Java Programmer Certification Mock Exam No 1

Total 60 Questions (Answers to the Certification Questions)

This is a mock Exam based on the Objectives for the Sun Java Programmers Exam.

Because the Objectives for the Java2 exam are very similar to the Objectives for the 1.1 exam, this test is appropriate for studying for the new exam. Questions from 45 onward may include objectives from Java2 exam.

Each question may have one or more correct answers.

Questions


Question 1)

Which of the following lines will compile without warning or error.

1) float f=1.3;
2) char c="a";
3) byte b=257;
4) boolean b=null;
5) int i=10;
 


Question 2)

What will happen if you try to compile and run the following code
public class MyClass { 
        public static void main(String arguments[]) { 
                amethod(arguments); 
                } 
        public void amethod(String[] arguments) { 
                System.out.println(arguments); 
                System.out.println(arguments[1]); 
        } 
}
1) error Can't make static reference to void amethod.
2) error method main not correct
3) error array must include parameter
4) amethod must be declared with String
 


Question 3)

Which of the following will compile without error

1)

import java.awt.*; 
package Mypackage; 
class Myclass {}
2)
package MyPackage; 
import java.awt.*; 
class MyClass{}
3)
/*This is a comment */ 

package MyPackage; 

import java.awt.*; 

class MyClass{}



Question 4)

A byte can be of what size

1) -128 to 127
2) (-2 power 8 )-1 to 2 power 8
3) -255 to 256
4)depends on the particular implementation of the Java Virtual machine


Question 5)

What will be printed out if this code is run with the following command line?
java myprog good morning
public class myprog{ 

public static void main(String argv[])
{ 

System.out.println(argv[2]) 

}
}
1) myprog
2) good
3) morning
4) Exception raised: "java.lang.ArrayIndexOutOfBoundsException: 2"
 


Question 6)


Which of the following are java reserved words?

1) if
2) then
3) goto
4) while
5) case
 


Question 7)


Which of the following are legal identifiers

1) 2variable
2) variable2
3) _whatavariable
4) _3_
5) $anothervar
6) #myvar
 


Question 8)

What will happen when you compile and run the following code?
 
 
public class MyClass{ 

        static int i; 

        public static void main(String argv[]){ 

                System.out.println(i); 

                } 

}
1) Error Variable i may not have been initialized
2) null
3) 1
4) 0
 


Question 9)

What will happen if you try to compile and run the following code?
public class Q { 

        public static void main(String argv[]){ 

                int anar[]=new int[]{1,2,3};

                System.out.println(anar[1]); 

                } 

}
1) 1
2) Error anar is referenced before it is initialized
3) 2
4) Error: size of array must be defined
 
 


Question 10)


What will happen if you try to compile and run the following code?

public class Q { 

        public static void main(String argv[]){ 

                int anar[]=new int[5];

                System.out.println(anar[0]); 

                } 

}
1) Error: anar is referenced before it is initialized
2) null
3) 0
4) 5
 


Question 11)


What will be the result of attempting to compile and run the following code?

abstract class MineBase { 

        abstract void amethod(); 

        static int i; 

}
public class Mine extends MineBase      { 

        public static void main(String argv[]){ 

                        int[] ar=new int[5]; 

                        for(i=0;i < ar.length;i++) 

                                System.out.println(ar[i]); 

                        } 

}
1) a sequence of 5 0's will be printed
2) Error: ar is used before it is initialized
3) Error Mine must be declared abstract
4) IndexOutOfBoundes Error
 


Question 12)

What will be printed out if you attempt to compile and run the following code ?
int i=1; 

        switch (i) { 

                case 0: 

                System.out.println("zero"); 

        break; 

        case 1: 

                System.out.println("one"); 

        case 2: 

                System.out.println("two"); 

        default: 

                System.out.println("default"); 

        }
1) one
2) one, default
3) one, two, default
4) default
 


Question 13)

What will be printed out if you attempt to compile and run the following code?
int i=9; 

switch (i) { 

        default: 

        System.out.println("default"); 

                case 0: 

        System.out.println("zero"); 

                break; 

        case 1: 

                System.out.println("one"); 

        case 2: 

        System.out.println("two"); 

}
1) default
2) default, zero
3) error default clause not defined
4) no output displayed
 


Question 14)

Which of the following lines of code will compile without error

1)

int i=0; 

if(i) { 

        System.out.println("Hello"); 

        }
2)
boolean b=true; 

boolean b2=true; 

if(b==b2) { 

        System.out.println("So true"); 

        }
3)
int i=1; 

int j=2; 

if(i==1|| j==2) 

        System.out.println("OK");
4)
int i=1; 

int j=2; 

if(i==1 &| j==2) 

        System.out.println("OK");



Question 15)

What will be output if you try to compile and run the following code, but there is
no file called Hello.txt in the current directory?.
import java.io.*; 

public class Mine { 

        public static void main(String argv[]){
        Mine m=new Mine(); 

        System.out.println(m.amethod()); 

} 

public int amethod() { 

        try {

                FileInputStream dis=new FileInputStream("Hello.txt"); 

                }catch (FileNotFoundException fne) { 

                        System.out.println("No such file found"); 

                        return -1; 

                        }catch(IOException ioe) { 

                        } finally{ 

        System.out.println("Doing finally"); 

        } 

        return 0; 

        } 

}
1) No such file found
2 No such file found ,-1
3) No such file found, Doing finally, -1
4) 0
 


Question 16)

What tags are mandatory when creating HTML to display an applet

1) name, height, width
2) code, name
3) codebase, height, width
4) code, height, width
 


Question 17)

What will happen if you attempt to compile and run the following code?

1) Compile and run without error
2) Compile time Exception
3) Runtime Exception
 

class Base {} 

class Sub extends Base {} 

class Sub2 extends Base {}
public class CEx{
        public static void main(String argv[]){

                Base b=new Base();

                Sub s=(Sub) b;

                }
}



Question 18)

If the following HTML code is used to display the applet in the code MgAp what will
be displayed at the console?
 

1) Error: no such parameter
2) 0
3) null
4) 30

<applet name=MgAp code=MgAp.class height=400 width=400 parameter HowOld=30 >
</applet>

import java.applet.*; 

import java.awt.*; 

public class MgAp extends Applet{

        public void init(){ 

                System.out.println(getParameter("age")); 

                } 

}
 

 
 
 
 
 
 
 
 
 
 
 


Question 19)

You are browsing the Java HTML documentation for information on the
java.awt.TextField component. You want to create Listener code to respond to focus
events. The only Listener method listed is addActionListener. How do you go about
finding out about Listener methods?

1) Define your own Listener interface according to the event to be tracked
2) Use the search facility in the HTML documentation for the listener needed
3) Move up the hierarchy in the HTML documentation to locate methods in base
classes
4) Subclass awt.event with the appropriate Listener method
 


Question 20)


What will be displayed when you attempt to compile and run the following code

//Code start 

import java.awt.*;
public class Butt extends Frame{
public static void main(String argv[]){ 

        Butt MyBut=new Butt(); 

        }
Butt(){ 

        Button HelloBut=new Button("Hello"); 

        Button ByeBut=new Button("Bye"); 

        add(HelloBut); 

        add(ByeBut); 

        setSize(300,300); 

        setVisible(true); 

        } 

} 

//Code end
1) Two buttons side by side occupying all of the frame, Hello on the left and Bye on
the right
2) One button occupying the entire frame saying Hello
3) One button occupying the entire frame saying Bye
4) Two buttons at the top of the frame one saying Hello the other saying Bye
 


Question 21)


What will be output by the following code?

public class MyFor{

public static void main(String argv[]){ 

    int i; 

    int j; 

    outer: 

    for (i=1;i <3;i++) 

        inner: 

         for(j=1; j<3; j++) { 

                    if (j==2) 

                    continue outer; 

                    System.out.println("Value for i=" + i + " Value for j=" +j); 

                    } 

        } 

}

1) Value for i=1 value for j=1
2) value for i=2 value for j=1
3) value for i=2 value for j=2
4 value for i=3 value for j=1


Question 22)


If g is a graphics instance what will the following code draw on the screen?.
 

g.fillArc(45,90,50,50,90,180);
1) An arc bounded by a box of height 45, width 90 with a centre point of 50,50, starting
at an angle of 90 degrees traversing through 180 degrees counter clockwise.

2) An arc bounded by a box of height 50, width 50, with a centre point of 45,90 starting
at an angle of 90 degrees traversing through 180 degrees clockwise.

3) An arc bounded by a box of height 50, width 50, with a top left at coordinates of 45,
90, starting at 90 degrees and traversing through 180 degrees counter clockwise.

4) An arc starting at 45 degrees, traversing through 90 degrees clockwise bounded by a
box of height 50, width 50 with a centre point of 90, 180.
 


Question 23)


Which of the following methods can be legally inserted in place of the comment //Method Here ?

class Base{ 

      public void amethod(int i) {  }

} 

public class Scope extends Base{

        public static void main(String argv[]){

        } 

    //Method Here

}

1) void amethod(int i) throws Exception {}
2) void amethod(long i)throws Exception {}
3) void amethod(long i){}
4) public void amethod(int i) throws Exception {}
 


Question 24)


Which of the following will output -4.0

1) System.out.println(Math.floor(-4.7));
2) System.out.println(Math.round(-4.7));
3) System.out.println(Math.ceil(-4.7));
4) System.out.println(Math.Min(-4.7));
 


Question 25)


What will happen if you attempt to compile and run the following code?

Integer ten=new Integer(10); 

Long nine=new Long (9);
System.out.println(ten + nine); 

int i=1;
System.out.println(i + ten);
1) 19 followed by 20
2) 19 followed by 11
3) Error: Can't convert java lang Integer
4) 10 followed by 1
 


Question 26)


If you run the code below, what gets printed out?

String s=new String("Bicycle"); 

int iBegin=1; 

char iEnd=3; 

System.out.println(s.substring(iBegin,iEnd));
1) Bic
2) ic
3) icy
4) error: no method matching substring(int,char)
 


Question 27)

If you wanted to find out where the position of the letter v (ie return 2) in the string s
containing "Java", which of the following could you use?

1) mid(2,s);
2) charAt(2);
3) s.indexOf('v');
4) indexOf(s,'v');


Question 28)

Given the following declarations
String s1=new String("Hello") 

String s2=new String("there"); 

String s3=new String();
Which of the following are legal operations?

1) s3=s1 + s2;
2) s3=s1-s2;
3) s3=s1 & s2
4) s3=s1 && s2


Question 29)

What is the result of the following operation?

System.out.println(4 | 3);

1) 6
2) 0
3) 1
4) 7
 


Question 30)

public class MyClass1 {
public static void main(String argv[]){ } 

/*Modifier at XX */ class MyInner {}
}
What modifiers would be legal at XX in the above code?

1) public
2) private
3) static
4) friend
 


Question 31)


How would you go about opening an image file called MyPicture.jpg

1) Graphics.getGraphics("MyPicture.jpg");
2) Image image=Toolkit.getDefaultToolkit().getImage("MyPicture.jpg");
3) Graphics.openImage("MyPicture");
4) Image m=new Image("MyPicture");
 


Question 32)


An Applet has its Layout Manager set to the default of FlowLayout. What code would be correct to change to another Layout Manager.

1) setLayoutManager(new GridLayout());
2) setLayout(new GridLayout(2,2));
3) setGridLayout(2,2,))
4) setBorderLayout();
 


Question 33)


What will happen when you attempt to compile and run the following code?.

1) It will compile and the run method will print out the increasing value of i.
2) It will compile and calling start will print out the increasing value of i.
3) The code will cause an error at compile time.
4) Compilation will cause an error because while cannot take a parameter of true.
class Background implements Runnable{

  int i=0;

  public int run(){

         while(true){

                i++;

                System.out.println("i="+i);

            } //End while

     }//End run

}//End class
 
 


Question 34)

You have created an applet that draws lines. You have overriden the paint operation and used the graphics drawLine method, and increase one of its parameters to multiple lines across the screen. When you first test the applet you find that the news lines are redrawn, but the old lines are erased. How can you modify your code to allow the old lines to stay on the screen instead of being cleared.

1) Override repaint thus

public void repaint(Graphics g){ 

    paint(g); 

    }

2)Override update thus
public void update(Graphics g) { 

        paint(g); 

        }
3) turn off clearing with the method setClear();

4) Remove the drawing from the paint Method and place in the calling code
 


Question 35)


What will be the result when you attempt to compile and run the following code?.

public class Conv{

    public static void main(String argv[]){ 

        Conv c=new Conv(); 

        String s=new String("ello"); 

        c.amethod(s); 

    } 

public void amethod(String s){ 

    char c='H'; 

    c+=s; 

    System.out.println(c); 

    } 

}

1) Compilation and output the string "Hello"
2) Compilation and output the string "ello"
3) Compilation and output the string elloH
4) Compile time error
 


Question 36)

Given the following code, what test would you need to put in place of the comment line?

//place test here

to result in an output of

Equal
public class EqTest{ 

    public static void main(String argv[]){ 

    EqTest e=new EqTest(); 

    }

EqTest(){ 

    String s="Java"; 

    String s2="java"; 

    //place test here {

        System.out.println("Equal"); 

        }else 

        { 

        System.out.println("Not equal"); 

        }

     } 

}

1) if(s==s2)
2) if(s.equals(s2)
3) if(s.equalsIgnoreCase(s2))
4)if(s.noCaseMatch(s2))
 


Question 37)

Given the following code
import java.awt.*;

public class SetF extends Frame{

public static void main(String argv[]){

        SetF s=new SetF();

        s.setSize(300,200);

        s.setVisible(true);

        }

}
How could you set the frame surface color to pink

1)s.setBackground(Color.pink);
2)s.setColor(PINK);
3)s.Background(pink);
4)s.color=Color.pink
 


Question 38)


How can you change the current working directory using an instance of the File class called FileName?
1) FileName.chdir("DirName")
2) FileName.cd("DirName")
3) FileName.cwd("DirName")
4) The File class does not support directly changing the current directory.
 


Question 39)

If you create a TextField  with a constructor to set it to occupy 5 columns, what difference will it make if you use it with a proportional font (ie Times Roman) or a fixed pitch typewriter style font (Courier).

1)With a fixed font you will see 5 characters, with a  proportional it will depend on the width of the characters
2)With a fixed font you will see 5 characters,with a  proportional it will cause the field to expand to fit the text
3)The columns setting does not affect the number of characters displayed
4)Both will show exactly 5 characters
 


Question 40)


Given the following code how could you invoke the Base constructor that will print out the string "base constructor";

class Base{

        Base(int i){

        System.out.println("base constructor");

        }

        Base(){

        }

}

public class Sup extends Base{

        public static void main(String argv[]){

             Sup s= new Sup();

        //One

        }

        Sup()

        {

            //Two

        }

        public void derived()

        {

            //Three

        }

}

1) On the line After //One put Base(10);
2) On the line After //One put super(10);
3) On the line After //Two put super(10);
4) On the line After //Three put super(10);
 


Question 41)

Given the following code what will be output?
public class Pass{

static int j=20;

public static void main(String argv[]){

        int i=10;

        Pass p = new Pass();

        p.amethod(i);

        System.out.println(i);

        System.out.println(j);

        }

        public void amethod(int x){

        x=x*2;

        j=j*2;

        }

}
1) Error: amethod parameter does not match variable
2) 20 and 40
3) 10 and 40
4) 10, and 20
 


Question 42)


What code placed after the comment //For loop would populate the elements of the array ia[] with values of the variable i.?

public class Lin{

public static void main(String argv[]){

        Lin l = new Lin();

        l.amethod(); 

        }

        public void amethod(){

        int ia[] = new int[4];

                        //Start For loop        

                        {

           ia[i]=i;

           System.out.println(ia[i]);

           }

        }
}
1) for(int i=0; i < ia.length(); i++)
2) for (int i=0; i< ia.length(); i++)
3) for(int i=1; i < 4; i++)
4) for(int i=0; i< ia.length;i++)
 


Question 43)


What will be the result when you try to compile and run the following code?

private class Base{

Base(){

     int i = 100;     

     System.out.println(i);

     }

}

public class Pri extends Base{

static int i = 200;

public static void main(String argv[]){

        Pri p = new Pri();

        System.out.println(i);

        }

}
1) Error at compile time
2) 200
3) 100 followed by 200
4) 100
 


Question 44)

What will the following code print out?
public class Oct{

public static void main(String argv[]){

        Oct o = new Oct();

        o.amethod();

        }

        public void amethod(){

        int oi= 012;

        System.out.println(oi);

        }

}

1)12
2)012
3)10
4)10.0
 
 


Question 45

What will happen when you try compiling and running this code?
public class Ref{

public static void main(String argv[]){

          Ref r = new Ref();

          r.amethod(r);

          }


          public void amethod(Ref r){

          int i=99;

          multi(r);

          System.out.println(i);

          }

          public void multi(Ref r){

          r.i = r.i*2;

          }

}

1) Error at compile time
2) An output of 99
3) An output of 198
4) An error at runtime
 


Question 46)

You need to create a class that will store a unique object elements. You do not need to sort these elements but they must be unique.

What interface might be most suitable to meet this need?

1)Set
2)List
3)Map
4)Vector
 
 


Question 47)

Which of the following will successfully create an instance of the Vector class and add an element?

1) Vector v=new Vector(99);
v[1]=99;
 

2) Vector v=new Vector();
v.addElement(99);
 

3) Vector v=new Vector();
v.add(99);
 

4 Vector v=new Vector(100);
v.addElement("99");
 


Question 48)

You have created a simple Frame and overridden the paint method as follows
public void paint(Graphics g){

 g.drawString("Dolly",50,10);

}


What will be the result when you attempt to compile and run the program?

1) The string "Dolly" will be displayed at the centre of the frame
2) An error at compilation complaining at the signature of the paint method
3) The lower part of the word Dolly will be seen at the top of the form, with the top hidden.
4) The string "Dolly" will be shown at the bottom of the form
 


Question 49)

What will be the result when you attempt to compile this program?
public class Rand{

public static void main(String argv[]){

        int iRand;

        iRand = Math.random();

        System.out.println(iRand);

        }

}
1) Compile time error referring to a cast problem
2) A random number between 1 and 10
3) A random number between 0 and 1
4) A compile time error about random being an unrecognised method


Question 50)

Given the following code
import java.io.*;

public class Th{

        public static void main(String argv[]){

        Th t = new Th();

        t.amethod();

        }

        public void amethod(){

                try{

                ioCall();

                }catch(IOException ioe){}

        }

        

}
What code would be most likely for the body of the ioCall method
1) public void ioCall ()throws IOException{

        DataInputStream din = new DataInputStream(System.in);

        din.readChar();

        }
2) public void ioCall ()throw IOException{

        DataInputStream din = new DataInputStream(System.in);

        din.readChar();

        }
3) public void ioCall (){

        DataInputStream din = new DataInputStream(System.in);

        din.readChar();

        }
4) public void ioCall throws IOException(){     

   DataInputStream din = new DataInputStream(System.in);

        din.readChar();

        }



Question 51)

What will happen when you compile and run the following code?
public class Scope{

private int i;

public static void main(String argv[]){

                Scope s = new Scope();

            s.amethod();

        }//End of main

        public static void amethod(){

                 System.out.println(i);

        }//end of amethod

}//End of class
1) A value of 0 will be printed out
2) Nothing will be printed out
3) A compile time error
4) A compile time error complaining of the scope of the variable i
 


Question 52)


You want to lay out a set of buttons horizontally but with more space between the first button and the rest. You are going to use the GridBagLayout manager to control the way the buttons are set out. How will you modify the way the GridBagLayout acts in order to change the spacing around the first button?
 

1) Create an instance of the GridBagConstraints class, call the weightx() method and then pass the GridBagConstraints instance with the component to the setConstraints method of the GridBagLayout class.

2) Create an instance of the GridBagConstraints class, set the weightx field and then pass the GridBagConstraints instance with the component to the setConstraints method of the GridBagLayout class.

3) Create an instance of the GridBagLayout class, set the weightx field and then call the setConstraints method of the GridBagLayoutClass with the component as a parameter.

4) Create an instance of the GridBagLayout class, call the setWeightx() method and then pass the GridBagConstraints instance with the component to the setConstraints method of the GridBagLayout class.
 


Question 53)


Which of the following can you perform using the File class?

1) Change the current directory
2) Return the name of the parent directory
3) Delete a file
4) Find if a file contains text or binary information
 


Question 54)

Which of the following code fragments will compile without error

1)

public void paint(Graphics g){

  int polyX[] = {20,150,150};

  int polyY[]= {20,20,120};

  g.drawPolygon(polyX, polyY,3);

  }
2)
public void paint(Graphics g){

  int polyX[] = {20,150,150};

  int polyY[]= {20,20,120};

  g.drawPolygon(polyX, polyY);

  }
3)
public void paint(Graphics g){

  int polyX[3] = {20,150,150};

  int polyY[3]= {20,20,120};

  g.drawPolygon(polyX, polyY,3);

  }
4)
public void paint(Graphics g){

  int polyX[] = {20,150,150};

  int polyY[]= {20,20,120};

  drawPolygon(polyX, polyY);

  }



Question 55)

You are concerned about that your program may attempt to use more memory than is available. To avoid this situation you want to ensure that the Java Virtual Machine will run its garbage collection just before you start a complex routine. What can you do to be certain that garbage collection will run when you want .

1) You cannot be certain when garbage collection will run
2) Use the Runtime.gc() method to force garbage collection
3) Ensure that all the variables you require to be garbage collected are set to null
4) Use the System.gc() method to force garbage collection
 


Question 56)

You are using the GridBagLayout manager to place a series of buttons on a Frame. You want to make the size of one of the buttons bigger than the text it contains. Which of the following will allow you to do that?

1) The GridBagLayout manager does not allow you to do this
2) The setFill method of the GridBagLayout class
3) The setFill method of the GridBagConstraints class
4) The fill field of the GridBagConstraints class
 


Question 57)

Which of the following most closely describes a bitset collection?

1) A class that contains groups of unique sequences of bits
2) A method for flipping individual bits in instance of a primitive type
3) An array of boolean primitives that indicate zeros or ones
4) A collection for storing bits as on-off information, like a vector of bits
 


Question 58)


You have these files in the same directory. What will happen when you attempt to compile and run Class1.java if you have not already compiled Base.java

//Base.java
package Base;

class Base{

        protected void amethod(){

                System.out.println("amethod");

        }//End of amethod

}//End of class base
package Class1;

//Class1.java

public class Class1 extends Base{



public static void main(String argv[]){

                Base b = new Base();

                b.amethod();

               }//End of main

}//End of Class1

1) Compile Error: Methods in Base not found
2) Compile Error: Unable to access protected method in base class
3) Compilation followed by the output "amethod"
4)Compile error: Superclass Class1.Base of class Class1.Class1 not found
 


Question 59)

What will happen when you attempt to compile and run the following code
class Base{

private void amethod(int iBase){

        System.out.println("Base.amethod");

        }

}



class Over extends Base{





public static void main(String argv[]){

        Over o = new Over();

        int iBase=0;

        o.amethod(iBase);

        }

        public void amethod(int iOver){

                System.out.println("Over.amethod");

        }



}

1) Compile time error complaining that Base.amethod is private
2) Runtime error complaining that Base.amethod is private
3) Output of Base.amethod
4) Output of Over.amethod()
 
 


Question 60)

You are creating an applet with a Frame that contains buttons. You are using the GridBagLayout manager and you have added Four buttons. At the moment the buttons appear in the centre of the frame from left to right. You want them to appear one on top of the other going down the screen. What is the most appropriate way to do this.
 

1) Set the gridy value of the GridBagConstraint class to a value increasing from 1 to 4
2) set the fill value of the GridBagConstrint class to VERTICAL
3) Set the ipady value of the GridBagConstraint class to a value increasing from 0 to 4
4) Set the fill value of the GridBagLayout class to GridBag.VERTICAL

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