Computer Science Unit 7
Identify the correct statement for defining an integer array named numarray of ten elements. a) int[] numarray = new int[9]; b) int[] numarray = new int[10]; c) int[10] numarray; d) int numarray[10];
b) int[] numarray = new int[10];
What is the value of the cnt variable after the execution of the code snippet below? ArrayList<Integer> somenum = new ArrayList<Integer>(); somenum.add(1); somenum.add(2); somenum.add(1); int cnt = 0; for (int index = 0; index < somenum.size(); index++) { if (somenum.get(index) % 2 == 0) { cnt++; } } a) 1 b) 2 c) 3 d) 0
a) 1
What is the value of the count variable after the execution of the given code snippet? ArrayList<Integer> num = new ArrayList<Integer>(); num.add(1); num.add(2); num.add(1); int count = 0; for (int i = 0; i < num.size(); i++) { if (num.get(i) % 2 == 0) { count++; } } a) 1 b) 2 c) 0 d) 3
a) 1
What is the output of the following code? int[][] counts = { { 0, 0, 1 }, { 0, 1, 1, 2 }, { 0, 0, 1, 4, 5 }, { 0, 2 } }; System.out.println(counts[3].length); a) 2 b) 3 c) 4 d) 5
a) 2
What is the output of the given code snippet? int[] mynum = new int[5]; for (int i = 1; i < 5; i++) { mynum[i] = i + 1; System.out.print(mynum[i]); } a) 2345 b) 1234 c) 1345 d) 1111
a) 2345
Which statements are true about the buffer overrun attack launched over the Internet in 1988? I. The buffer overrun exploited a program that was written in C running on the Unix operating system II. The Java programming language generates a run-time exception when buffer overrun occurs III. In recent years computer attacks have lessened a) I, II b) I, III c) II, III d) I, II, III
a) I, II
Why is the following method header invalid? public static int[5] meth(int[] arr, int[] num) a) Methods that return an array cannot specify its size b) Methods cannot have an array as a return type c) Methods cannot have an array as a parameter variable d) Methods cannot have two array parameter variables
a) Methods that return an array cannot specify its size
Which one of the following statements is correct for displaying the value in the second row and the third column of a two-dimensional, size 3 by 4 array? a) System.out.println(arr[1][2]); b) System.out.println(arr[2][3]); c) System.out.println(arr[2][1]); d) System.out.println(arr[3][2]);
a) System.out.println(arr[1][2]);
Which one of the following statements is correct for displaying the value in the third row and the fourth column of a two-dimensional 5 by 6 array? a) System.out.println(arr[2][3]); b) System.out.println(arr[3][4]); c) System.out.println(arr[3][2]); d) System.out.println(arr[4][3]);
a) System.out.println(arr[2][3]);
What should you check for when calculating the largest value in an array list? a) The array list contains at least one element. b) The array list contains at least two elements. c) The array list contains the minimum value in the first element. d) The array list contains the maximum value in the first element.
a) The array list contains at least one element.
What should you check for when calculating the smallest value in an array list? a) The array list contains at least one element. b) The array list contains at least two elements. c) The array list contains the maximum value in the first element. d) The array list contains the minimum value in the first element.
a) The array list contains at least one element.
Consider the following code snippet: public static void check(ArrayList<Integer> chknum1) { int cnt = 0; for(int i = 0; i < chknum1.size(); i++) { if(chknum1.get(i) == 0) { cnt++; } } System.out.println("The total 0 values in the list are: " + cnt); } Which one of the following is true about the check method in the given code snippet? a) The check method counts all the elements with value 0 in an array list passed as a parameter to the method. b) The check method removes all the elements with value 0 from an array list passed as a parameter to the method. c) The check method counts all the elements with value 0 in an array list passed as a parameter to a method and also returns the count. d) The check method adds 0 to the elements of an array list as a parameter to a method and also returns the array list.
a) The check method counts all the elements with value 0 in an array list passed as a parameter to the method.
Which statement is true about the code snippet below? ArrayList<String> names = new ArrayList<String>(); names.add("John"); names.add("Jerry"); ArrayList<String> friends = new ArrayList<String>(names); friends.add("Harry"); a) The final size of names is 2; the final size of friends is 3 b) The final size of names is 3; the final size of friends is 2 c) The final size of names is 3; the final size of friends is 3 d) Compilation error
a) The final size of names is 2; the final size of friends is 3
) Consider the following code snippet: String[] data = { "abc", "def", "ghi", "jkl" }; Using Java 6 or later, which statement grows the data array to twice its size? a) data = Arrays.copyOf(data, 2 * data.length); b) data = Arrays.copyOf(data, 2); c) data = Arrays.copyOf(data, 2 * data); d) data = Arrays.copyOf(data, 2 * data.size());
a) data = Arrays.copyOf(data, 2 * data.length);
) Which code snippet calculates the sum of all the even elements in an array values? a) int sum = 0; for (int i = 0; i < values.length; i++) { if ((values[i] % 2) == 0) { sum += values[i]; } } b) int sum = 0; for (int i = 0; i < values.length; i++) { if ((values[i] % 2) == 0) { sum++; } } c) int sum = 0; for (int i = 0; i < values.length; i++) { if ((values[i] / 2) == 0) { sum += values[i]; } } d) int sum = 0; for (int i = 0; i < values.length; i++) { if ((values[i] / 2) == 0) { sum++; } }
a) int sum = 0; for (int i = 0; i < values.length; i++) { if ((values[i] % 2) == 0) { sum += values[i]; } }
Which one of the following statements is the correct definition for a two-dimensional array of 20 rows and 2 columns of the type integer? a) int[][] num = new int[20][2]; b) int[][] num = new int[2][20]; c) int[][] num = new int[20,2]; d) int[][] num = new int[2,20];
a) int[][] num = new int[20][2];
The enhanced for loop a) is convenient for traversing all elements in an array b) is convenient for traversing elements in a partially filled array c) is only used for arrays of integers d) is used to initialize all array elements to a common value
a) is convenient for traversing all elements in an array
Which one of the following is a valid signature of a method with an integer two-dimensional array parameter of size 10 x 10? a) public static void func(int[][] arr) b) public static void func(int[10][] arr) c) public static void func(int[][10] arr) d) public static void func(int[10][10] arr)
a) public static void func(int[][] arr)
Consider the following code snippet: ArrayList<Double> somedata = new ArrayList<Double>(); somedata.add(10.5); What is the size of the array list somedata after the given code snippet is executed? a) 0 b) 1 c) 10 d) 2
b) 1
Consider the following code snippet: int[][] arr = { { 1, 2, 3, 0 }, { 4, 5, 6, 0 }, { 0, 0, 0, 0 } }; int[][] arr2 = arr; System.out.println(arr2[2][1] + arr2[1][2]); What is the output of the given code snippet on execution? a) 5 b) 6 c) 7 d) 9
b) 6
What is the output of the code snippet below? int[][] arr = { { 1, 2, 3, 0 }, { 4, 5, 6, 0 }, { 0, 0, 0, 0 } }; int val = arr[1][2] + arr[1][3]; System.out.println(val); a) 5 b) 6 c) 7 d) 9
b) 6
What is the value of myArray[1][2] after this code snippet is executed? int count = 0; int[][] myArray = new int[4][5]; for (int i = 0; i < 5; i++) { for (int j = 0; j < 4; j++) { myArray[j][i] = count; count++; } } a) 8 b) 9 c) 19 d) 11
b) 9
Your program needs to store a sequence of integers of unknown length. Which of the following is most suitable to use? a) An array declared as int[] marks; b) A array list declared as ArrayList<Integer> marks = new ArrayList<Integer>(); c) An array declared as int marks[10000]; d) An array declared as int marks[10];
b) A array list declared as ArrayList<Integer> marks = new ArrayList<Integer>();
Which one of the following code snippets accepts the integer input in an array named num1 and stores the odd integers of num1 in another array named oddnum? a) ArrayList<Integer> num1 = new ArrayList<Integer>(); ArrayList<Integer> oddnum = new ArrayList<Integer>(); int data; Scanner in = new Scanner(System.in); for (int i = 0; i < 10; i++) { data = in.nextInt(); num1.add(data); if (num1.get(i) % 2 == 0) { oddnum.add(num1.get(i)); } } b) ArrayList<Integer> num1 = new ArrayList<Integer>(); ArrayList<Integer> oddnum = new ArrayList<Integer>(); int data; Scanner in = new Scanner(System.in); for (int i = 0; i < 10; i++) { data = in.nextInt(); num1.add(data); if (num1.get(i) % 2 != 0) { oddnum.add(num1.get(i)); } } c) ArrayList<Integer> num1 = new ArrayList<Integer>(); ArrayList<Integer> oddnum = new ArrayList<Integer>(); int data; Scanner in = new Scanner(System.in); for (int i = 0; i < 10; i++) { data = in.nextInt(); num1.add(data); if (num1.get(i) % 2 == 0) { oddnum.add(num1[i]); } } d) ArrayList<Integer> num1; ArrayList<Integer> oddnum = new ArrayList<Integer>(); int data; Scanner in = new Scanner(System.in); for (int i = 0; i < 10; i++) { data = in.nextInt(); num1.add(data); if (num1[i] % 2 != 0) { oddnum.add(num1[i]); } }
b) ArrayList<Integer> num1 = new ArrayList<Integer>(); ArrayList<Integer> oddnum = new ArrayList<Integer>(); int data; Scanner in = new Scanner(System.in); for (int i = 0; i < 10; i++) { data = in.nextInt(); num1.add(data); if (num1.get(i) % 2 != 0) { oddnum.add(num1.get(i)); } }
Which statements about array algorithms are true? I. The array algorithms are building blocks for many programs that process arrays II. Java contains ready-made array algorithms for every problem situation III. It is inefficient to make multiple passes through an array if you can do everything in one pass a) I, II b) I, III c) II, III d) I, II, III
b) I, III
Which statements are true regarding the differences between arrays and array lists? I. Arrays are better if the size of a collection will not change II. Array lists are more efficient than arrays III. Array lists are easier to use than arrays a) I, II b) I, III c) II, III d) I, II, III
b) I, III
Which one of the following statements is correct for the given code snippet? int[] number = new int[3]; // Line 1 number[3] = 5; // Line 2 a) Line 2 declares and initializes an array of three elements with value 5. b) Line 2 causes a bounds error because 3 is an invalid index number. c) Line 2 initializes the third element of the array with value 5. d) Line 2 initializes all the elements of the array with value 5.
b) Line 2 causes a bounds error because 3 is an invalid index number.
When the order of the elements is unimportant, what is the most efficient way to remove an element from an array? a) Delete the element and move each element after that one to a lower index. b) Replace the element to be deleted with the last element in the array. c) Replace the element to be deleted with the first element in the array. d) Replace the element with the next element.
b) Replace the element to be deleted with the last element in the array.
Which one of the following is the correct definition for initializing data in a two-dimensional array of three rows and two columns? a) int[][] arr = { { 1, 1, 1 }, { 2, 2, 2 }, }; b) int[][] arr = { { 1, 1 }, { 2, 2 }, { 3, 3 } }; c) int[][] arr = { { 1, 1 } { 2, 2 } { 3, 3 } }; d) int[][] arr = { { 1, 1, 1 } { 2, 2, 2 } { 3, 3, 3 } };
b) int[][] arr = { { 1, 1 }, { 2, 2 }, { 3, 3 } }; c) int[][] arr = { { 1, 1 } { 2, 2 } { 3, 3 } };
When an array myArray is only partially filled, how can the programmer keep track of the current number of elements? a) access myArray.length() b) maintain a companion variable that stores the current number of elements c) access myArray.currentElements() d) access myArray.length() - 1
b) maintain a companion variable that stores the current number of elements
Suppose you wish to process an array of values and eliminate any potential duplicate values stored in the array. Which array algorithms might be adapted for this? a) find the minimum b) remove an element c) add an element d) calculate the sum of the elements
b) remove an element
Babbage's machine for automatically producing printed tables was called a) the slide rule. b) the difference engine. c) the mechanical calculator. d) the cog wheel.
b) the difference engine.
The binary search is faster than the linear search, providing a) the size of the array is a power of two. b) the elements of the array are ordered. c) the elements of the array are unordered. d) the element being searched for is actually in the array.
b) the elements of the array are ordered.
Consider the following code snippet in Java 6 or later: String[] data = { "abc", "def", "ghi", "jkl" }; String[] data2 = Arrays.copyOf(data, data.length - 1); What does the last element of data2 contain? a) "abc" b) "def" c) "ghi" d) "jkl"
c) "ghi"
Consider the following code snippet. What does the array contain at the end of the program? public static fillWithRandomNumbers(double[] values) { double[] numbers = new double[values.length]; for (int i = 0; i < numbers.length; i++) { numbers[i] = Math.random(); } values = numbers; } public static void main(String[] args) { double[] num = new double[20]; fillWithRandomNumbers(num); } a) 20 random numbers b) Undefined data due to compilation error c) 20 zeros because array num is not changed by method d) Array index bound error
c) 20 zeros because array num is not changed by method
Consider the following code snippet: int[][] numarray = { { 3, 2, 3 }, { 0, 0, 0 } }; System.out.print(numarray[0][0]); System.out.print(numarray[1][0]); What is the output of the given code snippet? a) 00 b) 31 c) 30 d) 03
c) 30
What is the output of the following code snippet? int[] myarray = { 10, 20, 30, 40, 50 }; System.out.print(myarray[2]); System.out.print(myarray[3]); a) 1050 b) 2030 c) 3040 d) 4050
c) 3040
What is the output of the code snippet below? int[][] numarray = { { 8, 7, 6 }, { 0, 0, 0 } }; System.out.print(numarray[0][0]); System.out.print(numarray[1][0]); a) 00 b) 87 c) 80 d) 08
c) 80
Consider the following code snippet: int[][] arr = { { 1, 2, 3 }, { 4, 5, 6 } }; int val = arr[0][2] + arr[1][2]; System.out.println(val); What is the output of the given code snippet on execution? a) 5 b) 7 c) 9 d) 10
c) 9
What is the output of the following statements? ArrayList<String> names = new ArrayList<String>(); names.add("Bob"); names.add(0, "Ann"); names.remove(1); names.add("Cal"); names.set(1, "Tony"); for (String s : names) { System.out.print(s + ", "); } a) Cal, Bob, Ann b) Ann, Bob c) Ann, Tony d) Cal, Bob, Tony
c) Ann, Tony
Consider the following code snippet, where the array lists contain elements that are stored in ascending order: ArrayList<Integer> list1 = new ArrayList<Integer>(); ArrayList<Integer> list2 = new ArrayList<Integer>(); . . . int count = 0; for (int i = 0; i < list1.size() && i < list2.size(); i++) { if (list1.get(i) == list2.get(i)) { count++; } } Which one of the following descriptions is correct for the given code snippet? a) The code snippet finds the highest value out of the two array lists. b) The code snippet finds the lowest value out of the two array lists. c) The code snippet compares the values of two array lists and stores the count of total matches found. d) The code snippet adds the values of the two array lists.
c) The code snippet compares the values of two array lists and stores the count of total matches found.
Which statement is true about the code snippet below? ArrayList<String> names = new ArrayList<String>(); names.add("John"); names.add("Jerry"); ArrayList<String> friends = names; friends.add("Harry"); a) The final size of names is 2; the final size of friends is 3 b) The final size of names is 3; the final size of friends is 2 c) The final size of names is 3; the final size of friends is 3 d) Compilation error
c) The final size of names is 3; the final size of friends is 3
Consider the following method: public static int mystery(int length, int n) { int[] result = new int[length]; for (int i = 0; i < result.length; i++) { result[i] = (int) (n * Math.random()); } return result; } Which statement is correct about the code? a) The method works perfectly b) The method returns a random number c) The method return type should be changed to int[] d) The method has a bounds error when the array size is too large
c) The method return type should be changed to int[]
Consider the following code snippet: int val = arr[0][2]; Which value of arr is stored in the val variable? a) The value in the first row and the second column b) The value in the first row and the first column c) The value in the first row and the third column d) The value in the third row and the second column
c) The value in the first row and the third column
Consider the following line of code for calling a method named func1: func1(listData, varData); Which one of the following method headers is valid for func1, where listData is an integer array list and varData is an integer variable? a) public static void func1(int[] listData, int varData) b) public static void func1(ArrayList<Integer> listData, varData) c) public static void func1(ArrayList<Integer> ldata, int vdata) d) public static void func1(int vdata, ArrayList<Integer> ldata)
c) public static void func1(ArrayList<Integer> ldata, int vdata)
Which one of the following is a correct declaration for a method named passAList that has as arguments an array list myList of size 10 and an integer array intArr of size 20, and that modifies the contents of myList and intArr? a) public static void passAList(ArrayList<Integer> myList(10), int[] intArr) b) public static void passAList(ArrayList<Integer> myList, int[20] intArr) c) public static void passAList(ArrayList<Integer> myList, int[] intArr) d) public static void passAList(ArryaList<Integer> myList, int intArr)
c) public static void passAList(ArrayList<Integer> myList, int[] intArr)
Which one of the following is a correct declaration for a method named passAList with the array list num of size 5 as a parameter? a) public static void passAList(ArrayList<Integer> num[5]) b) public static void passAList(ArrayList<Integer> num, 5) c) public static void passAList(ArrayList<Integer> num) d) public static void passAList(num)
c) public static void passAList(ArrayList<Integer> num)
Consider the following code snippet: ArrayList<Integer> num1 = new ArrayList<Integer>(); int data; Scanner in = new Scanner(System.in); for (int i = 0; i < 5; i++) { data = in.nextInt(); num1.add(data); if (data == 0 && num1.size() > 3) { num1.remove(num1.size() - 1); } } System.out.println("size is : " + num1.size()); What is the output of the given code snippet if the user enters 1,2,0,0,1 as the input? a) size is : 1 b) size is : 2 c) size is : 4 d) size is : 0
c) size is : 4
What is the valid range of index values for an array of size 10? a) 0 to 10 b) 1 to 9 c) 1 to 10 d) 0 to 9
d) 0 to 9
How many elements can be stored in a two-dimensional 5 by 6 array? a) 5 b) 6 c) 11 d) 30
d) 30
How many elements can be stored in an array of dimension 2 by 3? a) 2 b) 3 c) 5 d) 6
d) 6
What is the output of the following code snippet? public static int check(ArrayList<Integer> listData) { int sum = 0; for (int i = 0; i < listData.size(); i++) { sum = sum + listData.get(i); } return sum; } public static void main(String[] args) { ArrayList<Integer> vdata = new ArrayList<Integer>(); int rsum; for (int cnt = 0; cnt < 3; cnt++) { vdata.add(cnt + 1); } rsum = check(vdata); System.out.println(rsum); } a) 4 b) 2 c) 3 d) 6
d) 6
What is the output of the following statements? ArrayList<String> cityList = new ArrayList<String>(); cityList.add("London"); cityList.add("New York"); cityList.add("Paris"); cityList.add("Toronto"); cityList.add("Hong Kong"); cityList.add("Singapore"); System.out.print(cityList.size()); System.out.print(" " + cityList.contains("Toronto")); System.out.print(" " + cityList.indexOf("New York")); System.out.println(" " + cityList.isEmpty()); a) 5 true 1 false b) 6 true 2 false c) 5 false 1 false d) 6 true 1 false
d) 6 true 1 false
Which one of the following statements about declaring an array list as a method parameter is true? a) An array list declared as a method parameter should be accompanied with its size. b) An array list declared as a method parameter is a constant value by default. c) An array list value cannot be modified in a method when the array list is declared as a parameter. d) An array list value can be modified inside the method.
d) An array list value can be modified inside the method.
What is the output of the following statements? ArrayList<String> names = new ArrayList<String>(); names.add("Bob"); names.add(0, "Ann"); names.remove(1); names.add("Cal"); names.set(2, "Tony"); for (String s : names) { System.out.print(s + ", "); } a) Cal, Bob, Ann b) Ann, Bob c) Ann, Cal, Tony d) Array list bound error
d) Array list bound error
Consider the following code snippet: public static void main(String[] args) { ArrayList<String> names = new ArrayList<String>(); names.add("John"); names.add("Jerry"); names.add("Janet"); ArrayList<String> names = reverse(names); } public static ArrayList<String> reverse(ArrayList<String> names) { ArrayList<String> result = new ArrayList<String>(); for (int i = names.size() - 1; i >= 0; i--) { result.add(names.get(i)); } return <String>result; } Which statement is true after the main method is executed? a) names contains "Janet", "Jerry", "John" in this order b) names contains "John", "Jerry", "Janet" in this order c) reverse method has a bound error d) Compilation error due to the return statement in reverse method
d) Compilation error due to the return statement in reverse method
What is the output of the following code snippet? ArrayList<Integer> num; num.add(4); System.out.println(num.size()); a) 1 b) 0 c) 4 d) Error because num is not initialized
d) Error because num is not initialized
Consider the following code snippet: ArrayList<Integer> arrList = new ArrayList<Integer>(); for (int i = 0; i < arrList.size(); i++) { arrList.add(i + 3); } What value is stored in the element of the array list at index 0? a) 0 b) 3 c) 6 d) None
d) None
Consider the following line of code: int[] somearray = new int[30]; Which one of the following options is a valid line of code for displaying the twenty-eighth element of somearray? a) System.out.println(somearray[28]); b) System.out.println(somearray(28)); c) System.out.println(somearray(27)); d) System.out.println(somearray[27]);
d) System.out.println(somearray[27]);
Which statement is true about the code snippet below? public static void main(String[] args) { Scanner in = new Scanner(System.in); ArrayList<Double> inputs = new ArrayList<Double>(); int ind = 0; while (in.hasNextDouble()) { inputs.set(ind, in.nextDouble()); ind++; } } a) The code adds all input numbers to the array list b) The code has compile-time error c) The array list is full after 100 numbers are entered d) The code has a run-time error
d) The code has a run-time error
What is the output of the following code snippet? public static void main(String[] args) { String[] arr = { "aaa", "bbb", "ccc" }; mystery(arr); System.out.println(arr[0] + " " + arr.length); } public static void mystery(String[] arr) { arr = new String[5]; arr[0] = "ddd"; } a) ddd 5 b) ddd 3 c) aaa 5 d) aaa 3
d) aaa 3
Select the statement that reveals the logic error in the following method. public static double minimum(double[] data) { double smallest = 0.0; for (int i = 0; i < data.length; i++) { if (data[i] < smallest) { smallest = data[i]; } } return smallest; } a) double m = minimum(new double[] { 1.2, -3.5, 6.6, 2.4 }); b) double m = minimum(new double[] { 1.2, 23.5, 16.6, -23.4 }); c) double m = minimum(new double[] { -10.2, 3.5, 62.6, 21.4 }); d) double m = minimum(new double[] { 12.2, 31.5, 6.6, 2.4 });
d) double m = minimum(new double[] { 12.2, 31.5, 6.6, 2.4 });
Consider the following 2-dimensional array. Select the statement that gives the number of columns in the third row. int[][] counts = { { 0, 0, 1 }, { 0, 1, 1, 2 }, { 0, 0, 1, 4, 5 }, { 0, 2 } }; a) int cols = counts[2].size(); b) int cols = counts.length[2]; c) int cols = counts.length; d) int cols = counts[2].length;
d) int cols = counts[2].length;
) Which code snippet calculates the sum of all the elements in even positions in an array? a) int sum = 0; for (int i = 1; i < values.length; i+=2) { sum++; } b) int sum = 0; for (int i = 0; i < values.length; i++) { sum++; } c) int sum = 0; for (int i = 0; i < values.length; i++) { sum += values[i]; } d) int sum = 0; for (int i = 0; i < values.length; i += 2) { sum += values[i]; }
d) int sum = 0; for (int i = 0; i < values.length; i += 2) { sum += values[i]; }
Which one of the following is the correct header for a method named arrMeth that is called like this: arrMeth(intArray); // intArray is an integer array of size 3 a) public static void arrMeth(int[] ar, int n) b) public static void arrMeth(r[], n) c) public static void arrMeth(int n , int[] ar) d) public static void arrMeth(int[] ar)
d) public static void arrMeth(int[] ar)
Consider the following code snippet: String[] data = { "abc", "def", "ghi", "jkl" }; String [] data2; In Java 6 and later, which statement copies the data array to the data2 array? a) data2 = Arrays.copyOf(data, data2.length); b) data2 = Arrays.copyOf(data, data.length); c) data2 = Arrays.copyOf(data, data.size()); d) data2 = Arrays.copyOf(data);
b) data2 = Arrays.copyOf(data, data.length);
When an integer literal is added to an array list declared as ArrayList<Integer>, Java performs: a) casting b) trimming c) auto-boxing d) auto-fixing
c) auto-boxing
Suppose you wish to use an array to solve a new problem. What is the first step to take in finding a solution? a) structure a program using methods b) adapt a built-in array algorithm c) decompose the problem into steps d) assemble a test program and run it
c) decompose the problem into steps
What is the result of the following code? for (double element : values) { element = 0; } a) The elements of the array values are initialized to zero. b) The elements of the array element are initialized to zero. c) The first element of the array values is initialized to zero. d) The array values is not modified.
d) The array values is not modified.
Which one of the following code snippets accepts the integer input in an array list named num1 and stores the even integers of num1 in another array list named evennum? a) ArrayList<Integer> num1 = new ArrayList<Integer>(); ArrayList<Integer> evennum = new ArrayList<Integer>(); Scanner in = new Scanner(System.in); int data; for (int i = 0; i < 10; i++) { data = in.nextInt(); num1.add(data); if (num1.get(i) % 2 == 0) { evennum.add(num1.get(i)); } } b) ArrayList<Integer> num1 = new ArrayList<Integer>(); ArrayList<Integer> evennum = new ArrayList<Integer>(); Scanner in = new Scanner(System.in); int data; for (int i = 0; i < 10; i++) { data = in.nextInt(); num1.add(data); if (num1.get(i) % 2 != 0) { evennum.add(num1.get(i)); } } c) ArrayList<Integer> num1 = new ArrayList<Integer>(); ArrayList<Integer> evennum = new ArrayList<Integer>(); Scanner in = new Scanner(System.in); int data; for int i = 0; i < 10; i++) { data = in.nextInt(); num1.add(data); if (num1.get(i) % 2 != 0) { evennum[i] = num1[i]; } } d) ArrayList<Integer> num1 = new ArrayList<Integer>(); ArrayList<Integer> evennum = new ArrayList<Integer>(); Scanner in = new Scanner(System.in); int data; for (int i = 0; i < 10; i++) { data = in.nextInt(); num1.add(data); if (num1.get(i) % 2 == 0) { evennum[i] = num1[i]; } }
a) ArrayList<Integer> num1 = new ArrayList<Integer>(); ArrayList<Integer> evennum = new ArrayList<Integer>(); Scanner in = new Scanner(System.in); int data; for (int i = 0; i < 10; i++) { data = in.nextInt(); num1.add(data); if (num1.get(i) % 2 == 0) { evennum.add(num1.get(i)); } }
Complete the following code snippet with the correct enhanced for loop so it iterates over the array without using an index variable. String[] arr = { "abc", "def", "ghi", "jkl" }; ___________________ { System.out.print(str); } a) for (String str : arr) b) for (str : String arr) c) for (str[] : arr) d) for (arr[] : str)
a) for (String str : arr)
Which one of the following statements is a valid initialization of an array named somearray of ten elements? a) int[] somearray = { 0, 1, 2, 3, 4, 5, 6, 7, 8, 9 }; b) int somearray[] = { 0, 1, 2, 3, 4, 5, 6, 7, 8, 9, 10 }; c) int[10] somearray = { 0, 1, 2, 3, 4, 5, 6, 7, 8, 9 }; d) int somearray[10] = { 0, 1, 2, 3, 4, 5, 6, 7, 8, 9 };
a) int[] somearray = { 0, 1, 2, 3, 4, 5, 6, 7, 8, 9 };
In a partially filled array, the number of slots in the array that are not currently used is a) the length of the array minus the number of elements currently in the array b) the number of elements currently in the array minus the length of the array c) the length of the array plus the number of elements currently in the array d) the number of elements currently in the array
a) the length of the array minus the number of elements currently in the array
It may be necessary to "grow" an array when reading inputs because a) the number of inputs may not be known in advance. b) arrays in Java must be resized after every 100 elements. c) arrays are based on powers of two. d) the only alternative is a bounds exception.
a) the number of inputs may not be known in advance.
The following statement gets an element from position 4 in an array: x = a[4]; What is the equivalent operation using an array list? a) x = a.get(4); b) x = a.get(); c) x = a.get[4]; d) x = a[4];
a) x = a.get(4);
Consider the following code snippet: int cnt = 0; int[][] numarray = new int[2][3]; for (int i = 0; i < 3; i++) { for (int j = 0; j < 2; j++) { numarray[j][i] = cnt; cnt++; } } What is the value of numarray[1][2] after the code snippet is executed? a) 2 b) 5 c) 3 d) 4
b) 5
Consider the following code snippet: String[] data = { "123", "ghi", "jkl", "def", "%&*" }; Which statement sorts the data array in ascending order? a) data = Arrays.sort(); b) Arrays.sort(data); c) data = Arrays.sort(data.length); d) data = Arrays.sort(data);
b) Arrays.sort(data);
Which statement is true about the code snippet below? ArrayList<String> names = new ArrayList<String>(); names.add("John"); names.add("Jerry"); ArrayList<String> friends = new ArrayList<String>(names); names.add("Harry"); a) The final size of names is 2; the final size of friends is 3 b) The final size of names is 3; the final size of friends is 2 c) The final size of names is 3; the final size of friends is 3 d) Compilation error
b) The final size of names is 3; the final size of friends is 2
Which one of the following statements is correct about the given code snippet? int[] somearray = new int[6]; for (int i = 1; i < 6; i++) { somearray[i] = i + 1; } a) The for loop initializes all the elements of the array. b) The for loop initializes all the elements except the first element. c) The for loop initializes all the elements except the last element. d) The for loop initializes all the elements except the first and last elements.
b) The for loop initializes all the elements except the first element.
Which one of the following is the correct code snippet for calculating the largest value in an integer array list aList? a) int max = 0; for (int count = 1; count < aList.size(); count++) { if (aList.get(count) > max) { max = aList.get(count); } } b) int max = aList.get(0); for (int count = 1; count < aList.size(); count++) { if (aList.get(count) > max) { max = aList.get(count); } } c) int max = aList[1]; for (int count = 1; count < aList.size();count++) { if (aList.get(count) > max) { max = aList.get(count); } } d) int max = aList.get(0); for (int count = 1; count > aList.size();count++) { if (aList.get(count) >= max) { max = aList.get(count); } }
b) int max = aList.get(0); for (int count = 1; count < aList.size(); count++) { if (aList.get(count) > max) { max = aList.get(count); } }
Which one of the following is the correct code snippet for calculating the largest value in an integer array list arrList of size 10? a) int maximum = 0; for (int counter = 1; counter < arrList.size(); counter++) { if (arrList.get(counter) > maximum) { maximum = arrList.get(counter); } } b) int maximum = arrList.get(0); for (int counter = 1; counter < arrList.size(); counter++) { if (arrList.get(counter) > maximum) { maximum = arrList.get(counter); } } c) int maximum = arrList.get(1); for (int counter = 1; counter < arrList.size(); counter++) { if (arrList.get(counter) > maximum) { maximum = arrList.get(counter); } } d) int maximum = arrList.get(0); for (int counter = 1; counter > arrList.size(); counter++) { if (arrList.get(counter) < maximum) { maximum = arrList.get(counter); } }
b) int maximum = arrList.get(0); for (int counter = 1; counter < arrList.size(); counter++) { if (arrList.get(counter) > maximum) { maximum = arrList.get(counter); } }
Which one of the following statements is true about passing arrays to a method? a) By default, arrays are passed by value to a method b) Arrays, when updated in a called method, are not reflected to the calling method c) By default, arrays are passed by reference to a method d) Arrays are passed only if size is specified as another argument
c) By default, arrays are passed by reference to a method
When a Java program terminates and reports an exception, the error message contains which pieces of useful information? I. The compile and revision control history of the source code changes that caused the error II. The name of the exception that occurred III. The stack trace a) I, II b) I, III c) II, III d) I, II, III
c) II, III
Which statements about the enhanced for loop are true? I. It is suitable for all array algorithms II. It does not allow the contents of the array to be modified III. It does not require the use of an index variable a) I, II b) I, III c) II, III d) I, II, III
c) II, III
that provides the output will be [32, 54, 67.5, 29, 35]? public static void main(String[] args) { double data[] = {32, 54, 67.5, 29, 35}; ______________ System.out.println(str); } a) String str = Arrays.format(data); b) String str = data.toString(); c) String str = Arrays.toString(data); d) String str = str + ", " + data[i];
c) String str = Arrays.toString(data);
Consider the following code snippet: int[][] arr = { { 13, 23, 33 }, { 14, 24, 34 } }; Identify the appropriate statement to display the value 24 from the given array? a) System.out.println(arr[1][2]); b) System.out.println(arr[2][2]); c) System.out.println(arr[1][1]); d) System.out.println(arr[2][1]);
c) System.out.println(arr[1][1]);
What is displayed after executing the given code snippet? int[] mymarks = new int[10]; int total = 0; Scanner in = new Scanner(System.in); for (int cnt = 1; cnt <= 10; cnt++) { System.out.print("Enter the marks: "); mymarks[cnt] = in.nextInt(); total = total + mymarks[cnt]; } System.out.println(total); a) The code snippet displays the total marks of all ten subjects. b) The for loop causes a run-time time error on the first iteration. c) The code snippet causes a bounds error. d) The code snippet displays zero.
c) The code snippet causes a bounds error.
What is the result of executing this code snippet? int[] marks = { 90, 45, 67 }; for (int i = 0; i <= 3; i++) { System.out.println(marks[i]); } a) The code snippet does not give any output. b) The code snippet displays all the marks stored in the array without any redundancy. c) The code snippet causes a bounds error. d) The code snippet executes an infinite loop.
c) The code snippet causes a bounds error.
Java 7 introduced enhanced syntax for declaring array lists, which is termed a) angle brackets. b) method lists. c) diamond syntax. d) symmetric slants.
c) diamond syntax.
Which code snippet finds the largest value in an array that is only partially full? a) double largest = values[0]; for (int i = 1; i < values.length; i++) { if (values[i] > largest) { largest = values[i]; } } b) double largest = values[0]; for (int i = 1; i < values.length; i++) { if (values[i] < largest) { largest = values[i]; } } c) double largest = values[0]; for (int i = 1; i < currSize; i++) { if (values[i] > largest) { largest = values[i]; } } d) double largest = values[0]; for (int i = 1; i < currSize; i++) { if (values[i] < largest) { largest = values[i]; }
c) double largest = values[0]; for (int i = 1; i < currSize; i++) { if (values[i] > largest) { largest = values[i]; } }
Which code snippet prints out the elements in a partially filled array of integers? a) for (int i = 0; i < myArray.length(); i++) { System.out.print(myArray[i]); } b) for (int i = 0; i < myArray.currLength(); i++) { System.out.print(myArray[i]); } c) for (int i = 0; i < currLength; i++) { System.out.print(myArray[i]); } d) for (int i = 0; i < myArray.length(); i++) { System.out.print(myArray[currLength]); }
c) for (int i = 0; i < currLength; i++) { System.out.print(myArray[i]); }
Suppose you wish to write a method that returns the sum of the elements in the partially filled array myArray. Which is a reasonable method header? a) public static int sum(int[] values) b) public static int sum() c) public static int sum(int[] values, int currSize) d) public static int sum(int[] values, int size, int currSize)
c) public static int sum(int[] values, int currSize)
What is true about the following code snippet? public static double[] fillWithRandomNumbers(double[] values) { double[] numbers = new double[values.length]; for (int i = 0; i < numbers.length; i++) { numbers[i] = Math.random(); } return Arrays.copyOf(numbers, numbers.length); } public static void main(String[] args) { double[] num = new double[20]; num = fillWithRandomNumbers(num); } a) The code has a run-time error b) The code has a compilation error c) The code has a logic error d) The code is inefficient
d) The code is inefficient
What is the result of the following definition of an array list? ArrayList<Double> points; a) The statement causes a compile time error as the size of the array list is not defined. b) The statement creates an array list of size 0. c) The statement creates an array list with unlimited size. d) The statement defines an array list reference but leaves its value as null.
d) The statement defines an array list reference but leaves its value as null.
42) Is there any thing wrong with the following code snippet? String[] data = { "abc", "def", "ghi", "jkl" }; String searchedValue = "ghi"; int pos = 0; boolean found = false; while (pos < data.length) { if (data[pos].equals(searchedValue)) { found = true; } else { found = false; } pos++; } if (found) { System.out.println("Found at position: " + pos); } else { System.out.println("Not found"); } a) There is nothing wrong. b) There is compile-time error. c) There is a bounds error. d) There is a logic error.
d) There is a logic error.
When an array reading and storing input runs out of space a) the program must be recompiled with a bigger size for the array. b) the array must be "grown" using the growArray method. c) it automatically resizes to accommodate new elements. d) the array must be "grown" using the new command and the copyOf method.
d) the array must be "grown" using the new command and the copyOf method.
