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Java Programmer Certification Mock Exam No 2

60 Questions


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


Questions

Question 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

Answer to Question 1



Question 2)

What will happen when you attempt to compile and run this code?

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

Answer to Question 2


Question 3)

Which of the following are Java modifiers?

1)public
2) private
3) friendly
4) transient
4) vagrant

Answer to Question 3


Question 4)

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

Answer to Question 4



Question 5)

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

Answer to Question 5



Question 6)

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.

Answer to Question 6


Question 7)

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

Answer to Question 7



Question 8)

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

Answer to Question 8




Question 9)

What happens when you attempt to compile and run these two files in the same directory?

//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

Answer to Question 9


Question 10)

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

Answer to Question 10


Question 11)

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();

Answer to Question 11


Question 12)

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

Answer to Question 12


Question 13)

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

Answer to Question 13)



Question 14)

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

Answer to Question 14)


Question 15)

Which of the following are fields of the GridBagConstraints class?

1) ipadx
2) fill
3) insets
4) width

Answer to Question 15)


Question 16)

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

Answer to Question 16)


Question 17)

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

Answer to Question 17)


Question 18)

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

Answer to Question 18)


Question 19)

When using the GridBagLayout manager, each new component requires a new instance of the GridBagConstraints class. Is this statement

1) true
2) false

Answer to Question 19)


Question 20)

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

Answer to Question 20)


Question 21)

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

Answer to Question 21)


Question 22)

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


Answer to Question 22)


Question 23)

For a class defined insid