JAVA题库:格林模拟试题一
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 keywords or reserved words in Java?
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)Which of the following statements are true?
1) Methods cannot be overriden to be more private
2) static methods cannot be overloaded
3) private methods cannot be overloaded
4) An overloaded method cannot throw exceptions not checked in the base class
Question 17)What will happen if you attempt to compile and run the following code?
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;
}
}
1) Compile and run without error
2) Compile time Exception
3) Runtime Exception
Question 18)Which of the following statements are true?
1) System.out.println( -1 >>> 2);will output a result larger than 10
2) System.out.println( -1 >>> 2); will output a positive number
3) System.out.println( 2 >> 1); will output the number 1
4) System.out.println( 1 <<< 2); will output the number
Question 19)What will happen when you attempt to compile and run the following code?
public class Tux extends Thread{
static String sName = "vandeleur";
public static void main(String argv[]){
Tux t = new Tux();
t.piggy(sName);
System.out.println(sName);
}
public void piggy(String sName){
sName = sName + " wiggy";
start();
}
public void run(){
for(int i=0;i < 4; i++){
sName = sName + " " + i;
}
}
}
1) Compile time error
2) Compilation and output of "vandeleur wiggy"
3) Compilation and output of "vandeleur wiggy 0 1 2 3"
4) Compilation and output of either "vandeleur", "vandeleur 0", "vandeleur 0 1" "vandaleur 0 1 2" or "vandaleur 0 1 2 3"
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)Which statement is true of the following code?
public class Agg{
public static void main(String argv[]){
Agg a = new Agg();
a.go();
}
public void go(){
DSRoss ds1 = new DSRoss("one");
ds1.start();
}
}
class DSRoss extends Thread{
private String sTname="";
DSRoss(String s){
sTname = s;
}
public void run(){
notwait();
System.out.println("finished");
}
public void notwait(){
while(true){
try{
System.out.println("waiting");
wait();
}catch(InterruptedException ie){}
System.out.println(sTname);
notifyAll();
}
}
}
1) It will cause a compile time error
2) Compilation and output of "waiting"
3) Compilation and output of "waiting" followed by "finished"
4) Runtime error, an exception will be thrown
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) Compile time error
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)What will happen when you attempt to compile and run the following code?
public class Holt extends Thread{
private String sThreadName;
public static void main(String argv[]){
Holt h = new Holt();
h.go();
}
Holt(){}
Holt(String s){
sThreadName = s;
}
public String getThreadName(){
return sThreadName;
}
public void go(){
Holt first = new Holt("first");
first.start();
Holt second = new Holt("second");
second.start();
}
public void start(){
for(int i = 0; i < 2; i ++){
System.out.println(getThreadName() +i);
try{
Thread.sleep(100);
}catch(InterruptedException e){System.out.println(e.getMessage());}
}
}
}
1) Compile time error
2) Output of first0, second0, first0, second1
3) Output of first0, first1, second0, second1
4) Runtime error
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?.
class Background implements Runnable{
int i=0;
public int run(){
while(true){
i++;
System.out.println("i="+i);
} //End while
return 1;
}//End run
}//End class
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.
Question 34)Which of the following statements about this code are true?
public class Morecombe{
public static void main(String argv[]){
Morecombe m = new Morecombe();
m.go(new Turing(){});
}
public void go(Turing t){
t.start();
}
}
class Turing extends Thread{
public void run(){
for(int i =0; i < 2; i++){
System.out.println(i);
}
}
}
1) Compilation error due to malformed parameter to go method
2) Compilation error, class Turing has no start method
3) Compilation and output of 0 followed by 1
4) Compilation but runtime error
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 the string 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 result in the population of every element of the array ia[] with a value from 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() -1; 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 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 frame, with the top hidden.
4) The string "Dolly" will be shown at the bottom of the frame.
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 statement is true of the following code?
public class Rpcraven{
public static void main(String argv[]){
Pmcraven pm1 = new Pmcraven("One");
pm1.run();
Pmcraven pm2 = new Pmcraven("Two");
pm2.run();
}
}
class Pmcraven extends Thread{
private String sTname="";
Pmcraven(String s){
sTname = s;
}
public void run(){
for(int i =0; i < 2 ; i++){
try{
sleep(1000);
}catch(InterruptedException e){}
yield();
System.out.println(sTname);
}
}
}
1) Compile time error, class Rpcraven does not import java.lang.Thread
2) Output of One One Two Two
3) Output of One Two One Two
4) Compilation but no output at runtime
Question 55)You are concerned 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 GridBagConstraints class to a value increasing from 1 to 4
2) set the fill value of the GridBagConstraints class to VERTICAL
3) Set the ipady value of the GridBagConstraints class to a value increasing from 0 to 4
4) Set the fill value of the GridBagLayouts class to GridBag.VERTICAL