Download Chapter 14— Introduction to Collections

Fundamentals of Java
Chapter 14: Introduction to Collections
UNIT 4— LOOKING AHEAD
CHAPTER 14— INTRODUCTION TO COLLECTIONS
EXERCISE 14.3
1.
public static int sum(List<Integer> numbers){
int total = 0;
for (int number : numbers)
total += number;
return total;
}
2.
for (int i = 0; i < list.size(); i++)
System.out.println(list.get(i));
3. The running time for an array list is O(n), whereas the running time for a linked
list is O(n2). An enhanced for loop, which uses an iterator, has a running time of
O(n) for both types of lists:
for (int element : list)
System.out.println(element);
4.
Iterator<Integer> iter = list.iterator();
while (iter.hasNext()){
iter.next();
iter.remove();
}
EXERCISE 14.4
1. a. 30 25 44 55.
b. 30 25 44.
c. 30 25
2.
boolean isPalindrome = true;
Stack<char> stk = new Stack<char>();
for (char ch : source)
stk.push(ch);
int i = 0;
while (! stk.empty())
if (source.chartAt(i) != stk.pop()){
isPalindrome = false;
break;
}
else
i++;
3. a. 138
b. 220
4. Scanner
tokens = new Scanner(source);
while (tokens.hasNext()){
1
Fundamentals of Java
Chapter 14: Introduction to Collections
String token = tokens.next();
System.out.print(token);
if (Character.isDigit(token.charAt(0)))
System.out.println(" : integer");
else
System.out.println(" : operator");
}
EXERCISE 14.5
1. a. 30 25 44 55.
b. 25 44 55.
c. 25 44 55 13
2.
while (! s.empty())
q.add(s.pop());
3. 44 25 30
EXERCISE 14.6
1.
while(! list.isEmpty())
s.add(list.remove(0));
2. 33 67 100 44, in no particular order.
3. int sum = 0;
for (int number : s)
sum += number;
System.out.println(sum);
4.
public static Set<integer> union(Set<integer> s1, Set<integer> s2){
Set<Integer> result = new HashSet<Integer>();
for (int number : s1)
result.add(number);
for (int number : s2)
result.add(number);
return result;
}
EXERCISE 14.7
1.
2.
Map<String, Integer> m = new HashMap<String, Integer>();
for (int i = 0; i < keys.size; i++)
m.put(keys.get(i), values.get(i));
String highestName = "";
int highestGrade = Integer.MIN_VALUE;
Set<String> keys = m.keySet();
for (String currentName : keys){
int currentGrade = m.get(currentName);
if (currentGrade > highestGrade){
highestGrade = currentGrade;
highestName = currentName;
}
2
Fundamentals of Java
Chapter 14: Introduction to Collections
System.out.println(highestName);
3.
int highestGrade = Integer.MIN_VALUE;
Set<String> keys = m.keySet();
for (String currentName : keys){
int currentGrade = m.get(currentName);
if (currentGrade > highestGrade)
highestGrade = currentGrade;
}
Set<String> names = new HashSet<String>();
for (String currentName : keys){
int currentGrade = m.get(currentName);
if (currentGrade == highestGrade)
names.add(currentName);
}
for (String currentName : names){
System.out.println(currentName);
REVIEW QUESTIONS
Fill in the Blank
1. string and list
2. stack
3. queue
4. set
5. array list and linked list
6. array list
7. map
8. iterator
9. List
10. Collection
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