1. CS302 Week 6
Jim Williams

2. This Week P1 Feedback Midterm Exam 1
Lecture: Arrays, Methods and Review

3. P1 Feedback and grades within next couple of days
May request regrade from Grader for 1 week.

4. Midterm Exam 1 What is the location of the exam? 3650 Humanities
1310 Sterling Hall
272 Bascom
Other (due to conflicts)

5. Midterm Exam - Thursday
Bring ID and #2 pencil
Exam seating
directly in front/behind, 1 empty seat to each side
Multiple choice - focus on reading Java
Write on your exam any assumptions
TA led review session - notes on Piazza

6. What will print out and why?65
0x42
Error
int k = 'A';
System.out.println( k);

7. What is the answer? AP? String s1 = "An important programming tool.";
String s2 = s1.substring( 9, 10);
String s4 = new String( "?");
if ( s1.contains( "gram")) {
s4 = s1.substring( 2, 4).trim(); }
char c3 = s1.charAt( s1.indexOf('g') -3);
String answer = (s2 + c3 + s4).toUpperCase();
AP?
api
ANP IM
API

8. What is the output? chars
public static void countChar(char [] chars) {
if ( chars.length > 0 && chars != null)
System.out.println("chars");
else
System.out.println("no chars"); }
public static void main(String[] args) {
char []list = null;
countChar( list);
chars
no chars
compile time error
runtime error

9. What is output? abcde char [] characters = {'a','b','c','d','e'};
public static void main( String [] args) {
char [] characters = {'a','b','c','d','e'};
print( characters);
System.out.println( characters); }
static void print( char []arr) {
arr[2] = 'K';
arr = new char[3];
arr[1] = 'Z’;
abcde
abKde
aZKde
error

10. What prints out? name: Fred name: FRED name: FRED1 name: Fred1
static void change( String name) {
name.toUpperCase();
name = name + "1"; }
public static void main( String [] args) {
String name = "Fred";
change( name);
System.out.println("name: " + name);

11. What are values of x and y?
static int x = 9;
public static void main(String []args) {
int y = 10;
x = methodA( 15, y);
int x = 5;
System.out.println("x="+x+ " y="+y); }
static int methodA( int y, int x) {
y = 1;
return x + y;
x=5 y=10
x=11 y=1
x=11 y=10
x=5 y=15

12. Midterm Exam Today 5 pm to 7 pm Location:

13. What are values of x and y?
static int x;
static int y = 2;
static int methodA( int y) {
x = y + 1;
return x + y; }
public static void main(String []args) {
int x = 5;
y = methodA( x);
System.out.println("x="+x+ " y="+y);
x=5 y=11
x=3 y=2
x=5 y=2
x=3 y=11

14. What kind of methods? max: class nextInt: instance Math.max( 10, 20);
max: instance
nextInt: class
Math.max( 10, 20);
Random randGen = new Random();
randGen.nextInt( 5);
class methods (static)
instances methods (non-static)

15. Instance vs. Class (static) Methods
method definition has “static” modifier
use name of class when calling
Math.max( 10, 20);
Instance (non-static) Methods
method definition does Not have “static” modifier
use instance of class when calling
Random randGen = new Random();
randGen.nextInt( 5);

16. What prints out? true char [] chars1 = {'x','y','z'};
false
char [] chars1 = {'x','y','z'};
char [] chars2 = {'x','y','z'};
System.out.println( chars1 == chars2 );
System.out.println( chars1.equals( chars2));

17. What prints out? true String []pies = new String[3];
false
String []pies = new String[3];
pies[0] = "pizza";
pies[1] = new String("pizza");
pies[2] = "pizza";
System.out.println( pies[1] == pies[2]);
System.out.println( pies[1].equals( pies[2]));

18. What is output? 2 3 hello 2 8 line 5 line 3 line 4 line 8 line error
Scanner input = new Scanner( System.in);
input.nextLine();
int count = 4;
if ( input.hasNextInt())
count = input.nextInt();
else { }
System.out.println( input.nextLine()); 3
hello 2
8 line
5 line
3 line
4 line 2
8 line
error

19. Where is memory allocated?
name: heap
new String("fido"): heap
name: stack
new String("fido"): stack
public static void main( String []args) {
String name;
new String("fido");
name = new String("spot"); }

20. What is print out? two one two main main two one two two two one main
one two two main
static void one() {
System.out.print( "one "); }
static void two(int num) {
System.out.print("two ");
one();
public static void main( String []args) {
two( 3);
System.out.print("main ");

21. What is print out? ling Future lin error
String str = "Falling Off a Cliff "
+ "by Eileen Dover";
System.out.println( str.substring(3,6));
String str2 = "The Future of Robotics " + " by Cy Borg and Anne Droid";
System.out.println(
str2.substring( str2.indexOf('e') + 1,
str2.indexOf('o')).trim());
Strings courtesy of Boy Scouts

22. Can methodB change number?
yes no
maybe
error
public static void main( String []args) {
double number = 5.0;
methodB( number);
System.out.println( number); }

23. Can methodB change list, contents?
list: yes
array contents: yes
list: no
array contents: no
public static void main( String []args) {
double [] list = {5.0,4.3,2.1};
methodB( list );
System.out.println( Arrays.toString(list)); }

24. Can methodB change str, contents?
str: yes
the string: yes
str: no
the string: no
public static void main( String []args) {
String str = "exam today";
methodB( str );
System.out.println( str ); }

25. What is output? String str; str = 7 + 1 * 2 + "6" + 3 + 1;
72631
964
1464
9631
String str;
str = * 2 + "6" ;
System.out.println( str);

26. Good Luck on the Exam!