Single-Dimensional Arrays - Liang

6.30 Analyze the following code: public class Test { public static void main(String[] args) { int[] oldList = {1, 2, 3, 4, 5}; reverse(oldList); for (int i = 0; i < oldList.length; i++) System.out.print(oldList[i] + " "); } public static void reverse(int[] list) { int[] newList = new int[list.length]; for (int i = 0; i < list.length; i++) newList[i] = list[list.length - 1 - i]; list = newList; } } A. The program displays 1 2 3 4 5. B. The program displays 1 2 3 4 5 and then raises an ArrayIndexOutOfBoundsException. C. The program displays 5 4 3 2 1. D. The program displays 5 4 3 2 1 and then raises an ArrayIndexOutOfBoundsException.

A. The program displays 1 2 3 4 5. Explanation: The contents of the array oldList have not been changed as result of invoking the reverse method. Initially, list refers to the same heap as oldList array through pass-by-sharing; then newList is generated and stored in a different heap; by list = newList, list now refers to the same heap as newList, and list is no longer related to oldList any more.

6.29 Do the following two programs produce the same result? Program I: public class Test { public static void main(String[] args) { int[] list = {1, 2, 3, 4, 5}; reverse(list); for (int i = 0; i < list.length; i++) System.out.print(list[i] + " "); } public static void reverse(int[] list) { int[] newList = new int[list.length]; for (int i = 0; i < list.length; i++) newList[i] = list[list.length - 1 - i]; list = newList; } } Program II: public class Test { public static void main(String[] args) { int[] oldList = {1, 2, 3, 4, 5}; reverse(oldList); for (int i = 0; i < oldList.length; i++) System.out.print(oldList[i] + " "); } public static void reverse(int[] list) { int[] newList = new int[list.length]; for (int i = 0; i < list.length; i++) newList[i] = list[list.length - 1 - i]; list = newList; } } A. Yes B. No

A. Yes

6.1 What is the representation of the third element in an array called a? A. a[2] B. a(2) C. a[3] D. a(3)

A. a[2]

6.7 Suppose int i = 5, which of the following can be used as an index for array double[] t = new double[100]? (multiple) A. i B. (int)(Math.random() * 100)) C. i + 10 D. i + 6.5 E. Math.random() * 100

A. i B. (int)(Math.random() * 100)) C. i + 10

6.36 The reverse method is defined in this section. What is list1 after executing the following statements? int[] list1 = {1, 2, 3, 4, 5, 6}; int[] list2 = reverse(list1); A. list1 is 1 2 3 4 5 6 B. list1 is 6 5 4 3 2 1 C. list1 is 0 0 0 0 0 0 D. list1 is 6 6 6 6 6 6

A. list1 is 1 2 3 4 5 6

6.38 Which of the following statements are correct to invoke the printMax method in Listing 6.5 in the textbook? A. printMax(1, 2, 2, 1, 4); B. printMax(new double[]{1, 2, 3}); C. printMax(1.0, 2.0, 2.0, 1.0, 4.0); D. printMax(new int[]{1, 2, 3});

A. printMax(1, 2, 2, 1, 4); B. printMax(new double[]{1, 2, 3}); C. printMax(1.0, 2.0, 2.0, 1.0, 4.0); Explanation: The last one printMax(new int [] 1, 2, 3}); is incorrect, because the array must be of the double [ ] type.

6.13 What is the output of the following code? double[] myList = {1, 5, 5, 5, 5, 1}; double max = myList[0]; int indexOfMax = 0; for (int i = 1; i < myList.length; i++) { if (myList[i] > max) { max = myList[i]; indexOfMax = i; } } System.out.println(indexOfMax); A. 0 B. 1 C. 2 D. 3 E. 4

B. 1

6.17 (Tricky) What is output of the following code: public class Test { public static void main(String[] args) { int[] x = {120, 200, 016}; for (int i = 0; i < x.length; i++) System.out.print(x[i] + " "); } } A. 120 200 16 B. 120 200 14 C. 120 200 20 D. 016 is a compile error. It should be written as 16.

B. 120 200 14 Explanation: 016 is an octal number. The prefix 0 indicates that a number is in octal.

6.2 If you declare an array double[] list = {3.4, 2.0, 3.5, 5.5}, list[1] is ________. A. 3.4 B. 2.0 C. 3.5 D. 5.5 E. undefined

B. 2.0

6.5 How many elements are in array double[] list = new double[5]? A. 4 B. 5 C. 6 D. 0

B. 5

6.22 Analyze the following code: public class Test { public static void main(String[] args) { int[] x = {1, 2, 3, 4}; int[] y = x; x = new int[2]; for (int i = 0; i < x.length; i++) System.out.print(x[i] + " "); } } A. The program displays 1 2 3 4 B. The program displays 0 0 C. The program displays 0 0 3 4 D. The program displays 0 0 0 0

B. The program displays 0 0

6.9 Which of the following statements is valid? A. int i = new int(30); B. double d[] = new double[30]; C. int[] i = {3, 4, 3, 2}; D. char[] c = new char(); E. char[] c = new char[4]{'a', 'b', 'c', 'd'};

B. double d[] = new double[30]; C. int[] i = {3, 4, 3, 2}; Explanation: e would be corrected if it is char[] c = new char[]{'a', 'b', 'c', 'd'};

6.32 The JVM stores the array in an area of memory, called _______, which is used for dynamic memory allocation where blocks of memory are allocated and freed in an arbitrary order. A. stack B. heap C. memory block D. dynamic memory

B. heap

6.42 Use the selectionSort method presented in this section to answer this question. What is list1 after executing the following statements? double[] list1 = {3.1, 3.1, 2.5, 6.4}; selectionSort(list1); A. list1 is 3.1, 3.1, 2.5, 6.4 B. list1 is 2.5 3.1, 3.1, 6.4 C. list1 is 6.4, 3.1, 3.1, 2.5 D. list1 is 3.1, 2.5, 3.1, 6.4

B. list1 is 2.5 3.1, 3.1, 6.4

6.35 The reverse method is defined in the textbook. What is list1 after executing the following statements? int[] list1 = {1, 2, 3, 4, 5, 6}; list1 = reverse(list1); A. list1 is 1 2 3 4 5 6 B. list1 is 6 5 4 3 2 1 C. list1 is 0 0 0 0 0 0 D. list1 is 6 6 6 6 6 6

B. list1 is 6 5 4 3 2 1

6.46 Assume int[] list1 = {3, 4, 1, 9, 13}, int[] list2 = {3, 4, 1, 9, 13}, and int[] list3 = {4, 3, 1, 9, 13}, what is System.out.println(java.util.Arrays.equals(list1, list2) + " " + java.util.Arrays.equals(list1, list3)); A. true true B. true false C. false true D. false fasle

B. true false

6.40 If a key is not in the list, the binarySearch method returns _________. A. insertion point B. insertion point - 1 C. -(insertion point + 1) D. -insertion point

C. -(insertion point + 1)

6.19 What will be displayed by the following code? class Test { public static void main(String[] args) { int[] list1 = {1, 2, 3}; int[] list2 = {1, 2, 3}; list2 = list1; list1[0] = 0; list1[1] = 1; list2[2] = 2; for (int i = 0; i < list2.length; i++) System.out.print(list2[i] + " "); } } A. 1 2 3 B. 1 1 1 C. 0 1 2 D. 0 1 3

C. 0 1 2

6.20 What will be displayed by the following code? class Test { public static void main(String[] args) { int[] list1 = {1, 2, 3}; int[] list2 = {1, 2, 3}; list2 = list1; list1[0] = 0; list1[1] = 1; list2[2] = 2; for (int i = 0; i < list1.length; i++) System.out.print(list1[i] + " "); } } A. 1 2 3 B. 1 1 1 C. 0 1 2 D. 0 1 3

C. 0 1 2

6.12 Assume int[] t = {1, 2, 3, 4}. What is t.length? A. 0 B. 3 C. 4 D. 5

C. 4

6.47 Assume int[] scores = {3, 4, 1, 9, 13}, which of the following statement displays all the element values in the array? A. System.out.println(scores); B. System.out.println(scores.toString()); C. System.out.println(java.util.Arrays.toString(scores)); D. System.out.println(scores[0]);

C. System.out.println(java.util.Arrays.toString(scores));

6.24 Analyze the following code. int[] list = new int[5]; list = new int[6]; A. The code has compile errors because the variable list cannot be changed once it is assigned. B. The code has runtime errors because the variable list cannot be changed once it is assigned. C. The code can compile and run fine. The second line assigns a new array to list. D. The code has compile errors because you cannot assign a different size array to list.

C. The code can compile and run fine. The second line assigns a new array to list.

6.15 (for-each loop) Analyze the following code: public class Test { public static void main(String[] args) { double[] x = {2.5, 3, 4}; for (double value: x) System.out.print(value + " "); } } A. The program displays 2.5, 3, 4 B. The program displays 2.5 3 4 C. The program displays 2.5 3.0 4.0 D. The program displays 2.5, 3.0 4.0 E. The program has a syntax error because value is undefined.

C. The program displays 2.5 3.0 4.0

6.25 Analyze the following code: public class Test { public static void main(String[] args) { int[] a = new int[4]; a[1] = 1; a = new int[2]; System.out.println("a[1] is " + a[1]); } } A. The program has a compile error because new int[2] is assigned to a. B. The program has a runtime error because a[1] is not initialized. C. The program displays a[1] is 0. D. The program displays a[1] is 1.

C. The program displays a[1] is 0. Explanation: After executing the statement a = new int[2], a refers to int[2]. The default value for a[0] and a[1] is 0.

6.31 Analyze the following code: public class Test1 { public static void main(String[] args) { xMethod(new double[]{3, 3}); xMethod(new double[5]); xMethod(new double[3]{1, 2, 3}); } public static void xMethod(double[] a) { System.out.println(a.length); } } A. The program has a compile error because xMethod(new double[]{3, 3}) is incorrect. B. The program has a compile error because xMethod(new double[5]) is incorrect. C. The program has a compile error because xMethod(new double[3]{1, 2, 3}) is incorrect. D. The program has a runtime error because a is null.

C. The program has a compile error because xMethod(new double[3]{1, 2, 3}) is incorrect. Explanation: new double[3]{1, 2, 3} should be replaced by new double[]{1, 2, 3}) (anonymous array).

6.23 Analyze the following code: public class Test { public static void main(String[] args) { final int[] x = {1, 2, 3, 4}; int[] y = x; x = new int[2]; for (int i = 0; i < y.length; i++) System.out.print(y[i] + " "); } } A. The program displays 1 2 3 4 B. The program displays 0 0 C. The program has a compile error on the statement x = new int[2], because x is final and cannot be changed. D. The elements in the array x cannot be changed, because x is final.

C. The program has a compile error on the statement x = new int[2], because x is final and cannot be changed. Explanation: The value stored in x is final, but the values in the array are not final.

6.14 Analyze the following code: public class Test { public static void main(String[] args) { int[] x = new int[5]; int i; for (i = 0; i < x.length; i++) x[i] = i; System.out.println(x[i]); } } A. The program displays 0 1 2 3 4. B. The program displays 4. C. The program has a runtime error because the last statement in the main method causes ArrayIndexOutOfBoundsException. D. The program has a compile error because i is not defined in the last statement in the main method.

C. The program has a runtime error because the last statement in the main method causes ArrayIndexOutOfBoundsException. Explanation: After the for loop i is 5. x[5] is out of bounds.

6.8 Analyze the following code. public class Test { public static void main(String[] args) { int[] x = new int[3]; System.out.println("x[0] is " + x[0]); } } A. The program has a compile error because the size of the array wasn't specified when declaring the array. B. The program has a runtime error because the array elements are not initialized. C. The program runs fine and displays x[0] is 0. D. The program has a runtime error because the array element x[0] is not defined.

C. The program runs fine and displays x[0] is 0.

6.10 How can you initialize an array of two characters to 'a' and 'b'? A. char[] charArray = new char[2]; charArray = {'a', 'b'}; B. char[2] charArray = {'a', 'b'}; C. char[] charArray = {'a', 'b'}; D. char[] charArray = new char[]{'a', 'b'};

C. char[] charArray = {'a', 'b'}; D. char[] charArray = new char[]{'a', 'b'};

6.6 What is the correct term for numbers[99]? A. index B. index variable C. indexed variable D. array variable E. array

C. indexed variable

6.3 Which of the following is incorrect? (multiple) A. int[] a = new int[2]; B. int a[] = new int[2]; C. int[] a = new int(2); D. int a = new int[2]; E. int a() = new int[2];

C. int[] a = new int(2); D. int a = new int[2]; E. int a() = new int[2];

6.43 The __________ method sorts the array scores of the double[] type. A. java.util.Arrays(scores) B. java.util.Arrays.sorts(scores) C. java.util.Arrays.sort(scores) D. Njava.util.Arrays.sortArray(scores)

C. java.util.Arrays.sort(scores)

6.27 When you pass an array to a method, the method receives __________. A. a copy of the array B. a copy of the first element C. the reference of the array D. the length of the array

C. the reference of the array

6.33 When you return an array from a method, the method returns __________. A. a copy of the array B. a copy of the first element C. the reference of the array D. the length of the array

C. the reference of the array

6.18 What is output of the following code: public class Test { public static void main(String[] args) { int list[] = {1, 2, 3, 4, 5, 6}; for (int i = 1; i < list.length; i++) list[i] = list[i - 1]; for (int i = 0; i < list.length; i++) System.out.print(list[i] + " "); } } A. 1 2 3 4 5 6 B. 2 3 4 5 6 6 C. 2 3 4 5 6 1 D. 1 1 1 1 1 1

D. 1 1 1 1 1 1

6.16 What is the output of the following code? int[] myList = {1, 2, 3, 4, 5, 6}; for (int i = myList.length - 2; i >= 0; i--) { myList[i + 1] = myList[i]; } for (int e: myList) System.out.print(e + " "); A. 1 2 3 4 5 6 B. 6 1 2 3 4 5 C. 6 2 3 4 5 1 D. 1 1 2 3 4 5 E. 2 3 4 5 6 1

D. 1 1 2 3 4 5

6.44 Assume int[] scores = {1, 20, 30, 40, 50}, what value does java.util.Arrays.binarySearch(scores, 30) return? A. 0 B. -1 C. 1 D. 2 E. -2

D. 2

6.28 Show the output of the following code: public class Test { public static void main(String[] args) { int[] x = {1, 2, 3, 4, 5}; increase(x); int[] y = {1, 2, 3, 4, 5}; increase(y[0]); System.out.println(x[0] + " " + y[0]); } public static void increase(int[] x) { for (int i = 0; i < x.length; i++) x[i]++; } public static void increase(int y) { y++; } } A. 0 0 B. 1 1 C. 2 2 D. 2 1 E. 1 2

D. 2 1 Explanation: Invoking increase(x) passes the reference of the array to the method. Invoking increase(y[0]) passes the value 1 to the method. The value y[0] outside the method is not changed.

6.4 If you declare an array double[] list = {3.4, 2.0, 3.5, 5.5}, the highest index in array list is __________. A. 0 B. 1 C. 2 D. 3 E. 4

D. 3

6.26 The __________ method copies the sourceArray to the targetArray. A. System.copyArrays(sourceArray, 0, targetArray, 0, sourceArray.length); B. System.copyarrays(sourceArray, 0, targetArray, 0, sourceArray.length); C. System.arrayCopy(sourceArray, 0, targetArray, 0, sourceArray.length); D. System.arraycopy(sourceArray, 0, targetArray, 0, sourceArray.length);

D. System.arraycopy(sourceArray, 0, targetArray, 0, sourceArray.length);

6.39 For the binarySearch method in Section 6.9.2, what is low and high after the first iteration of the while loop when invoking binarySearch(new int[]{1, 4, 6, 8, 10, 15, 20}, 11)? A. low is 0 and high is 6 B. low is 0 and high is 3 C. low is 3 and high is 6 D. low is 4 and high is 6 E. low is 0 and high is 5

D. low is 4 and high is 6

6.37 Which of the following declarations are correct? A. public static void print(String... strings, double... numbers) B. public static void print(double... numbers, String name) C. public static double... print(double d1, double d2) D. public static void print(double... numbers) E. public static void print(int n, double... numbers)

D. public static void print(double... numbers) E. public static void print(int n, double... numbers) Explanation: Only one variable-length may be specified in a method and this parameter must be the last parameter. The method return type cannot be a variable-length parameter.

6.34 Suppose a method p has the following heading: public static int[] p() What return statement may be used in p()? A. return 1; B. return {1, 2, 3}; C. return int[]{1, 2, 3}; D. return new int[]{1, 2, 3};

D. return new int[]{1, 2, 3};

6.45 Assume int[] scores = {1, 20, 30, 40, 50}, what value does java.util.Arrays.binarySearch(scores, 3) return? A. 0 B. -1 C. 1 D. 2 E. -2

E. -2

6.41 Use the selectionSort method presented in this section to answer this question. Assume list is {3.1, 3.1, 2.5, 6.4, 2.1}, what is the content of list after the first iteration of the outer loop in the method? A. 3.1, 3.1, 2.5, 6.4, 2.1 B. 2.5, 3.1, 3.1, 6.4, 2.1 C. 2.1, 2.5, 3.1, 3.1, 6.4 D. 3.1, 3.1, 2.5, 2.1, 6.4 E. 2.1, 3.1, 2.5, 6.4, 3.1

E. 2.1, 3.1, 2.5, 6.4, 3.1

6.11 What would be the result of attempting to compile and run the following code? public class Test { public static void main(String[] args) { double[] x = new double[]{1, 2, 3}; System.out.println("Value is " + x[1]); } } A. The program has a compile error because the syntax new double[]{1, 2, 3} is wrong and it should be replaced by {1, 2, 3}. B. The program has a compile error because the syntax new double[]{1, 2, 3} is wrong and it should be replaced by new double[3]{1, 2, 3}; C. The program has a compile error because the syntax new double[]{1, 2, 3} is wrong and it should be replaced by new double[]{1.0, 2.0, 3.0}; D. The program compiles and runs fine and the output "Value is 1.0" is printed. E. The program compiles and runs fine and the output "Value is 2.0" is printed.

E. The program compiles and runs fine and the output "Value is 2.0" is printed Explanation: new double[]{1, 2, 3} is correct. This is the syntax I have not covered in this edition, but will be covered in the future edition. In this question, double[] x = new double[]{1, 2, 3} is equivalent to double[] x = {1, 2, 3};

6.21 Analyze the following code: public class Test { public static void main(String[] args) { int[] x = {1, 2, 3, 4}; int[] y = x; x = new int[2]; for (int i = 0; i < y.length; i++) System.out.print(y[i] + " "); } } A. The program displays 1 2 3 4 B. The program displays 0 0 C. The program displays 0 0 3 4 D. The program displays 0 0 0 0

A. The program displays 1 2 3 4