问题:单选题int i = 0; while (true) { if(i==4) { break; } ++i; } System.out.println(“i=”+i); What is the result?()Ai = 0Bi = 3Ci = 4Di = 5ECompilation fails.
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问题:单选题Which statements, when inserted at the indicated position in the following code, will cause a runtime exception when attempting to run the program?() class A {} class B extends A {} class C extends A {} public class Q3ae4 { public static void main(String args[]) { A x = new A(); B y = new B(); C z = new C(); // insert statement here } }A x = y;B z = x;C y = (B) x;D z = (C) y;E y = (A) y;
问题:单选题Which gets the name of the parent directory file “file.txt”?()AString name= File.getParentName(“file.txt”);BString name= (new File(“file.txt”)).getParent();CString name = (new File(“file.txt”)).getParentName();DString name= (new File(“file.txt”)).getParentFile();EDirectory dir=(new File (“file.txt”)).getParentDir(); String name= dir.getName();
问题:单选题What will be the result of attempting to compile and run the following code?() public class Q6b0c { public static void main(String args[]) { int i = 4; float f = 4.3; double d = 1.8; int c = 0; if (i == f) c++; if (((int) (f + d)) == ((int) f + (int) d)) c += 2; System.out.println(c); } }A The code will fail to compile.B 0 will be written to the standard output.C 1 will be written to the standard output.D 2 will be written to the standard output.E 3 will be written to the standard output.
问题:单选题10. class Nav{ 11. public enum Direction { NORTH, SOUTH, EAST, WEST } 12. } 13. public class Sprite{ 14. // insert code here 15. } Which code, inserted at line 14, allows the Sprite class to compile?()ADirection d = NORTH;BNav.Direction d = NORTH;CDirection d = Direction.NORTH;DNav.Direction d = Nav.Direction.NORTH;
问题:多选题public void test() { try { oneMethod(); System.out.println("condition 1"); } catch (ArrayIndexOutOfBoundsException e) { System.out.println("condition 2"); } catch(Exception e) { System.out.println("condition 3"); } finally { System.out.println("finally"); } } Which will display if oneMethod run normally?()Acondition 1Bcondition 2Ccondition 3Dfinally
问题:多选题11. public interface Status { 12. /* insert code here */ int MY_VALUE = 10; 13. } Which three are valid on line 12?()AfinalBstaticCnativeDpublicEprivateFabstractGprotected
问题:单选题public class Test { public static void leftshift(int i, int j) { i<<=j; } public static void main(String args) { int i = 4, j = 2; leftshift(i, j); System.out.printIn(i); } } What is the result? ()A2B4C8D16EThe code will not compile.
问题: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?()AJust after line 5.BJust after line 6.CJust after line 7.DJust after line 8(that is, as the method returns).
问题:单选题public class X implements Runnable( private int x; private int y; public static void main(Stringargs) X that = new X(); (new Thread(that)).start(); (new Thread(that)).start(); ) public void run() ( for (;;) ( x++; y++; System.out.printIn(“x=” + x + “, y = ” + y); ) ) What is the result?()AErrors at lines 7 and 8 cause compilation to fail.BThe program prints pairs of values for x and y that might not always be the same on the same line (for example, “x=2, y=1”).CThe program prints pairs of values for x and y that are always the same on the same line (for example, “x=1, y=1”. In addition, each value appears twice (for example, “x=1, y=1” followed by “x=1, y=1”).DThe program prints pairs of values for x and y that are always the same on the same line (for example, “x=1, y=1”. In addition, each value appears only for once (for example, “x=1, y=1” followed by “x=2, y=2”).
问题:多选题Which are syntactically valid statement at// point x?() class Person { private int a; public int change(int m){ return m; } } public class Teacher extends Person { public int b; public static void main(String arg[]){ Person p = new Person(); Teacher t = new Teacher(); int i; // point x } }Ai = m;Bi = b;Ci = p.a;Di = p.change(30);Ei = t.b.
问题:单选题public class X { public static void main(String [] args) { try { badMethod(); System.out.print(“A”); } catch (RuntimeException ex) { System.out.print(“B”); } catch (Exception ex1) { System.out.print(“C”); } finally { System.out.print(“D”); } System.out.print(“E”); } public static void badMethod() { throw new RuntimeException(); } } What is the result?()ABDBBCDCBDEDBCDEEABCDEFCompilation fails.
问题:单选题public class Drink implements Comparable { public String name; public int compareTo(Object o) { return 0; } } and: Drink one = new Drink(); Drink two = new Drink(); one.name= “Coffee”; two.name= “Tea”; TreeSet set = new TreeSet(); set.add(one); set.add(two); A programmer iterates over the TreeSet and prints the name of each Drink object. What is the result?()ATeaBCoffeeCCoffee TeaDCompilation fails.EThe code runs with no output.FAn exception is thrown at runtime.
问题:单选题public class Foo { public static void main (String []args) { int i = 1; int j = i++; if ((i>++j) && (i++ ==j)) { i +=j; } } } What is the final value of i?()A1B2C3D4E5
问题:多选题Which of these are keywords in Java?()AdefaultBNULLCStringDthrowsElong
问题:多选题ArraryList a = new ArrayList(); a.add(“Alpha”); a.add(“Bravo”): a.add(“Charlie”); a.add(“Delta”); Iterator iter = a.iterator(); Which two, added at line 17, print the names in the ArrayList in alphabetical order?()Afor (int i=0; i< a.size(); i++) System.out.println(a.get(i)));Bfor (int i=0; i< a.size(); i++) System.out.println(a[i]);Cwhile( iter.hasNext() ) System.out.println(iter.next()) ;Dfor (int i=0, i< a.size(); i++) System.out.println(iter[i]);Efor (int i=0; i< a.size(); i++) System.out.println(iter.get(i));
问题:填空题3. string foo = “ABCDE”; 4. foo.substring(3); 5. foo.concat(“XYZ”); 6. Type the value of foo at line 6.()
问题:多选题Which statements concerning the event model of the AWT are true?()AAt most one listener of each type can be registered with a component.BMouse motion listeners can be registered on a List instance.CThere exists a class named ContainerEvent in package java.awt.event.DThere exists a class named MouseMotionEvent in package java.awt.event.EThere exists a class named ActionAdapter in package java.awt.event.
问题:单选题11. public class Test { 12. public void foo() { 13. assert false; 14. assert false; 15. } 16. public void bar(){ 17. while(true){ 18. assert false; 19. } 20. assert false; 21. } 22. } What causes compilation to fail?()ALine 13BLine 14CLine 18DLine 20
问题:单选题1. public class ForBar { 2. public static void main(String []args) { 3. int i = 0, j = 5; 4. tp: for (;;) { 5. i ++; 6. for(;;) 7. if(i > --j) break tp; 8. } 9. system.out.printIn(“i = ” + i + “, j = “+ j); 10. } 11. } What is the result?()AThe program runs and prints “i=1, j=0”BThe program runs and prints “i=1, j=4”CThe program runs and prints “i=3, j=4”DThe program runs and prints “i=3, j=0”EAn error at line 4 causes compilation to fail.FAn error at line 7 causes compilation to fail.