Chapter 7 Java programming
By default, Java initializes array elements with what value?
a. 0
Subscript numbering always starts at what value?
a. 0
What is the value of scores[2][3] in the following array? int [] [] scores = { {88, 80, 79, 92}, {75, 84, 93, 80}, {98, 95, 92, 94}, {91, 84, 88, 96} };
a. 94
What will be the result of executing the following code? int[] x = {0, 1, 2, 3, 4, 5};
a. An array of 6 values ranging from 0 through 5 and referenced by the variable x will be created
What does the following statement do? double[] array1 = new double[10];
a. Declares array1 to be a reference to an array of double values b. Creates an instance of an array of 10 double values c. Will allow valid subscripts in the range of 0 - 9 d. All of the above ANS: D
Which of the statements are true about the following code? final int ARRAY_SIZE = 10; long[] array1 = new long[ARRAY_SIZE];
a. Declares array1 to be a reference to an array of long values b. Creates an instance of an array of 10 long values c. Will allow valid subscripts in the range of 0 - 9 d. All of the above ANS: D
The following statement creates an ArrayList object. What is the purpose of the <String> notation? ArrayList<String> arr = new ArrayList<String>();
a. It specifies that only String objects may be stored in the ArrayList object.
What would be the results of the following code? int[] x = { 55, 33, 88, 22, 99, 11, 44, 66, 77 }; int a = 10; if(x[2] > x[5]) a = 5; else a = 8;
a. a = 5
When an array is passed to a method:
a. a reference to the array is passed b. it is passed just as an object c. the method has direct access to the original array d. All of the above ANS: D
In memory, an array of String objects
a. consists of elements, each of which is a reference to a String object.
A search algorithm:
a. is a way to locate a specific item in a larger collection of data
You use this method to determine the number of items stored in an ArrayList object.
a. numberItems
This ArrayList class method deletes an item from an ArrayList.
a. remove
What do you call the number that is used as an index to pinpoint a specific element within an array?
a. subscript
What will be the value of x[8] after the following code has been executed? final int SUB = 12; int[] x = new int[SUB]; int y = 100; for(int i = 0; i < SUB; i++) { x[i] = y; y += 10; }
b. 180
What will be the value of x[1] after the following code is executed? int[] x = {22, 33, 44}; arrayProcess(x[1]); ... public static void arrayProcess(int a) { a = a + 5; }
b. 33
What will be returned from the following method? public static float[] getValue(int x)
b. An array of float values
Given the following two-dimensional array declaration, which statement is true? int [][] numbers = new int [6] [9];
b. The array numbers has 6 rows and 9 columns
This ArrayList class method is used to insert an item into an ArrayList.
b. add
Java performs ____________, which means that it does not allow a statement to use a subscript that is outside the range of valid subscripts for the array.
b. array bounds checking
In Java, you do not use the new operator when you use a(n):
b. initialization list
To return an array of long values from a method, use this as the return type for the method.
b. long[]
Which of the following is a correct method header for receiving a two-dimensional array as an argument?
b. public static void passArray(int [][])
In order to do a binary search on an array,
b. the array must first be sorted in ascending order
This indicates the number of elements, or values, the array can hold
b. the array's size declarator
What would be the results of the following code? int[] array1 = new int[25]; ... // Code that will put values in array1 int value = array1[0]; for (int a = 1; a < array1.length; a++) { if (array1[a] < value) value = array1[a]; }
b. value contains the lowest value in array1
The binary search algorithm:
b. will cut the portion of the array being searched in half each time the loop fails to locate the search value
What would be the results after the following code was executed? int[] x = {23, 55, 83, 19}; int[] y = {36, 78, 12, 24}; for(int a = 0; a < x.length; a++) { x[a] = y[a]; y[a] = x[a]; }
b. x[] = {36, 78, 12, 24} and y[] = {36, 78, 12, 24}
What would be the results after the following code was executed? int[] x = {23, 55, 83, 19}; int[] y = {36, 78, 12, 24}; x = y; y = x;
b. x[] = {36, 78, 12, 24} and y[] = {36, 78, 12, 24}
If final int SIZE = 15 and int[] x = new int[SIZE], what would be the range of subscript values that could be used with x[]?
c. 0 through 14
What will be the value of x[1] after the following code is executed? int[] x = {22, 33, 44}; arrayProcess(x); ... public static void arrayProcess(int[] a) { for(int k = 0; k < 3; k++) { a[k] = a[k] + 5; } }
c. 38
What will be the value of x[8] after the following code has been executed? final int SUB = 12; int[] x = new int[SUB]; int y = 20; for(int i = 0; i < SUB; i++) { x[i] = y; y += 5; }
c. 60
For the following code, what would be the value of str[2]? String[] str = {"abc", "def", "ghi", "jkl"};
c. A reference to the String "ghi"
What do you normally use with a partially-filled array?
c. An accompanying integer value that holds the number of items stored in the array
What will be the results of the following code? final int ARRAY_SIZE = 5; double[] x = new double[ARRAY_SIZE]; for(int i = 1; i <= ARRAY_SIZE; i++) { x[i] = 10.0; }
c. An error will occur when the program runs.
A ragged array is:
c. a two-dimensional array where the rows are of different lengths
It is common practice to use a ____________ variable as a size declarator.
c. final
Which of the following for loops is valid, given the following declaration? String[] names = {"abc", "def", "ghi", "jkl"};
c. for (int i = 0; i < names.length; i++) System.out.println(names[i].length());
Which of the following is a valid declaration for a ragged array?
c. int[][] ragged = new int[5][];
Each array in Java has a public field named ____________ that contains the number of elements in the array.
c. length
When an individual element of an array is passed to a method:
c. the method does not have direct access to the original array
The sequential search algorithm:
c. uses a loop to sequentially step through an array, starting with the first element
What would be the results of the following code? final int SIZE = 25; int[] array1 = new int[SIZE]; ... // Code that will put values in array1 int value = 0; for (int a = 0; a < array1.length; a++) { value += array1[a]; }
c. value contains the sum of all the values in array1
What would be the results of the following code? final int SIZE = 25; int[] array1 = new int[SIZE]; ... // Code that will put values in array1 int value = 0; for (int a = 0; a <= array1.length; a++) { value += array1[a]; }
d. This would cause the program to crash
If numbers is a two-dimensional int array that has been initialized and total is an int that has been set to 0, which of the following will sum all the elements in the array?
d. for (int row = 0; row < numbers.length; row++) { for (int col = 0; col < numbers[row].length; col++) total += numbers[row][col]; }
The ArrayList class is in this package.
d. java.util
If numbers is a two-dimensional array, which of the following would give the length of row r?
d. numbers[r].length
You can use this ArrayList class method to replace an item at a specific location in an ArrayList.
d. set
Given that String[] str has been initialized, to get a copy of str[0] with all characters converted to upper case, use the following statement:
d. str[0].toUpperCase();
You can use this ArrayList class method to insert an item at a specific location in an ArrayList.
b. add