； 13. public Snoochy（） { booch = new Boochy（this）； } 14. } 15. 16. class Boochy { 17. Snoochy snooch； 18. public Boochy（Snoochy s） { snooch = s； } 19. } And the statements： 21. public static void main（String[] args） { 22. Snoochy snoog = new Snoochy（）； 23. snoog = null； 24. // more code here 25. } Which statement is true about the objects referenced by snoog， snooch， and booch immediately after line 23 executes？（）A None of these objects are eligible for garbage collection.B Only the object referenced by booch is eligible for garbage collection.C Only the object referenced by snoog is eligible for garbage collection.D Only the object referenced by snooch is eligible for garbage collection.E The objects referenced by snooch and booch are eligible for garbage collection.
单选题public class Test { public static void main（String args[]） { class Foo { public int i = 3； } Object o = （Object）new Foo（）； Foo foo = （Foo）o； System.out.println（“i = “ + foo.i）； } } What is the result？（）A i = 3B Compilation fails.C A ClassCastException is thrown at line 6.D A ClassCastException is thrown at line 7.
单选题public class X { public object m （） { object o = new float （3.14F）； object oa = new object [1]； oa[0]= o； o = null； oa[0] = null； return o； } } When is the float object created in line 3， eligible for garbage collection？（）A Just after line 5.B Just after line 6.C Just after line 7.D Just after line 8（that is， as the method returns）.
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？（）A Just after line 5.B Just after line 6.C Just after line 7.D Just after line 8（that is， as the method returns）.
单选题public class X { public object m （） { object o = new float （3.14F）； object oa = new object [1]； oa[0]= o； o = null； return oa[0]； } } When is the float object created in line 3， eligible for garbage collection？（）A Just after line 5B Just after line 6C Just after line 7 （that is， as the method returns）D Never in this method.
单选题12. void start（） { 13. A a = new A（）； 14. B b = new B（）； 15. a.s（b）； 16. b = null； 17. a = null； 18. System.out.println（“start completed”）； 19. } When is the B object， created in line 14， eligible for garbage collection？（）A After line 16.B After line 17.C After line 18 （when the methods ends）.D There is no way to be absolutely certain.E The object is NOT eligible for garbage collection.
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. return oa[0]； 8. } 9. } When is the float object created in line 3， eligible for garbage collection？（）A Just after line 5B Just after line 6C Just after line 7 （that is， as the method returns）D Never in this method.