Java認證考試試題

2017年Java認證考試試題

　　使用Java語言的先進的面向對象特點，包括方法重載，方法覆蓋，抽象類，接口，final，static和訪問控制;實現文件的輸入輸出(I/O)。下面是小編整理的關于Java認證考試試題，希望大家認真閱讀!

　　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;

　　answer to question 1

　　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

　　answer to question 2

　　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{}

　　answer to question 3

　　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

　　answer to question 4

　　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'

　　answer to question 5

　　question 6)

　　which of the following are keywords or reserved words in java?

　　1) if

　　2) then

　　3) goto

　　4) while

　　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

　　answer to question 16

　　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

　　answer to question 17

　　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 4

　　answer to question 18

　　question 19)

　　what will happend 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 probably output of 'vandeleur' but possible output of 'vandeleur 0 1 2 3'

　　answer to question 19

　　question 20)

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

　　//code start

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