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.()
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问题:单选题Float pi = new Float(3.14f); if(pi>3) { System.out.print(”pi is bigger than 3. “); } else { System.out.print(”pi is not bigger than 3. “); } finally { System.out.println(”Have a nice day.”); } What is the result?()ACompilation fails.Bpi is bigger than 3.CAn exception occurs at runtime.Dpi is bigger than 3. Have a nice day.Epi is not bigger than 3. Have a nice day.
问题:单选题11. rbo = new ReallyBigObject(); 12. // more code here 13. rbo = null; 14. /* insert code here */ Which statement should be placed at line 14 to suggest that the virtual machine expend effort toward recycling the memory used by the object rbo?()ASystem.gc();BRuntime.gc();CSystem.freeMemory();DRuntime.getRuntime().growHeap();ERuntime.getRuntime().freeMemory();
问题:单选题11. class Converter { 12. public static void main(String[] args) { 13. Integer i = args[0]; 14. int j = 12; 15. System.out.println(”It is “ + (j==i) + “that j==i.”); 16. } 17. } What is the result when the programmer attempts to compile the code and run it with the command java Converter 12?()AIt is true that j==i.BIt is false that j==i.CAn exception is thrown at runtime.DCompilation fails because of an error in line 13.
问题:填空题1. public class test { 2. public static string output = “” 3. 4. public static void foo(int i) { 5. try { 6. if(i= =1) { 7. throw new Exception (); 8. } 9. output += “1”; 10.} 11. catch(Exception e) { 12. output += “2”; 13. return; 14.} 15. finally ( 16. output += “3”; 17. ) 18. output += “4”; 19. } 20. 21. public static void main (string args[]) ( 22. foo(0); 23. foo(1); 24. 25. ) 26. } What is the value of the variable output at line 24?()
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 of the following statements are true?()AThe equals() method determines if reference values refer to the same object.BThe == operator determines if the contents and type of two separate objects match.CThe equals() method returns true only when the contents of two objects match.DThe class File overrides equals() to return true if the contents and type of two separate objects match.
问题:单选题import java.util.*; public class WrappedString { private String s; public WrappedString(String s) { this.s = s; } public static void main(String[] args) { HashSet hs = new HashSet(); WrappedString ws1 = new WrappedString(”aardvark”); WrappedString ws2 = new WrappedString(”aardvark”); String s1 = new String(”aardvark”); String s2 = new String(”aardvark”); hs.add(ws1); hs.add(ws2); hs.add(s1); hs.add(s2); System.out.println(hs.size()); } } What is the result?()A0B1C2D3E4FCompilation fails.GAn exception is thrown at runtime.
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.
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 X implements Runnable ( private int x; private int y; public static void main(String [] args) ( X that = new X(); (new Thread(that)) . start( ); (new Thread(that)) . start( ); ) public synchronized void run( ) ( for (;;) ( x++; y++; System.out.printIn(“x = “ + x + “, y = “ + y); ) ) ) What is the result?()AAn error at line 11 causes compilation to fail.BErrors at lines 7 and 8 cause compilation to fail.CThe 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”)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 twice (for example, “x=1, y=1” followed by “x=1, y=1”)EThe 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=2s, y=2”)
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:填空题Public class test ( Public static void main (String args[]) ( System.out.printIn (6 ^ 3); ) ) What is the output?()
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.
问题:单选题1. interface A { public void aMethod(); } 2. interface B { public void bMethod(); } 3. interface C extends A,B { public void cMethod(); } 4. class D implements B { 5. public void bMethod() { } 6. } 7. class E extends D implements C { 8. public void aMethod() { } 9. public void bMethod() { } 10. public void cMethod() { } 11. } What is the result?()ACompilation fails because of an error in line 3.BCompilation fails because of an error in line 7.CCompilation fails because of an error in line 9.DIf you define D e = new E(), then e.bMethod() invokes the version of bMethod()defined in Line 5.EIf you define D e = (D)(new E()),then e.bMethod() invokes the version of bMethod() defined in Line 5.FIf you define D e = (D)(new E()), then e.bMethod() invokes the version of bMethod() defined in Line 9.
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:多选题Which of these are keywords in Java?()AdefaultBNULLCStringDthrowsElong
问题:单选题int x= 10; do { x--; } while(x< 10); How many times will line 37 be executed?()Aten timesBzero timesCone to me timesDmore than ten times