Chapter 7 Single-Dimensional Arrays
Section 7.2 Array Basics
3. Once an array is created, its size .
a. can be changed
b. is fixed
c. is not determined
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Section 7.2.1 Declaring Array Variables
3. Which of the following are correct to declare an array of int values?
a. int[] a;
b. int a[];
c. int a;
d. double[] a;
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Section 7.2.2 Creating Arrays
3. Which of the following are incorrect?
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];
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4. If you declare an array double[] list = new double[5], the highest index in array list is .
a. 0
b. 1
c. 2
d. 3
e. 4
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Section 7.2.3 Array Size and Default Values
5. How many elements are in array double[] list = new double[5]?
a. 4
b. 5
c. 6
d. 0
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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.
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Section 7.2.4 Accessing Array Elements
6. What is the correct term for numbers[99]?
a. index
b. index variable
c. indexed variable
d. array variable
e. array
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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)
7. Suppose int i = 5, which of the following can be used as an index for array double[] t = new double[100]?
a. i
b. (int)(Math.random() * 100))
c. i + 10
d. i + 6.5
e. Math.random() * 100
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Section 7.2.5 Array Initializers
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
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9. Which of the following statements are 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();
a.
0
b.
3
c.
4
d.
5
a.
0
b.
1
c.
2
d.
3
e.
4
e. char[] c = new char[4]{‘a’, ‘b’, ‘c’, ‘d’};
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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[2]; charArray[0] = ‘a’; charArray[1] = ‘b’;
12. Assume int[] t = {1, 2, 3, 4}. What is t.length?
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Section 7.2.6 Processing Arrays
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);
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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.
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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
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Section 7.2.7 Foreach Loops
15. 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.
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Section 7.3 Case Study: Analyzing Numbers
17. 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.
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Section 7.4 Case Study: Deck of Cards
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
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Section 7.5 Copying Arrays
20. In the following code, what is the output for list2?
public 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
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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 < 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
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24. 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.
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25. 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.
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26. 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.
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27. 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);
21. In the following code, what is the output for list1?
public 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
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23. 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
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Section 7.6 Passing Arrays to Methods
29. 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
31. 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.
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32. 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.
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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.
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30. 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};
for (int i = 0; i < list.length; i++)
System.out.print(list[i] + ” “);
}
}
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
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28. 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
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33. 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
19. Which of the following is correct?
a. String[] list = new String{“red”, “yellow”, “green”};
b. String[] list = new String[]{“red”, “yellow”, “green”};
c. String[] list = {“red”, “yellow”, “green”};
d. String list = {“red”, “yellow”, “green”};
e. String list = new String{“red”, “yellow”, “green”};
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Section 7.7 Returning an Array from a Method
34. 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
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35. 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};
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36. 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
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37. 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
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Section 7.9 Variable–Length Argument Lists
38. 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)
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39. Which of the following statements are correct to invoke the printMax method in Listing 7.5 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});
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Section 7.10 Searching Arrays
40. For the binarySearch method in Section 7.10.2, 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 5 and high is 5
c. low is 3 and high is 6
d. low is 4 and high is 6
e. low is 6 and high is 5
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41. 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
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Section 7.11 Sorting Arrays
42. 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
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43. 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
a.
0
b.
–1
c.
1
d.
2
e.
–2
a.
0
b.
–1
c.
1
d.
2
e.
–2
c. list1 is 6.4, 3.1, 3.1, 2.5
d. list1 is 3.1, 2.5, 3.1, 6.4
Section 7.12 The Arrays Class
44. 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. java.util.Arrays.sortArray(scores)
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45. Assume int[] scores = {1, 20, 30, 40, 50}, what value does java.util.Arrays.binarySearch(scores, 30) return?
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46. Assume int[] scores = {1, 20, 30, 40, 50}, what value does java.util.Arrays.binarySearch(scores, 3) return?
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47. Assume int[] scores = {1, 20, 30, 40, 50}, what is the output of
System.out.println(java.util.Arrays.toString(scores))?
a. {1, 20, 30, 40, 50}
b. [1, 20, 30, 40, 50]
c. {1 20 30 40 50}
d. [1 20 30 40 50]
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Section 7.13 Command–Line Arguments
48. How can you get the word “abc” in the main method from the following call?
java Test “+” 3 “abc” 2
a. args[0]
b. args[1]
c. args[2]
d. args[3]
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a.
3
b.
1
c.
1 2 3
d.
1 2
49. Given the following program:
public class Test {
public static void main(String[] args) {
for (int i = 0; i < args.length; i++) {
System.out.print(args[i] + ” “);
}
}
}
What is the output, if you run the program using
java Test 1 2 3
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50. Which code fragment would correctly identify the number of arguments passed via the command line to a Java
application, excluding the name of the class that is being invoked?
a. int count = args.length;
b. int count = args.length – 1;
c. int count = 0; while (args[count] != null) count ++;
d. int count=0; while (!(args[count].equals(“”))) count ++;
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51. Which correctly creates an array of five empty Strings?
a. String[] a = new String [5];
b. String[] a = {“”, “”, “”, “”, “”};
c. String[5] a;
d. String[ ] a = new String [5]; for (int i = 0; i < 5; a[i++] = null);
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52. Analyze the following code:
public class Test {
public static void main(String argv[]) {
System.out.println(“argv.length is ” + argv.length);
}
}
a. The program has a compile error because String argv[] is wrong and it should be replaced by String[] args.
b. The program has a compile error because String argv[] is wrong and it should be replaced by String args[].
c. If you run this program without passing any arguments, the program would have a runtime error because argv is
null.
d. If you run this program without passing any arguments, the program would display argv.length is 0.
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53. Which of the following is the correct header of the main method?
a. public static void main(String[] args)
b. public static void main(String args[])
c. public static void main(String[] x)
d. public static void main(String x[])
e. static void main(String[] args)