CHP 7
Suppose array a is int[] a = {1, 2, 3}, what is a[0] - a[2]?
-2
Assume double[] scores = {1, 2, 3, 4, 5}, what value does java.util.Arrays.binarySearch(scores, 3.5) return?
-4
________ declares an array of char.
A) char chars[] D) char[] chars
* If you declare an array double[] list = {3.4, 2.0, 3.5, 5.5}, list[1] is ________.
B. 2.0
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
C. 1 2 3
Assume int[] t = {1, 2, 3, 4}. What is t.length?
C. 4
Analyze the following code. int[] list = new int[5]; list = new int[6];
C. The code can compile and run fine. The second line assigns a new array to list.
* What is the correct term for numbers[99]?
C. indexed variable
* Which of the following is incorrect?
C. int[] a = new int(2); D. int a = new int[2]; E. int a() = new int[2];
Which of the following declarations are correct?
D. public static void print(double... numbers) E. public static void print(int n, double... numbers)
Binary search can be applied on an unsorted list.
false
The array index is not limited to int type.
false
The array size is specified when the array is declared.
false
The element in the array must be of a primitive data type.
false
The name length is a method in an array.
false
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;
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
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);
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);
B. 1
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] + " "); } }
B. 120 200 14
Which correctly creates an array of five empty Strings?
B. String[] a = {"", "", "", "", ""};
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] + " "); } }
B. The program displays 0 0
Assume int[] scores = {1, 20, 30, 40, 50}, what is the output of System.out.println(java.util.Arrays.toString(scores))?
B. [1, 20, 30, 40, 50]
If a key is not in the list, the binarySearch method returns _________.
C. -(insertion point + 1)
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] + " "); } }
C. 0 1 2
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] + " "); } }
C. 0 1 2
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]); } }
C. The program displays a[1] is 0.
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); } }
C. The program has a compile error because xMethod(new double[3]{1, 2, 3}) is incorrect.
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] + " "); } }
C. The program has a compile error on the statement x = new int[2], because x is final and cannot be changed.
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]); } }
C. The program has a runtime error because the last statement in the main method causes ArrayIndexOutOfBoundsException.
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]); } }
C. The program runs fine and displays x[0] is 0.
How can you initialize an array of two characters to 'a' and 'b'?
C. char[] charArray = {'a', 'b'}; D. char[] charArray = new char[]{'a', 'b'};
The __________ method sorts the array scores of the double[] type.
C. java.util.Arrays.sort(scores)
When you pass an array to a method, the method receives __________.
C. the reference of the array
When you return an array from a method, the method returns __________.
C. the reference of the array
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] + " "); } }
D. 1 1 1 1 1 1
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 + " ");
D. 1 1 2 3 4 5
Assume int[] scores = {1, 20, 30, 40, 50}, what value does java.util.Arrays.binarySearch(scores, 30) return?
D. 2
* If you declare an array double[] list = {3.4, 2.0, 3.5, 5.5}, the highest index in array list is __________.
D. 3
Suppose a method p has the following heading: public static int[] p() What return statement may be used in p()?
D. return new int[]{1, 2, 3};
4. Consider the following code fragment: int[] list = new int[10]; for (int i = 0; i <= list.length; i++) { � list[i] = (int)(Math.random() * 10); } Which of the following statements is true? a. list.length must be replaced by 10 b. The loop body will execute 10 times, filling up the array with random numbers. c. The loop body will execute 10 times, filling up the array with zeros. d. The code has a runtime error indicating that the array is out of bound.
D.The code has a runtime error indicating that the array is out of bound.
Assume int[] scores = {1, 20, 30, 40, 50}, what value does java.util.Arrays.binarySearch(scores, 3) return?
E. -2
Analyze the following code: public class Test { � public static void main(String[] args) { ��� int[] x = {0, 1, 2, 3, 4, 5}; ��� xMethod(x, 5); � } � public static void xMethod(int[] x, int length) { ��� for (int i = 0; i < length; i++) ����� System.out.print(" " + x[i]); � } }
The program displays 0 1 2 3 4.
The array index of the first element in an array is 0.
true
The arraycopy method does not allocate memory space for the target array. The target array must already be created with memory space allocated.
true
You can use the operator == to check whether two variables refer to the same array.
true
x.length does not exist if x is null.
true
Assume the signature of the method xMethod is as follows. public static void xMethod(double[] a) Which of the following could be used to invoke xMethod?
xMethod(new double[2]);
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
How can you get the word "abc" in the main method from the following call? java Test "+" 3 "abc" 2
C. args[2]
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?
E. 2.1, 3.1, 2.5, 6.4, 3.1
Which of the following are valid array declarations?
char[] charArray = new char[26];
Which of the following is correct to create an array?
int[] m = {1, 2, 3};
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]); } }
E. The program compiles and runs fine and the output "Value is 2.0" is printed.
The ________ method copies the sourceArray to the targetArray.
System.arraycopy(sourceArray, 0, targetArray, 0, sourceArray.length);
7. Given the following statement ���� int[ ] list = new int[10];
The array variable list contains a memory address that refers to an array of 10 int values.
Analyze the following code: public class Test { � public static void main(String[] args) { ��� int[] x = new int[5]; ��� for (int i = 0; i < x.length; i++) ����� x[i] = i; ��� System.out.println(x[i]); � } }
The program has a syntax error because i is not defined in the last statement in the main method.
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
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++; } }
D. 2 1
Identify the problems in the following code. public class Test { public static void main(String argv[]) { System.out.println("argv.length is " + argv.length); } }
D. If you run this program without passing any arguments, the program would display argv.length is 0.
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)?
D. low is 5 and high is 4
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.
B. heap
How many elements are in array double[] list = new double[5]?
B. 5
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.
What is the representation of the third element in an array called a?
A. a[2]
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
Which of the following statements is valid?
B. double d[] = new double[30]; C. int[] i = {3, 4, 3, 2};
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);
B. list1 is 2.5 3.1, 3.1, 6.4
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);
B. list1 is 6 5 4 3 2 1
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 + " "); } }
C. The program displays 2.5 3.0 4.0
