1.Which statement about the garbage collection mechanism are true? A. Garbage collection require additional PRograme code in cases where multiple threads are running. B. The programmer can indicate that a reference through a local variable is no longer of interest. C. The programmer has a mechanism that eXPlicity and immediately frees the memory used by java objects. D. The garbage collection mechanism can free the memory used by Java Object at explection time. E. The garbage collection system never reclaims memory from objects while are still accessible to running user threads.
2. Give the following method: 1) public void method( ){ 2) String a,b; 3) a=new String(“hello world”); 4) b=new String(“game over”); 5) System.out.println(a+b+”ok”); 6) a=null; 7) a=b; 8) System.out.println(a); 9) } In the absence of compiler optimization, which is the earliest point the object a refered is definitely elibile to be garbage collection. A. before line 3 B.before line 5 C. before line 6 D.before line 7 E. Before line 9
3. In the class java.awt.AWTEvent,which is the parent class upon which jdk1.1 awt events are based there is a method called getID which phrase accurately describes the return value of this method? A. It is a reference to the object directly affected by the cause of the event. B. It is an indication of the nature of the cause of the event. C. It is an indication of the position of the mouse when it caused the event. D. In the case of a mouse click, it is an indication of the text under the mouse at the time of the event. E. It tells the state of certain keys on the keybord at the time of the event. F. It is an indication of the time at which the event occurred.
4. Which statement about listener is true? A. Most component allow multiple listeners to be added. B. If multiple listener be add to a single component, the event only affected one listener. C. Component don?t allow multiple listeners to be add. D. The listener mechanism allows you to call an addXxxxListener method as many times as is needed, specifying as many different listeners as your design require.
5.Give the following code: public class Example{ public static void main(String args[] ){ int l=0; do{ System.out.println(“Doing it for l is:”+l); }while(--l>0) System.out.println(“Finish”); } } Which well be output: A. Doing it for l is 3 B. Doing it for l is 1 C. Doing it for l is 2 D. Doing it for l is 0 E. Doing it for l is ?C1 F. Finish
6. Give the code fragment: 1) switch(x){ 2) case 1:System.out.println(“Test 1”);break; 3) case 2: 4) case 3:System.out.println(“Test 2”);break; 5) default:System.out.println(“end”); 6) } which value of x would cause “Test 2” to the output: A. 1 B. 2 C. 3 D. default
7. Give incompleted method: 1) 2) { if(unsafe()){//do something…} 3) else if(safe()){//do the other…} 4) } The method unsafe() well throe an IOException, which completes the method of declaration when added at line one? A. public IOException methodName() B. public void methodName() C. public void methodName() throw IOException D. public void methodName() throws IOException E. public void methodName() throws Exception
8. Give the code fragment: if(x>4){ System.out.println(“Test 1”);} else if (x>9){ System.out.println(“Test 2”);} else { System.out.println(“Test 3”);} Which range of value x would prodUCe of output “Test 2”? A. x<4 B. x>4 C. x>9 D. None
9. Give the following method: public void example(){ try{ unsafe(); System.out.println(“Test1”); }catch(SafeException e){System.out.println(“Test 2”); }finally{System.out.println(“Test 3”);} System.out.println(“Test 4”); Which will display if method unsafe () run normally? A. Test 1 B. Test 2 C. Test 3 D. Test 4
10. Which method you define as the starting point of new thread in a class from which new the thread can be excution? A. public void start() B. public void run() C. public void int() D. public static void main(String args[]) E. public void runnable()
11.Given the following class definition: class A{ protected int i; A(int i){ this.i=i; } } which of the following would be a valid inner class for this class? Select all valid answers: A. class B{ } B. class B extends A{ } C. class B extends A{ B(){System.out.println(“i=”+i);} } D. class B{ class A{} } E. class A{}
12. Which modifier should be applied to a method for the lock of object this to be oBTained prior to excution any of the method body? A. synchronized B. abstract C. final D. static E. public
13. The following code is entire contents of a file called Example.java,causes precisely one error during compilation: 1) class SubClass extends BaseClass{ 2) } 3) class BaseClass(){ 4) String str; 5) public BaseClass(){ 6) System.out.println(“ok”);} 7) public BaseClass(String s){ 8) str=s;}} 9) public class Example{ 10) public void method(){ 11) SubClass s=new SubClass(“hello”); 12) BaseClass b=new BaseClass(“world”); 13) } 14) }
Which line would be cause the error? A. 9 B. 10 C. 11 D.12
14. Which statement is correctly declare a variable a which is suitable for refering to an array of 50 string empty object? A. String [] a B. String a[] C. char a[][] D. String a[50] F. Object a[50]
15. Give the following java source fragement: //point x public class Interesting{ //do something } Which statement is correctly Java syntax at point x? A. import java.awt.*; B.package mypackage C. static int PI=3.14 D. public class MyClass{//do other thing…} E. class MyClass{//do something…}
16. Give this class outline: class Example{ private int x; //rest of class body… } Assuming that x invoked by the code java Example, which statement can made x be directly accessible in main() method of Example.java? A. Change private int x to public int x B. change private int x to static int x C. Change private int x to protected int x D. change private int x to final int x
17. the piece of preliminary analsis work describes a class that will be used frequently in many unrelated parts of a project “The polygon object is a drawable, A polygon has vertex information stored in a vector, a color, length and width.” Which Data type would be used? A. Vector B. int C. String D. Color E. Date
18. A class design requires that a member variable should be accessible only by same package, which modifer Word should be used? A. protected B. public C. no modifer D. private
19.Which declares for native method in a java class corrected? A. public native void method(){} B. public native void method(); C. public native method(); D. public void method(){native;} E. public void native method();
20. Which modifer should be applied to a declaration of a class member variable for the value of variable to remain constant after the creation of the object?
21. Which is the main() method return of a application? A. String B. byte C. char D. void
22. Which is corrected argument of main() method of application? A. String args B. String ar[] C. Char args[][] D. StringBuffer arg[]
23. “The Employee object is a person, An Employee has appointment store in a vector, a hire date and a number of dependent” short answer: use shortest statement declare a class of Employee.
24. Give the following class defination inseparate source files: public class Example{ public Example(){//do something} protected Example(int i){//do something} protected void method(){//do something} } public class Hello extends Example{//member method and member variable} Which methods are corrected added to the class Hello? A. public void Example(){} B. public void method(){} C. protected void method(){} D. private void method(){}
25. Float s=new Float(0.9F); Float t=new Float(0.9F); Double u=new Double(0.9); Which expression?s result is true? A. s==t B. s.equals(t) C. s==u D. t.equals(u)
26. Give following class: class AClass{ private long val; public AClass(long v){val=v;} public static void main(String args[]){ AClass x=new AClass(10L); AClass y=new AClass(10L); AClass z=y; long a=10L; int b=10; } } Which expression result is true? A. a==b; B. a==x; C. y==z; D. x==y; E. a==10.0;
27. A socket object has been created and connected to a standard internet service on a remote network server. Which construction give the most suitable means for reading ASCII data online at a time from the socket? A. InputStream in=s.getInputStream(); B. DataInputStream in=new DataInputstream(s.getInputStream()); C. ByteArrayInputStream in=new ByteArrayInputStream(s.getInputStream()); D. BufferedReader in=new BufferedReader(new InputStreamReader(s.getInputStream())); E. BufferedReader in=new BufferedReader(new InputStreamReader(s.getInputStream()),”8859-1”);
28. String s=”Example String”; Which Operation is legal? A. s>>>=3; B. int i=s.length(); C. s[3]=”x”; D. String short_s=s.trim(); E. String t=”root”+s;
29. What happens when you try to compile and run the following program? class Mystery{ String s; public static void main(String[] args){ Mystery m=new Mystery(); m.go(); } void Mystery(){ s=”constructor”; } void go(){ System.out.println(s); } } A. this code will not compile B. this code compliles but throws an exception at runtime C. this code runs but nothing appears in the standard output D. this code runs and “constructor” in the standard output E. this code runs and writes ”null” in the standard output
30. What use to position a Button in a Frame ,only width of Button is affected by the Frame size, which Layout Button well be set ? A. FlowLayout; B. GridLayout; C. North of BorderLayout D. South of BorderLayout E. East or West of BorderLayout
31. What use to position a Button in a Frame, size of Button is not affected by the Frame size, which Layout Button will be set? A. FlowLayout; B. GridLayout; C. North of BorderLayout D. South of BorderLayout E. East or West of BorderLayout
32. An AWT GUI under exposure condition, which one or more method well be invoke when it redraw? A. paint(); B. update(); C. repaint(); D. drawing();
33. Select valid identifier of Java: A. userName B. %passwd C. 3d_game D. $charge E. this
34. Which are Java keyword? A. goto B. null C. FALSE D. native E. const
35. Run a corrected class: java ?Ccs AClass a b c <enter> Which statement is true? A. args[0]=”-cs”; B. args[1]=”a b c”; C. args[0]=”java”; D. args[0]=”a”; E. args[1]=?b?
36. Give the following java class: public class Example{ static int x[]=new int[15]; public static void main(String args[]){ System.out.println(x[5]); } } Which statement is corrected? A. When compile, some error will occur. B. When run, some error will occur. C. Output is zero. D. Output is null.
37. Give the following java class: public class Example{ public static void main(String args[]){ static int x[] = new int[15]; System.out.println(x[5]); } } Which statement is corrected? A. When compile, some error will occur. B. When run, some error will occur. C. Output is zero. D. Output is null.
38. Short answer: The decimal value of i is 12, the octal i value is:
39. Short answer: The decimal value of i is 7, the hexadecimal i value is:
40. Which is the range of char? A. 27~27-1 B. 0~216-1 C. 0~216 D. 0~28
41. Which is the range of int type? A. -216~216-1 B.- 231~231-1 C. -232~232-1 D. -264~264-1
42. Give the following class: public class Example{ String str=new String(“good”); char ch[]={ public static void main(String args[]){ Example ex=new Example(); ex.change(ex.str,ex.ch); System.out.println(ex.str+”and”+ex.ch); } public void change(String str,char ch[]){ str=”test ok”;ch[0]=?g? } } Which is the output: A. good and abc B. good and gbc C. test ok and abc D. test ok and gbc
43. Which code fragments would correctly identify the number of arguments passed via command line to a Java application, exclude the name of the class that is being invoke. A. int count = args.length; B. int count = args.length-1; C. int count=0; while(args[count]!=null) count++; D. int count=0;while (!(args[count].equals(“”))) count++;
44. FilterOutputStream is the parent class for BufferedOutputStream, DataOutputStream and PrintStream. Which classes are valid argument for the constructor of a FilterOutputStream? A. InputStream B. OutputStream C. File D. RandomAccessFile E. StreamTokenizer
45. Given a TextArea using a proportional pitch font and constructed like this: TextArea t=new TextArea(“12345”,5,5); Which statement is true? A. The displayed width shows exactly five characters one each line unless otherwise constrained B. The displayed height is five lines unless otherwise constrained C. The maximum number of characters in a line will be five D. The user will be able to edit the character string E. The displayed string can use multiple fonts
46. Given a List using a proportional pitch font and constructed like this: List l=new List(5,true); Which statement is true? A. The displayed item exactly five lines unless otherwise constrained B. The displayed item is five lines init, but can displayed more than five Item by scroll C. The maximum number of item in a list will be five. D. The list is multiple mode
47. Given this skeleton of a class currently under construction: public class Example{ int x,y,z;
public Example (int a, int b) { //lots of complex computation x=a; y=b; } public Example(int a, int b, int c){ // do everything the same as single argument // version of constructor // including assignment x=a, y=b, z=c z=c; } } What is the most concise way to code the “do everything…” part of the constructor taking two arguments? Short answer:
48. Which correctly create a two dimensional array of integers? A. int a[][] = new int[][]; B. int a[10][10] = new int[][]; C. int a[][] = new int[10][10]; D. int [][]a = new int[10][10]; E. int []a[] = new int[10][10];
49. Which are correct class declarations? Assume in each case that the text constitutes the entire contents of a file called Fred.java? A. public class Fred{ public int x = 0; public Fred (int x){ this.x=x; } } B. public class fred{ public int x = 0; public Fred (int x){ this.x=x; } } C. public class Fred extends MyBaseClass, MyOtherBaseClass{ public int x = 0; public Fred(int xval){ x=xval; } } D. protected class Fred{ private int x = 0; private Fred (int xval){ x=xval; } } E. import java.awt.*; public class Fred extends Object{ int x; private Fred(int xval){ x = xval; } }
50. A class design requires that a particular member variable must be accessible for direct access by any subclasses of this class. but otherwise not by classes which are not members of the same package. What should be done to achieve this? A. The variable should be marked public B. The variable should be marked private C. The variable should be marked protected D. The variable should have no special access modifier E. The variable should be marked private and an accessor method provided
51. Which correctly create an array of five empty Strings? A. String a[] = new String[5]; for (int i=0;i<5;a[i++]=””); B. String a []={“”,””,””,””,””}; C. String a[5]; D. String [5] a; E. String [] a = new String[5]; for (int i = 0 ;i<5;a[i++] = null);
52. Which cannot be added to a Container? A. an Applet B. a Component C. a Container D. a MenuComponent E. a panel
53. Which is the return value of Event listener?s method? A. String B. AWTEvent C. void D. int
54. If we implements MouseListener, which is corrected argument of its method? (short answer)
55. Use the operator “>>” and “>>>”. Which statement is true? A. 1010 0000 0000 0000 0000 0000 0000 0000 >> 4 give 0000 1010 0000 0000 0000 0000 0000 0000 B. 1010 0000 0000 0000 0000 0000 0000 0000 >> 4 give 1111 1010 0000 0000 0000 0000 0000 0000 C. 1010 0000 0000 0000 0000 0000 0000 0000 >>> 4 give 0000 1010 0000 0000 0000 0000 0000 0000 D. 1010 0000 0000 0000 0000 0000 0000 0000 >>> 4 give 1111 1010 0000 0000 0000 0000 0000 0000
56. Give following fragment. Outer: for(int i=0; i<3; i++) inner:for(int j=0;j<3;j++){ If(j>1)break outer; System.out.println(j+”and”+i); } Which will be output? A. 0 and 0 B. 0 and 1 C. 0 and 2 D. 0 and 3 E. 1 and 0 F. 1 and 1 G. 1 and 2 H. 1 and 3 I. 2 and 0 J. 2 and 1 K. 2 and 2 L. 2 and 3
57. Examine the following code which includes an inner class: public final class Test4 implements A{ class Inner{ void test(){ if (Test4.this.flag);{ sample(); } } private boolean flag=false; } public void sample(){ System.out.println(“Sample”); } public Test4(){ (new Inner()).test(); } public static void main(String args[]){ new Test4(); } } What is the result: A.Print out “Sample” B.Program produces no output but termiantes correctly. C. Program does not terminate. D.The program will not compile
58. What is written to the standard output given the following statement: System.out.println(47); Select the right answer: A.4 B.5 C.6 D.7 E.0
59. Look the inheritance relation: person
----------------
man woman In a source of java have the following line: person p=new man(); What statement are corrected? A. The expression is illegal. B. Compile corrected but running wrong. C. The expression is legal. D. Will construct a person?s object.
60. Look the inheritance relation: person
----------------
man woman In a source of java have the following line: woman w=new man():
What statement are corrected? A. The expression is illegal. B. Compile corrected but running wrong. C. The expression is legal. D. Will construct a woman object.
61． Which can NOT be used in declaring or declaring and initializing an automatic (method local) variable? A. final B. static C. expressions D. Constants of non-primitive type E. initialized arrays (such as “ {“Hello”,”Good bye”}”).
62． Given the following incomplete method: 1) public void method(){ 2) 3) if (someTestFails()){ 4) 5) } 6) 7) } You want to make this method throw an IOException if,and only if,the method someTestFails() returns a value of true. Which changes achieve this? A. Add at line 2:IOException e; B. Add at line 4:throw e; C. Add at line 4:throw new IOException(); D. Add at line 6:throw new IOException(); E. Modify the method declaration to indicate that an object of type Exception might be thrown.
63． Given the following definition: String s = null; Which code fragments cause an object of type NullPointerException to be thrown? A. if((s!=null)&(s.length()>0)) B. if((s!=null)&&(s.length()>0)) C. if((s==null)(s.length()==0)) D. if((s==null)(s.length()==0))
64． The following is a program 1) class Exsuper{ 2) String name; 3) String nick_name; 4) 5) public ExSuper(String s,String t){ 6) name = s; 7) nick_name = t; 8) } 9) 10) public string toString(){ 11) return name; 12) } 13) } 14) 15) public class Example extends ExSuper{ 16) 17) public Example(String s,String t){ 18) super(s,t); 19) } 20) 21) public String to String(){ 22) return name +”a.k.a”+nick_name; 23) } 24) 25) public static void main(String args[]){ 26) ExSuper a = new ExSuper(“First”,”1st”); 27) ExSuper b = new Example(“Second”,”2nd”); 28) 29) System.out.println(“a is”+a.toString()); 30) System.out.println(“b is”+b.toString()); 31) } 32) } What happens when the user attempts to compile and run this program? ` A. A Compiler error occurs at line 21 B. An object of type ClassCastException is thrown at line 27 C.The following output: a is First b is second D. The following output: a is First b is Secong a.k.a 2nd F. The following output: a is First a.k.a 1st b is Second a.k.a 2nd
65． Which statements are true about Listeners? A. At most one listener can be added to any simple Component. B. The return value from a listener is used to control the invocation of other listener C. If multiple listeners are added to a single component, they must all be made friends to each other D. If multiple listeners are added to single component, the order of invocation of the listener is not specified. E. In the AWT, listener methods generally take an argument, which is an instance of some subclass of java.awt.AWTEvent class.
66． Given the following class outline: class Example{ private int x; // rest of class body public static void main(String args[]){ //implementation of main mehtod} } Which statement is true? A. x=2 is a valid assignment in the main() method of class Example. B. Changing private int x to int x would make x=2 a valid assignment in the main() method of class Example. C. Changing private int x to public int x would make x=2 a valid assignment in the main() method of class Example. D. Changing private int x to static int x would make x=2 a valid assignment in the main() method of class Example. E. Changing class Example to public class Example would make x=2 a valid assignment in the main() method of class Example.
67． Which statement is true about an inner class? A. It must be anonymous B. It can not implement an interface C. It is only accessible in the enclosing class D. It can access any final variables in any enclosing scope.
68． Which statement is true about the grid bag layout manager? A. The number of rows and columns is fixed when the container is created. B. The number of rows and columns is fixed when the GridBagLayout object is created. C. If a component has a fill value of BOTH, then as the container change size, the component is resized. D. Every component must carry a non-zero weightx and weighty value when it is added to the container E. If a row has a weighty value that is non-zero, then as the container changes height, the row changes height.
69． Which statement are true about writing a class that is to handle the events issued by a user interface component. A. Subclassing an adapter is inappropriate in this case. B. The class should implement some listener interface C. A class can implement multiple listener interfaces if desired. D. A subclass of an AWT component cannot listen to its own events. E. When implements listener interface, a class need only provide those handler methods that it chooses.
70．The argument for a class?s main() method is called args, and the class is invoked as follows. java Example cat What would be the effect of trying to access args[0] in the main method? A. The value produced is cat B. The value produced is java C. The value produced is Example D. An object of type NullPointerException is thrown. E. An object of type ArrayIndexOutofBoundsException is thrown.
71． Which best describes the requirements of a fully encapsulated class? A. Mehtods must not be private. B. Variables must not be public. C. The class must be marked final D. Public methods are all marked final. E. Modification of the objects state is only possible using method calls.
72．Which contains objects without ordering, duplication, or any particular lookup/retrieval mechanism? A. Map B. Set C. List D. Collection E. Enumeration
73．What might cause the current thread to stop executing? A. An interrupted exception is thrown. B. The thread execute a sleep() call. C. The thread constructs a new thread D. A thread of higher priority becomes ready E. The thread executes a read() call on InputStream
74．Which statements are true about threads? A. Threads created from the same class all finish together. B. A thread can be created only by subclassing java.lang.Thread. C. Invoking the suspend() method stops a thread so that it cannot be restarted. D. The Java interpreter?s natural exit occurs when no non-daemon threads remain alive. E. Uncoordinated changes to shared data by multiple threads may result in the data being read, or left, in an inconsistent state.
75．What might form part of a correct inner class declaration or combined declaration and instantiation? A. private class C B. new SimpleInterface(){ C. new ComplexInterface(x){ D. private final abstract class( E. new ComplexClass() implements SimpleInterface
76． Which statements are true about the garbage collection mechanisms? A. The garbage collection mechanism release memory at pridictable times. B. A correct program must not depend upon the timing or order of garbage collection C. Garbage collection ensures that a program will NOT run out of memory during execution D. The programmer can indicate that a reference through a local variable is no longer going to be used. E. The programmer has a mechanism that explicitly and immediately frees the memory used by Java objects.
