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Key to CSE142 Sample Final handout #34
1. Original List Final List
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(3) (0)
(7, 8) (0, 10)
(5, 4, 3) (0, 6, 10)
(10, 11, 12, 13) (0, 13, 28, 45)
(2, 4, 6, 8, 10) (0, 6, 16, 30, 48)
2. Polymorphism. The output produced is as follows.
sally
sally 1
fred 2
fred
fred 1
fred 2
sally
sally 1
george 2
harold
sally 1
fred 2
3. File Processing. One possible solution appears below.
public static void processData(Scanner input) {
int numNums = 0;
int numEvens = 0;
int sum = 0;
while (input.hasNextInt()) {
int number = input.nextInt();
numNums++;
sum += number;
if (number % 2 == 0)
numEvens++;
}
System.out.println("Total numbers = " + numNums);
System.out.println("Sum of numbers = " + sum);
System.out.println("Total evens = " + numEvens);
System.out.println("Percent evens = " + 100.0 * numEvens/numNums);
}
4. File Processing. One possible solution appears below.
public static void processFile(Scanner input) {
int numLines = 0;
int numChars = 0;
String maxLine = "";
while (input.hasNextLine()) {
String next = input.nextLine();
numChars += next.length();
numLines++;
if (next.length() > maxLine.length())
maxLine = next;
}
System.out.println("Total lines = " + numLines);
System.out.println("Total chars = " + numChars);
System.out.println("Length of longest line = " + maxLine.length());
System.out.println("Longest line = " + maxLine);
}
5. Arrays. One possible solution appears below.
public static int numDuplicates(int[] list) {
int count = 0;
for (int i = 0; i < list.length - 1; i++)
if (list[i] == list[i + 1])
count++;
return count;
}
6. ArrayLists. One possible solution appears below.
public static void replaceStrings(ArrayList list, String target,
String replacement) {
for (int i = 0; i < list.size(); i++) {
String s = (String)list.get(i);
if (s.equals(target))
list.set(i, replacement);
}
}
7. Critters. One possible solution appears below.
public class Robot implements Critter {
private int myMax;
private int myCurrent;
private boolean myGoingEast;
public Robot() {
myGoingEast = true;
myCurrent = 0;
myMax = 1;
}
public char getChar() {
if (myGoingEast)
return '>';
else
return '<';
}
public int getMove() {
int result;
if (myGoingEast)
result = EAST;
else
result = WEST;
myCurrent++;
if (myCurrent == myMax) {
myCurrent = 0;
myMax++;
myGoingEast = !myGoingEast;
}
return result;
}
}
8. Classes. One possible solution appears below.
public class BonusPlan {
private int myMonthly;
private int myOther;
private int myPaid;
public BonusPlan() {
myMonthly = 1;
}
public void rent(boolean free) {
if (!free) {
myPaid++;
if (myPaid == 3) {
myPaid = 0;
myOther++;
}
} else if (myMonthly > 0)
myMonthly--;
else if (myOther > 0)
myOther--;
else
System.out.println("no credits");
}
public int getCredit() {
return myMonthly + myOther;
}
public void endMonth() {
myMonthly = 1;
myPaid = 0;
}
}
9. Arrays. One possible solution appears below.
public void evenOdd() {
int numEvens = 0;
for (int i = 0; i < myLength; i++)
if (myList[i] % 2 == 0) {
int temp = myList[i];
myList[i] = myList[numEvens];
myList[numEvens] = temp;
numEvens++;
}
}
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