This is my mock Exam No 2 based on the Objectives for the Sun Java
Programmers Exam. Please email me if you have any corrections or comments.
You should assume that the real thing will be harder. This one is probably easier than my Exam No 1
What will happen when you attempt to compile and run this code?
abstract class Base{
abstract public void myfunc();
public void another(){
System.out.println("Another method");
}
}
public class Abs extends Base{
public static void main(String argv[]){
Abs a = new Abs();
a.amethod();
}
public void myfunc(){
System.out.println("My func");
}
public void amethod(){
myfunc();
}
}
1) The code will compile and run, printing out the words "My Func"
2) The
compiler will complain that the Base class has non abstract methods
3) The
code will compile but complain at run time that the Base class has non abstract
methods
4) The compiler will complain that the method myfunc in the base
class has no body, nobody at all to looove it
public class MyMain{
public static void main(String argv){
System.out.println("Hello cruel world");
}
}
1) The compiler will complain that main is a reserved word and cannot be used
for a class
2) The code will compile and when run will print out "Hello cruel
world"
3) The code will compile but will complain at run time that no
constructor is defined
4) The code will compile but will complain at run time
that main is not correctly defined
Which of the following are Java
modifiers?
1)public
2) private
3) friendly
4)
transient
4) vagrant
What will happen when you attempt to compile and run this code?
class Base{
abstract public void myfunc();
public void another(){
System.out.println("Another method");
}
}
public class Abs extends Base{
public static void main(String argv[]){
Abs a = new Abs();
a.amethod();
}
public void myfunc(){
System.out.println("My func");
}
public void amethod(){
myfunc();
}
}
1) The code will compile and run, printing out the words "My Func"
2) The
compiler will complain that the Base class is not declared as abstract.
3)
The code will compile but complain at run time that the Base class has non
abstract methods
4) The compiler will complain that the method myfunc in the
base class has no body, nobody at all to looove it
Why might you define a method as native?
1) To get to access hardware that Java does not know about
2) To define a
new data type such as an unsigned integer
3) To write optimised code for
performance in a language such as C/C++
4) To overcome the limitation of the
private scope of a method
What will happen when you attempt to compile and run this code?
class Base{
public final void amethod(){
System.out.println("amethod");
}
}
public class Fin extends Base{
public static void main(String argv[]){
Base b = new Base();
b.amethod();
}
}
1) Compile time error indicating that a class with any final methods must be
declared final itself
2) Compile time error indicating that you cannot
inherit from a class with final methods
3) Run time error indicating that
Base is not defined as final
4) Success in compilation and output of
"amethod" at run time.
What will happen when you attempt to compile and run this code?
public class Mod{
public static void main(String argv[]){
}
public static native void amethod();
}
1) Error at compilation: native method cannot be static
2) Error at
compilation native method must return value
3) Compilation but error at run
time unless you have made code containing native amethod available
4)
Compilation and execution without error
What will happen when you attempt to compile and run this code?
private class Base{}
public class Vis{
transient int iVal;
public static void main(String elephant[]){
}
}
1)Compile time error: Base cannot be private
2)Compile time error
indicating that an integer cannot be transient
3)Compile time error transient
not a data type
4)Compile time error malformed main method
//File P1.java
package MyPackage;
class P1{
void afancymethod(){
System.out.println("What a fancy method");
}
}
//File P2.java
public class P2 extends P1{
afancymethod();
}
1) Both compile and P2 outputs "What a fancy method" when run
2) Neither
will compile
3) Both compile but P2 has an error at run time
4) P1
compiles cleanly but P2 has an error at compile time
You want to find out the value of the last element of an array. You write the following code. What will happen when you compile and run it.?
public class MyAr{
public static void main(String argv[]){
int[] i = new int[5];
System.out.println(i[5]);
}
}
1) An error at compile time
2) An error at run time
3) The value 0 will
be output
4) The string "null" will be output
You want to loop through an array and stop when you come to
the last element. Being a good java programmer and forgetting everything you
ever knew about C/C++ you know that arrays contain information about their size.
Which of the following can you
use?
1)myarray.length();
2)myarray.length;
3)myarray.size
4)myarray.size();
What best describes the appearance of an applet with the following code?
import java.awt.*;
public class FlowAp extends Frame{
public static void main(String argv[]){
FlowAp fa=new FlowAp();
fa.setSize(400,300);
fa.setVisible(true);
}
FlowAp(){
add(new Button("One"));
add(new Button("Two"));
add(new Button("Three"));
add(new Button("Four"));
}//End of constructor
}//End of Application
1) A Frame with buttons marked One to Four placed on each edge.
2) A Frame
with buutons marked One to four running from the top to bottom
3) A Frame
with one large button marked Four in the Centre
4) An Error at run time
indicating you have not set a LayoutManager
How do you indicate where a component will be positioned using Flowlayout?
1) North, South,East,West
2) Assign a row/column grid reference
3) Pass
a X/Y percentage parameter to the add method
4) Do nothing, the FlowLayout
will position the component
How do you change the current layout manager for a container
1) Use the setLayout method
2) Once created you cannot change the current
layout manager of a component
3) Use the setLayoutManager method
4) Use
the updateLayout method
Which of the following are fields of the GridBagConstraints class?
1) ipadx
2) fill
3) insets
4) width
What most closely matches the appearance when this code runs?
import java.awt.*;
public class CompLay extends Frame{
public static void main(String argv[]){
CompLay cl = new CompLay();
}
CompLay(){
Panel p = new Panel();
p.setBackground(Color.pink);
p.add(new Button("One"));
p.add(new Button("Two"));
p.add(new Button("Three"));
add("South",p);
setLayout(new FlowLayout());
setSize(300,300);
setVisible(true);
}
}
1) The buttons will run from left to right along the bottom of the
Frame
2) The buttons will run from left to right along the top of the
frame
3) The buttons will not be displayed
4) Only button three will show
occupying all of the frame
Which statements are correct about the anchor field?
1) It is a field of the GridBagLayout manager for controlling component
placement
2) It is a field of the GridBagConstraints class for controlling
component placement
3) A valid setting for the anchor field is
GridBagConstraints.NORTH
4) The anchor field controls the height of
components added to a container
What will happen when you attempt to compile and run the following code?
public class Bground extends Thread{
public static void main(String argv[]){
Bground b = new Bground();
b.run();
}
public void start(){
for (int i = 0; i <10; i++){
System.out.println("Value of i = " + i);
}
}
}
1) A compile time error indicating that no run method is defined for the
Thread class
2) A run time error indicating that no run method is defined for
the Thread class
3) Clean compile and at run time the values 0 to 9 are
printed out
4) Clean compile but no output at runtime
When using the GridBagLayout manager, each new component requires a new instance of the GridBagConstraints class. Is this statement
1) true
2) false
Which most closely matches a description of a Java Map?
1) A vector of arrays for a 2D geographic representation
2) A class for
containing unique array elements
3) A class for containing unique vector
elements
4) An interface that ensures that implementing classes cannot
contain duplicates
How does the set collection deal with duplicate elements?
1) An exception is thrown if you attempt to add an element with a duplicate
value
2) The add method returns false if you attempt to add an element
with a duplicate value
3) A set may contain elements that return duplicate
values from a call to the equals method
4) Duplicate values will cause an
error at compile time
What can cause a thread to stop executing?
1) The program exits via a call to exit(0);
2) The priority of another
thread is increased
3) A call to the stop method of the Thread class
4) A
call to the halt method of the Thread class
For a class defined insid