1. Consider the following method:



public static void tryMe (int [ ] x, int size)

{

 for (int i = 0; i <  size; i++)

 System.out.println( “ [ “ + i + “ ] = “ + x[i]);

}



and the declarations:



int [ ] list = new int [100];

int [ ] score = new int[50];

double [ ] gpa = new double [50];



Which of the following method calls are valid?

A. tryMe(list, 100);

 valid

B. tryMe(list, 75);

 valid

C. tryMe(score, 100);

  Not valid

D. tryMe(score, 49);

 Valid

E. tryMe(gpa, 50);


Not Valid


2.

 A. What does it mean to say an array index is out of bounds?
The index has no value in an array; the array is not large enough to have a value there.

 B. If an array index is outside the bounds, what happens when you run the program?
It fails to run and you get a  ArrayIndexOutOfBoundsException



3. Determine whether the following array declarations are valid. If a declaration is invalid, give a correct declaration.



 A. int [75] list;
int [] list = new int[75];
 B. int size;
      double [] list = new double [size];
int size = 87;
      double [] list = new double [size];
 C. int[ ] test = new int[-10];
int[] test = new int[10];
 D. double[] sales = new double [40];
valid

4. Suppose list is an array of five elements of type int. What is stored in list after the following java code executes?



for (int i = 0; i < 5; i++)

{

 list[ i ] = 2 * i + 5;



 if (i % 2 == 0)

 list[ i ] = list[ i ] - 3;

}
2
7
6
11
10
5. Suppose we have the following two-dimensional array:



int [ ] [ ] temp = { { 6, 8, 12, 9},

       {17, 5, 10, 6},

       {14, 13, 16, 20} };



Write Java statements to accomplish the following. Note: For each statement, you are asked to output a single element.



A. Output the contents of the first row and first column element of temp.
System.out.println(temp[0][0]);
B. Output the contents of the first row and last column element of temp.
System.out.println(temp[0][3]);
C. Output the contents of the last row and first column element of temp.
System.out.println(temp[2][0]);
D. Output the contents of the last row and last column element of temp.
System.out.println(temp[2][3]);




6. The following program has five errors (Which could be compile or logic errors). Note that some errors involve multiple lines. For each statement that contains an error:



 A. Statement the line number containing the error and the reason for the error.

 B. Rewrite the statement so that the statement is correct.



1. public class Errors

2. {

3.  static Scanner console = new Scanner(System.in);

4.

5.  public static void main(String[ ] args)

6.  {

7.  int[ ] myList = new[10] ; int[ ] myList = new[10] ;

8.

9.  for (int i = 0; i <= 10; i++) for (int i = 0; i < 10; i++)

10.  myList = console.nextInt(); myList[i] = console.nextInt();

11.

12. for(int j = 0; j < myList.length(); j++) for(int j = 0; j < myList.length; j++)

13.  System.out.print(myList[ i ] + “ “ ); System.out.print(myList[ j ] + “ “ );

14.  System.out.println();

15. }

16. }





7. What is the exact output of the following program?



public class List

{

 public static void main(String[ ] args)

 {

 int[ ] alpha = new int[ 5 ];



 alpha[ 0 ] = 5;

 for (int i = 1; i < 5; i++)

 {

 alpha[ i ] = 5 * i + 10;

 alpha[ i -1 ]  = alpha [ i ] - 4;

 }



 System.out.print( “List elements: “);



 for (int i = 0; i < 5; i++)

 System.out.print(alpha[ i ] + “ “);

 }

}


List elements: 11 16 21 26 30


8. Write Java statements that do the following:



A. Declare an array alpha of 15 elements of type int.
int[ ] alpha = new int[15];
B. Output the value of the array alpha at index 9.
System.out.println(alpha[9]);
C. Set the value of the array alpha at index 8 to the sum of the elements at indices 5 and 12.
alpha[8] = alpha[5] + alpha[12];
D. Set the value of the array alpha at index 3 to three times the value at index 7 and then subtract by 57.
alpha[3] = 3 * alpha[7] - 57;
E. Output alpha so that five elements per line are printed.

int i = 0;

  while (i < 15)
  {
   System.out.print(alpha[i]);
    i++;

    if (i % 5 == 0)
     System.out.println();
   }


9. Write Java statements that do the following:



A. Declare an array alpha of 10 rows and 20 columns of type int.
int[ ][ ] alpha = new int[10][20];
B. Initialize each element of the array alpha to 5.

int i = 0;
int j = 0;

while (j < 20)
{

   while (i < 10)
   {
    alpha[i][j] = 5;
    i++;
   }

  i = 0;
  j++;
}

C. Store 1 in all elements in the first row, and store 2 in the remaining rows.
int i = 0;

while (i < 20)
{
 alpha[0][i] = 1;
 i++;
}


i = 1;
int j = 0;

while (j < 20)
{

   while (i < 10)
   {
    alpha[i][j] = 2;
    i++;
   }

  i = 1;
  j++;
}
D. Store 5 in all elements in the first column, and the value of each remaining column is twice the value of the previous column.
int i = 0;

while (i < 10)
{
 alpha[i][0] = 5;
 i++;
}


i = 0;
int j = 1;

while (j < 20)
{

   while (i < 10)
   {
    alpha[i][j] = 2 * alpha[i][j-1];
    i++;
   }

  i = 0;
  j++;
}
E. Print the array alpha one row per line with a space between each element.
int i = 0;
int j = 0;

while (i < 10)
{

   while (j < 20)
   {
    System.out.print(alpha[i][j]);
    System.out.print(" ");

    if (j == 19)
     System.out.println();

    j++;
   }

  j = 0;
  i++;
}

10. Write Java statements to define and initialize the following arrays using a single line of code.



A. Array of doubles called heights. Define and initialize the array of the following values: 5.2, 6.3, 5.8, 4.9, 5.2, 5.7, 6.7, 7.1, 5.10, 6.0
 double[ ] heights = {5.2, 6.3, 5.8, 4.9, 5.2, 5.7, 6.7, 7.1, 5.10, 6.0};
B. Array of integers called weights. Define and initialize the array to the following values: 120, 125, 137, 140, 150, 180, 210
int[ ] weights = {120, 125, 137, 140, 150, 180, 210};
C. Array of characters called specialSymbols. Define and initialize the array to the following values: ‘%bodyamp;rsquo;, ‘#’, ‘%’, ‘&’, ‘!’, ‘^’
char[  ] specialSymbols = {‘%bodyamp;rsquo;', ‘#’, ‘%’, ‘&’, ‘!’, ‘^’}
 char[  ] specialSymbols = {'#', '%', '&', '!', '^'};
D. Array of strings called seasons. Define and initialize the array to the following values: “fall”, “winter”, “spring”, “summer”
String[ ] seasons = {"fall", "winter", "spring", "summer"};