Using Objects and Methods
What is printed to the console by the statement:
System.out.println("\\a\"");
\a"
Write code that will print out "Yay!" if an integer variable x is a multiple of 3.
if (x % 3 == 0)
System.out.println("Yay!");
Write a setter method for the following instance variable in an unknown class:
private double score;
public void setScore(double s) {
score = s;
}
Write code to swap the elements at indices 2 and 5 in int[] arr.
int temp = arr[2];
arr[2] = arr[5];
arr[5] = temp;
What would the following method call return?
int[] arr = { 13, 11, 6, 2, 13, 4, 3, 10, 9, 8, 4}
sequentialSearch(arr, 3);
6
What are the possible values generated by the call:
Math.random()*3+5
[5.0, 8.0)
Fill in the blank so that the following loop runs exactly 5 times:
for (int i = 0; i < 10; _______) {
/* loop body not shown */
}
i += 2
Write a valid constructor for the following class:
public class Student {
private String name; private int id; private double gpa;
/* rest of class not shown */
}
public Student() {
name = "bob"; id = 123; gpa = 3.2;
}
public Student(String n, int i, double g) {
name = n; id = i, gpa = g;
}
Write code to create an ArrayList of Strings and add "hello" to it.
ArrayList<String> list = new ArrayList<String>();
list.add("hello");
Which elements (in order!) get examined by the following call?
int[] arr = { 1, 3, 5, 8, 9, 11, 14, 15, 17, 20, 21 };
binarySearch(arr, 3);
11, 5, 1, 3
What is returned by the following call:
"basketball".indexOf("ball");
6
What is printed out by the following code?
int count = 1;
while (count <= 10) {
count++;
System.out.print(count + " ");
}
2 3 4 5 6 7 8 9 10 11
public class Dice {
private int currRoll; int numSides;
public Dice(int n) { numSides = n; currRoll = 0; }
public int getRoll() { return currRoll; }
public void roll() { currRoll = Math.random()*numSides+1; }
public void setSides(int n) { numSides = n; }
}
2
Consider list to be an empty ArrayList of Strings. What is output by the following code?
list.add(0, "one");
list.add(0, "two");
list.add(0, "three");
System.out.println(list);
["three", "two", "one"]
What would the following array look like after the 4th pass of insertion sort?
int[] arr = {13, 6, 11, 2, 5, 1, 17, 8, 9, 12}
[ 2, 5, 6, 11, 13, 1, 17, 8, 9, 12 ]
What is returned by the following call:
"hello".substring(3,3)
The empty string
What is printed when x has a value of .8?
if (x > .25) Sys.out.print("second quartile");
else if (x > .5) Sys.out.print("third quartile");
else if (x > .75) Sys.out.print("fourth quartile");
else Sys.out.print("first quartile");
second quartile
What makes a static variable different than an instance variable?
It's a variable shared by the whole class rather than unique to each instance of the class.
Write a method that will return true if a given integer array has all even numbers.
public boolean allEvens(int[] array) {
for (int i = 0; i < array.length; i++) {
if (array[i] % 2 != 0) return false;
}
return true;
}
How many calls to our merge/help method would it take to sort the following array using Merge Sort?
int[] arr = {16, 13, 5, 2, 12, 18, 4, 6, 9, 10, 11, 21}
11
public class Thing {
public Thing(String y, int x) {
/* implementation not shown */
}
}
Thing bob = new Thing("some string", 123);
Use DeMorgan's Law to simplify the following expression:
!(x<3 && y <=2)
x >= 3 || y > 2
QUIET CLASSES
*answers on other sheet*
Write a method that takes in an ArrayList of integers and removes all the multiples of 5 from it.
public void noFives(ArrayList<Integer> nums) {
for (int i = nums.size()-1; i >=0; i--) {
if (nums.get(i) % 5 == 0 ) nums.remove(i);
}
}
MERGE SORT PASSES
int[] arr = {16, 13, 5, 2, 12, 18, 4, 6, 9, 10, 11, 21}
16 5 13 2 12 18 4 6 9 10 11 21
5 13 16 2 12 18 4 6 9 10 11 21
5 13 16 2 12 18 4 6 9 10 11 21
5 13 16 2 12 18 4 6 9 10 11 21
2 5 12 13 16 18 4 6 9 10 11 21
etc.