JavaTest.docx

QUESTION: 1

Given the code fragment:

int[][] array2D = {{0, 1, 2}, {3, 4, 5, 6}};
system.out.print(array2D[0].length+ "" );
system.out.print(array2D[1].getClass(). isArray() + "");
system.out.println(array2D[0][1]);

What is the result?

A. 3false1
B. 2true3
C. 2false3
D. 3true1
E. 3false3
F. 2true1
G. 2false1

Answer:  D 

Explanation:

The length of the element with index 0, {0, 1, 2}, is 3. Output: 3
The element with index 1, {3, 4, 5, 6}, is of type array. Output: true
The element with index 0, {0, 1, 2} has the element with index 1: 1. Output: 1

QUESTION:  2

View the exhibit:

public class Student {
   public String name = "";
   public int age = 0;
   public String major = "Undeclared";
   public boolean fulltime = true;

   public void display() {
      System.out.println("Name: " + name + " Major: " + major);
   }

   public boolean isFullTime() {
      return fulltime;
   }
}

Given:

public class TestStudent {
   public static void main(String[] args) {
      Student bob = new Student ();
      Student jian = new Student();
      bob.name = "Bob";
      bob.age = 19;
      jian = bob;
      jian.name = "Jian";
      System.out.println("Bob's Name: " + bob.name);
   }
}

What is the result when this program is executed?

A. Bob's Name: Bob
B. Bob's Name: Jian
C. Nothing prints
D. Bob’s name   

Answer:  B 

Explanation:
After the statement jian = bob; the jian will reference the same object as bob.

QUESTION:  3

Given the code fragment:

String valid = "true";
if (valid)
   System.out.println(“valid”);
else
   System.out.println("not valid");

What is the result?

A. Valid
B. not valid
C. Compilation fails
D. An IllegalArgumentException is thrown at run time

Answer:  C

Explanation:

In segment 'if (valid)' valid must be of type boolean, but it is a string. This makes the compilation fail.

QUESTION:  4

Given:

public class ScopeTest {
   int z;
   public static void main(String[] args){
      ScopeTest myScope = new ScopeTest();
      int z = 6; System.out.println(z);
      myScope.doStuff();
      System.out.println(z);
      System.out.println(myScope.z);
   }
   void doStuff() {
      int z = 5; doStuff2();
      System.out.println(z);
}
   void doStuff2() {
      z=4;
   }
}

What is the result?  

A. 6 5 6 4
B. 6 5 5 4
C. 6 5 6 6
D. 6 5 6 5  

Answer:  A 

Explanation:
Within main z is assigned 6. z is printed.
Output: 6 Within doStuff z is assigned 5.
DoStuff2 locally sets z to 4 (but MyScope.z is set to 4), but in Dostuff z is still 5. z is printed.
Output: 5 Again z is printed within main (with local z set to 6).
Output: 6 Finally MyScope.z is printed. MyScope.z has been set to 4 within doStuff2(). Output: 4

QUESTION:  5

Which  two  are  valid  instantiations  and  initializations  of  a  multi-dimensional array?   

A. int[][] array 2D = {{0, 1, 2, 4} {5, 6}};
B. int[][] array2D = new int[2][2];
     array2D[0][0] = 1;
     array2D[0][1] = 2;
     array2D[1][0] = 3;
     array2D[1][1] = 4;
C. int[][][] array3D = {{0, 1}, {2, 3}, {4, 5}};
D. int[][][] array3D = new int[2][2][2];
     array3D[0][0] = array;
     array3D[0][1] = array;
     array3D[1][0] = array;
     array3D[0][1] = array;
E. int[][] array2D = {0, 1};

Answer:  B, D 

Explanation:
In the Java programming language, a multidimensional array is simply an array whose components are themselves arrays.

QUESTION:  6

An unchecked exception occurs in a method dosomething() Should other code be added in the dosomething() method for it to compile and execute?   

A. The Exception must be caught
B. The Exception must be declared to be thrown.
C. The Exception must be caught or declared to be thrown.
D. No other code needs to be added.   

Answer:  C 

Explanation:

Valid Java programming language code must honor the Catch or Specify Requirement. This means that code that might throw certain exceptions must be enclosed by either of the following: * A try statement that catches the exception. The try must provide a handler for the exception, as described in Catching and Handling Exceptions. * A method that specifies that it can throw the exception. The method must provide a throws clause that lists the exception, as described in Specifying the Exceptions Thrown by a Method. Code that fails to honor the Catch or Specify Requirement will not compile.   

QUESTION:  7

Given the code fragment:

int b = 4; b -- ;
System.out.println (-- b);
System.out.println(b);

What is the result?   

A. 2 2
B. 1 2
C. 3 2
D. 3 3

Answer:  A 

Explanation:

Variable b is set to 4. Variable b is decreased to 3. Variable b is decreased to 2 and then printed. Output: 2 Variable b is printed. Output: 2

QUESTION:  8

Given the code fragment:

interface SampleClosable {
   public void close () throws java.io.IOException;
}

Which three implementations are valid?   

A. public class Test implements SampleCloseable { public void close() throws java.io.IOException { / / do something } }

B. public class Test implements SampleCloseable { public void close() throws Exception { / / do something }

C. public class Test implements SampleCloseable { public void close() throws java.io.FileNotFoundException { / / do something } }

D.  public class Test extends SampleCloseable { public void close() throws java.IO.IOException { / / do something } }   

E. public class Test implements SampleCloseable { public void close()  / / do something } }

Answer:  A, C, E 

Explanation:

A: Throwing the same exception is fine.
C: Using a subclass of java.io.IOException (here java.io.FileNotFoundException) is fine
E: Not using a throw clause is fine.

QUESTION: 9 

Given the code fragment: 

Int[][] array = {{0},{0,1},{0,2,4},{0,3,6,9},{0,4,8,12,16}};
Systemout.printIn(array [4] [1]);
System.out.printIn (array) [1][4]); 
int[][] array = {{0},{0,1},{0,2,4},{0,3,6,9},{0,4,8,12,16}};
System.out.println(array [4][1]);
System.out.println(array) [1][4]); 

What is the result? 

A. 4 Null
B. Null 4
C. An IllegalArgumentException is thrown at run time
D. 4 An ArrayIndexOutOfBoundException is thrown at run time 

Answer: D

Explanation:
The first println statement, System.out.println(array [4][1]);, works fine. It selects theelement/array with index 4, {0, 4, 8, 12, 16}, and from this array it selects the element with index 1,4. Output: 4 The second println statement, System.out.println(array) [1][4]);, fails. It selects the array/elementwith index 1, {0, 1}, and from this array it try to select the element with index 4. This causes anexception.  Output: 4 Exception in thread "main" java.lang.ArrayIndexOutOfBoundsException: 4

QUESTION: 10 

Given: 

public class DoCompare1 {
   public static void main(String[] args) {  
      String[] table = {"aa", "bb", "cc"}; 
      for (String ss: table) { 
         int ii = 0; 
         while (ii < table.length) { 
            System.out.println(ss + ", " + ii); 
            ii++; 
         }
      }
   }
} 

How many times is 2 printed as a part of the output? 

A. Zero
B. Once
C. Twice
D. Thrice
E. Compilation fails. 

Answer: D

Explanation:
The for statement, for (String ss: table), is executed one time for each of the threeelements in table. The while loop will print a 2 once for each element. 

Output:
aa, 0
aa, 1
aa, 2
bb, 0
bb, 1
bb, 2
cc, 0
cc, 1
cc, 2

QUESTION: 11

Given: 

import java.io.IOException; 
public class Y { 
   public static void main(String[] args) {
      try { 
      doSomething();
      }  catch (RuntimeException e) { 
         System.out.println(e); 
      } 
   }
   static void doSomething() { 
      if (Math.random() > 0.5)
         throw new IOException(); 
      throw new RuntimeException(); 
   } 
} 

Which two actions, used independently, will permit this class to compile? 

A. Adding throws IOException to the main() method signature
B. Adding throws IOException to the doSoomething() method signature
C. Adding throws IOException to the main() method signature and to the dosomething() method
D. Adding throws IOException to the dosomething() method signature and changing the catchargument to IOException
E. Adding throws IOException to the main() method signature and changing the catch argument toIOException 

Answer: C, D

Explanation:
The IOException must be caught or be declared to be thrown. We must add a throws exception to the doSomething () method signature (static voiddoSomething() throws IOException). Then we can either add the same throws IOException to the main method (public static voidmain(String[] args) throws IOException), or change the catch statement in main to IOException.

QUESTION: 12

Given: 

class X { 
   String str = "default"; 
   X(String s) {
      str = s;
   } 
   void print () {
      System.out.println(str);
   }  
   public static void main(String[] args) {
      new X("hello").print();
   }
}

What is the result? 

A. hello
B. default
C. Compilation fails
D. The program prints nothing
E. An exception is thrown at run time 

Answer: A

Explanation:
The program compiles fine. The program runs fine. The output is: hello.

QUESTION: 13

Given: 

public class SampleClass { 
   public static void main(String[] args) {
      AnotherSampleClass asc = new AnotherSampleClass();
      SampleClass sc = new SampleClass(); // TODO code application logic here 
   }
}
class AnotherSampleClass extends SampleClass {  } 

Which statement, when inserted into line "// TODO code application logic here ", is valid change? 

A. asc = sc;
B. sc = asc;
C. asc = (object) sc;
D. asc = sc.clone () 

Answer: B

Explanation:
Works fine. 

QUESTION: 14

Given the code fragment: 

System.out.println("Result: " + 2 + 3 + 5);
System.out.println("Result: " + 2 + 3 * 5); 

What is the result? 

A. Result: 10 Result: 30
B. Result: 10 Result: 25
C. Result: 235 Result: 215
D. Result: 215 Result: 215
E. Compilation fails 

Answer: C

Explanation:
First line:
System.out.println("Result: " + 2 + 3 + 5);
String concatenation is produced. 

Second line:
System.out.println("Result: " + 2 + 3 * 5);
3*5 is calculated to 15 and is appended to string 2. Result 215. 
The output is:
Result: 235
Result: 215 

Note #1:
To produce an arithmetic result, the following code would have to be used: System.out.println("Result: " + (2 + 3 + 5));
System.out.println("Result: " + (2 + 1 * 5));
run:
Result: 10
Result: 7 

Note #2:
If the code was as follows: 
System.out.println("Result: " + 2 + 3 + 5");
System.out.println("Result: " + 2 + 1 * 5"); 
The compilation would fail. There is an unclosed string literal, 5", on each line.

QUESTION: 15 

Which code fragment is illegal?

A. class Base1 {
      abstract class Abs1 { }
  }
B. abstract class Abs1 {
       void doit () { }
  }
C. class Basel {
       abstract class Abs1 extends Basel { }
  }
D. abstract int var1 = 89; 

Answer: D

Explanation:
The abstract keyword cannot be used to declare an int variable.  The abstract keyword is used to declare a class or method to be abstract[3]. An abstract method has no implementation; all classes containing abstract methods must themselves be abstract, although not all abstract classes have abstract methods.

QUESTION: 16 

Given the code fragment:

int a = 0;
a++;
System.out.println(a++);
System.out.println(a); 

What is the result? 

A.  1 2
B.  0 1
C.  1 1
D.  2 2 

Answer: A

Explanation:
The first println prints variable a with value 1 and then increases the variable to 2.

QUESTION: 17

Given: 

public class x{
   public static void main (string [] args){
      String theString = "Hello World";
      System.out.println(theString.charAt(11)); 
   }
} 

What is the result?

A. There is no output
B. d is output
C. A StringIndexOutOfBoundsException is thrown at runtime
D. An ArrayIndexOutOfBoundsException is thrown at runtime
E. A NullPointException is thrown at runtime
F. A StringArrayIndexOutOfBoundsException is thrown at runtime 

Answer: C