A.Set extends Collection.
B.All methods defined in Set are also defined in Collection.
C.List extends Collection.
D.All methods defined in List are also defined in Collection.
E.Map extends Collection.
您可能感兴趣的试卷
你可能感兴趣的试题
Which code fragments will succeed in printing the last argument given on the command line to the standard output, and exit gracefully with no output if no arguments are given?()
CODE FRAGMENT a:
public static void main(String args[]) {
if (args.length != 0)
System.out.println(args[args.length-1]);
}
CODE FRAGMENT b:
public static void main(String args[]) {
try { System.out.println(args[args.length]); }
catch (ArrayIndexOutOfBoundsException e) {}
}
CODE FRAGMENT c:
public static void main(String args[]) {
int ix = args.length;
String last = args[ix];
if (ix != 0) System.out.println(last);
}
CODE FRAGMENT d:
public static void main(String args[]) {
int ix = args.length-1;
if (ix > 0) System.out.println(args[ix]);
}
CODE FRAGMENT e:
public static void main(String args[]) {
try { System.out.println(args[args.length-1]);
}catch (NullPointerException e) {}
}
A.Code fragment a.
B.Code fragment b.
C.Code fragment c.
D.Code fragment d.
E.Code fragment e.
A.Objects are deleted when they can no longer be accessed through any reference.
B.The finalize() method will eventually be called on every object.
C.The finalize() method will never be called more than once on an object.
D.An object will not be garbage collected as long as it is possible for an active part of the program to access it through a reference.
E.The garbage collector will use a mark and sweep algorithm.
A.The value of an int is undetermined.
B.The value of all numeric types is zero.
C.The compiler may issue an error if the variable is used before it is initialized.
D.The value of a String variable is "" (empty string).
E.The value of all object variables is null.
Which statements concerning the relationships between the following classes are true?()
class Foo { int num;
Baz comp = new Baz();
}
class Bar { boolean flag;
}
class Baz extends Foo {
Bar thing = new Bar();
double limit;
}
A.A Bar is a Baz.
B.A Foo has a Bar.
C.A Baz is a Foo.
D.A Foo is a Baz.
E.A Baz has a Bar.
A.The operation col1.retainAll(col2) will not modify the col1 object.
B.The operation col1.removeAll(col2) will not modify the col2 object.
C.The operation col1.addAll(col2) will return a new collection object, containing elements from both col1 and col2.
D.The operation col1.containsAll(Col2) will not modify the col1 object.
Which statements concerning the following code are true?()
class a {
public a() {}
public a(int i) { this(); }
}
class b extends a {
public boolean b(String msg) { return false; }
}
class c extends b
{ private c() { super(); }
public c(String msg) { this(); }
public c(int i) {}
}
A.The code will fail to compile.
B.The constructor in a that takes an int as an argument will never be called as a result of constructing an object of class b or c.
C.Class c has three constructors.
D.Objects of class b cannot be constructed.
E.At most one of the constructors of each class is called as a result of constructing an object of class c.
Which expressions will evaluate to true if preceded by the following code?()
String a = "hello";
String b = new String(a);
String c = a;
char[] d = { ’h’, ’e’, ’l’, ’l’, ’o’ };
A.(a == "Hello")
B.(a == b)
C.(a == c)
D.a.equals(b)
E.a.equals(d)
What will be the result of attempting to run the following program?()
public class Qaa75 {
public static void main(String args[]) {
String[][][] arr = {
{ {}, null },
{ { "1", "2" }, { "1", null, "3" } },
{},
{ { "1", null } } };
System.out.println(arr.length + arr[1][2].length);
}
}
A.The program will terminate with an ArrayIndexOutOfBoundsException.
B.The program will terminate with a NullPointerException.
C.4 will be written to standard output.
D.6 will be written to standard output.
E.7 will be written to standard output.
Which code fragments will succeed in initializing a two-dimensional array named tab with a size that will cause the expression tab[3][2] to access a valid element?()
CODE FRAGMENT a: int[][] tab = { { 0, 0, 0 }, { 0, 0, 0 } };
CODE FRAGMENT b: int tab[][] = new int[4][]; for (int i=0; i
CODE FRAGMENT c: int tab[][] = { 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0 };
CODE FRAGMENT d: int tab[3][2];
CODE FRAGMENT e: int[] tab[] = { {0, 0, 0}, {0, 0, 0}, {0, 0, 0}, {0, 0, 0} };
A.Code fragment a.
B.Code fragment b.
C.Code fragment c.
D.Code fragment d.
E.Code fragment e.
A.Mark the method with the keyword public.
B.Mark the method with the keyword protected.
C.Mark the method with the keyword private.
D.Mark the method with the keyword package.
E.Do not mark the method with any accessibility modifiers.
最新试题
Which statement is true?()
A programmer must create a generic class MinMax and the type parameter of MinMax must implement Comparable. Which implementation of MinMax will compile?()
Given a class whose instances, when found in a collection of objects, are sorted by using the compareTo() method, which two statements are true?()
What is the result?()
What is the result?()
Which statement is true?()
Which two statements are true?()
A programmer iterates over the TreeSet and prints the name of each Drink object. What is the result?()
Which three will compile and run without exception?()
Which statement is true?()