单项选择题

11. public static void main(String[] args) { 
12. Object obj =new int[] { 1,2,3 }; 
13. int[] someArray = (int[])obj; 
14. for (int i: someArray) System.out.print(i +“ “) 
15. } 
What is the result? ()

A. 1 2 3
B. Compilation fails because of an error in line 12.
C. Compilation fails because of an error in line 13.
D. Compilation fails because of an error in line 14.
E. A ClassCastException is thrown at runtime.


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2.单项选择题

public class Ball { 
public enum Color { RED, GREEN, BLUE }; 
public void foo() { 
// insert code here 
{ System.out.println(c); } 
} 
} 
Which code inserted at line 14 causes the foo method to print RED, GREEN, and BLUE?() 

A. for( Color c : Color.values())
B. for( Color c = RED; c <= BLUE; c++)
C. for( Color c; c.hasNext() ; c.next())
D. for( Color c = Color[0]; c <= Color[2]; c++)
E. for( Color c = Color.RED; c <= Color.BLUE; c++)

3.多项选择题Which two code fragments correctly create and initialize a static array of int elements?() 

A. static final int[] a = { 100,200 };
B. static final int[] a; static { a=new int[2]; a[0]=100; a[1]=200; }
C. static final int[] a = new int[2] { 100,200 };
D. static final int[] a; static void init() { a = new int[3]; a[0]=100; a[1]=200; }

4.多项选择题

35. String #name = “Jane Doe”; 
36. int$age=24; 
37. Double_height = 123.5; 
38. double~temp = 37.5; 
Which two are true?()

A. Line 35 will not compile.
B. Line 36 will not compile.
C. Line 37 will not compile.
D. Line 38 will not compile.

5.单项选择题

55. int []x= {1, 2,3,4, 5}; 
56. int y[] =x; 
57. System.out.println(y[2]); 
Which is true?() 

A. Line 57 will print the value 2.
B. Line 57 will print the value 3.
C. Compilation will fail because of an error in line 55.
D. Compilation will fail because of an error in line 56.

9.多项选择题

public abstract class Shape { 
private int x; 
private int y; 
public abstract void draw(); 
public void setAnchor(int x, int y) { 
this.x = x; 
this.y = y; 
} 
} 
Which two classes use the Shape class correctly?()

A. public class Circle implements Shape { private int radius; }
B. public abstract class Circle extends Shape { private int radius; }
C. public class Circle extends Shape { private int radius; public void draw(); }
D. public abstract class Circle implements Shape { private int radius; public void draw(); }
E. public class Circle extends Shape { private int radius;public void draw() {/* code here */} }
F. public abstract class Circle implements Shape { private int radius;public void draw() { / code here */ } }

10.单项选择题

interface Data { public void load(); } 
abstract class Info { public abstract void load(); } 
Which class correctly uses the Data interface and Info class?() 

A. public class Employee extends Info implements Data { public void load() { /*do something*/ } }
B. public class Employee implements Info extends Data { public void load() { /*do something*/ } }
C. public class Employee extends Info implements Data { public void load() { /*do something */ } public void Info.load() { /*do something*/ } }
D. public class Employee implements Info extends Data { public void Data.load() { /*dsomething */ } public void load() { /*do something */ } }
E. public class Employee implements Info extends Data { public void load() { /*do something */ } public void Info.load(){ /*do something*/ } }
F. public class Employee extends Info implements Data{ public void Data.load() { /*do something*/ } public void Info.load() { /*do something*/ } }