SCJP程序员认证考试 题目列表
多选题public class SyncTest{ public static void main（String args） { final StringBuffer s1= new StringBuffer（）； final StringBuffer s2= new StringBuffer（）； new Thread （） { public void run（） { synchronized（s1） { s2.append（“A”）； synchronized（s2） { s2.append（“B”）； System.out.print（s1）； System.out.print（s2）； } } } }.start（）； new Thread（） { public void run（） { synchronized（s2） { s2.append（“C”）； synchronized（s1） { s1.append（“D”）； System.out.print（s2）； System.out.print（s1）； } } } }.start（）； } } Which two statements are true？ （）AThe program prints “ABBCAD”BThe program prints “CDDACB”CThe program prints “ADCBADBC”DThe output is a non-deterministic point because of a possible deadlock condition.EThe output is dependent on the threading model of the system the program is running on.
单选题public class Test { private static int[] x； public static void main（String[] args） { System.out.println（x[0]）； } } What is the result？（）A 0B nullC Compilation fails.D A NullPointerException is thrown at runtime.E An ArrayIndexOutOfBoundsException is thrown at runtime.
单选题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？（）A The code runs with no output.B An exception is thrown at runtime.C Compilation fails because of an error in line 20.D Compilation fails because of an error in line 21.E Compilation fails because of an error in line 23.F Compilation fails because of an error in line 25.
单选题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？（）A Compilation fails.B An exception is thrown at runtime.C The code executes normally and prints “bar”.D The code executes normally， but nothing prints.
单选题Which of the following range of short is correct？（）A -27 -- 27-1B 0 -- 216-1C -215 -- 215-1D -231 -- 231-1
单选题Which method is an appropriate way to determine the cosine of 42 degrees？（）A Double d = Math.cos（42）；B Double d = Math.cosine（42）；C Double d = Math.cos（Math.toRadians（42））；D Double d = Math.cos（Math.toDegrees（42））；E Double d = Math.cosine（Math.toRadians（42））；
单选题How can you create a listener class that receives events when the mouse is moved？（）A By extending MouseListener.B By implementing MouseListener.C By extending MouseMotionListener.D By implementing MouseMotionListener.E Either by extending MouseMotionListener or extending MouseListener.F Either by implementing MouseMotion Listener or implementing MouseListener.
单选题public class Foo { public void main（ String[] args ） { System.out.println（ “Hello” + args[0] ）； } } What is the result if this code is executed with the command line？（）A HelloB Hello FooC Hello worldD Compilation fails.E The code does not run.
多选题class A { } class Alpha { private A myA = new A（）； void dolt（ A a ） { a = null； } void tryIt（） { dolt（ myA ）； } } Which two statements are correct？（）AThere are no instanced of A that will become eligible for garbage collection.BExplicitly setting myA to null marks that instance to be eligible for garbage collection.CAny call on tryIt（） causes the private instance of A to be marked for garbage collection.DPrivate instances of A become eligible for garbage collection when instances of Alpha become eligible for garbage collection.
单选题What will be written to the standard output when the following program is run？（） public class Q63e3 { public static void main（String args[]） { System.out.println（9 ^ 2）； } }A81B7C11D0Efalse
多选题Which of the following statements are legal？（）Along l = 4990；Bint i = 4L；Cfloat f = 1.1；Ddouble d = 34.4；Edouble t = 0.9F；
单选题11. public enum Title { 12. MR（”Mr.”）， MRS（”Mrs.”）， MS（”Ms.”）； 13. private final String title； 14. private Title（String t） { title = t； } 15. public String format（String last， String first） { 16. return title + “ “ + first + “ “ + last； 17. } 18. } 19. public static void main（String[] args） { 20. System.out.println（Title.MR.format（”Doe”， “John”））； 21. } What is the result？（）A Mr. John DoeB An exception is thrown at runtime.C Compilation fails because of an error in line 12.D Compilation fails because of an error in line 15.E Compilation fails because of an error in line 20.
单选题Which statement is true for the class java.util.ArrayList？（）A The elements in the collection are ordered.B The collection is guaranteed to be immutable.C The elements in the collection are guaranteed to be unique.D The elements in the collection are accessed using a unique key.E The elements in the collections are guaranteed to be synchronized.
单选题public class X { public static void main （Stringargs） { string s = new string （“Hello”）； modify（s）； System.out.printIn（s）； } public static void modify （String s） { s += “world!”； } } What is the result？（）AThe program runs and prints “Hello”BAn error causes compilation to fail.CThe program runs and prints “Hello world!”DThe program runs but aborts with an exception.
多选题Which two statements are reserved words in Java？（）ARunBImportCDefaultDImplement