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| − | ==SET08112 ArrayList Interface Tutorial== | + | ==SET08112 - Algorithms and Data Structure== |
| − | In this tutorial you will use the ArrayList and the HashMap or TreeMap to solve some common problems.
| + | *[[ArrayList Tutorial]] |
| − | You will use methods such as:
| + | *[[Recursion Tutorial]] |
| − | * java.util.Collections.sort
| + | *[[Finite State Machines Tutorial]] and [[Finite State Machine|FSM from lecture]] |
| − | * add
| + | *[[Assessment 2011 Tornado]] |
| − | * get
| + | *[[Recursive Descent Parsers]] |
| − | | + | *[[Tree Tutorial]] |
| − | ==Problem 1 - Sort a List==
| |
| − | <question className="SortStudents" title="Using Sort" copyfile="students.txt">
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| − | The file from http://www.dcs.napier.ac.uk/~cs66/SET08112/tut2/students.txt contains a list of students:
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| − | ADAMS, ROBERT
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| − | HASTIE, MARTIN
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| − | OTHIENO, JUDITH
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| − | ANDERSON, ROSS
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| − | ...
| |
| − | Create a programme SortStudents.java that reads in this file and outputs the students in Alphabetical order.
| |
| − | *You can use an ArrayList to hold the students. | |
| − | *ArrayList<String> names = new ArrayList<String>();
| |
| − | *You can use [http://download.oracle.com/javase/6/docs/api/java/util/Collections.html#sort%28java.util.List%29 java.util.Collections.sort] to sort the ArrayList | |
| − | <hint>
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| − | Add this line after you have filled the ArrayList but before you print it.
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| − | java.util.Collections.sort(names);
| |
| − | </hint>
| |
| − | <prog>
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| − | import java.util.ArrayList;
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| − | import java.io.BufferedReader;
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| − | import java.io.FileReader;
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| − |
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| − | public class SortStudents{
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| − | public static void main(String[]argv) throws Exception{
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| − | ArrayList<String> names = new ArrayList<String>();
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| − | String line;
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| − | BufferedReader fh
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| − | = new BufferedReader(new FileReader("students.txt"));
| |
| − | while (null!=(line=fh.readLine()))
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| − | names.add(line);
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| − | for (String s:names)
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| − | System.out.println(s);
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| − | }
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| − | }
| |
| − | </prog>
| |
| − | <answer>
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| − | import java.util.ArrayList;
| |
| − | import java.io.BufferedReader;
| |
| − | import java.io.FileReader;
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| − |
| |
| − | public class SortStudents{
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| − | public static void main(String[]argv) throws Exception{
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| − | ArrayList<String> names = new ArrayList<String>();
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| − | String line;
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| − | BufferedReader fh
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| − | = new BufferedReader(new FileReader("students.txt"));
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| − | while (null!=(line=fh.readLine()))
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| − | names.add(line);
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| − | java.util.Collections.sort(names);
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| − | for (String s:names)
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| − | System.out.println(s);
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| − | }
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| − | }
| |
| − | </answer>
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| − | </question>
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| − | | |
| − | ==Problem 2 - List Routes==
| |
| − | <question className="SortStudents" title="Using Sort" copyfile="year1.txt">
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| − | The file year1.txt contains a list of all students in year one. Each line contains the name of the student and the name of the route (programme) they follow separated by a tab.
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| − | Brando, Marlon BSC (HONS) DIGITAL MEDIA F/T
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| − | Bridges, Jeff BSC (HONS) INTERACTIVE MEDIA DESIGN F/T
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| − | Brody, Adrien BENG (HONS) COMPUTER SECURITY AND FORENSICS F/T
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| − | | |
| − | Write a program to read in this file and output a list of routes with no duplicates.
| |
| − | You can use a program very similar to the one above – but this time:
| |
| − | *Use <code>line.split("\t")</code> to get the route | |
| − | *Use <code>name.contains(st[1])</code> to add the route '''only''' if it is not already in the ArrayList
| |
| − | *You do not need to sort before output
| |
| − | | |
| − | <prog>
| |
| − | import java.util.ArrayList;
| |
| − | import java.io.BufferedReader;
| |
| − | import java.io.FileReader;
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| − |
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| − | public class SortStudents{
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| − | public static void main(String[]argv) throws Exception{
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| − | ArrayList<String> names = new ArrayList<String>();
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| − | String line;
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| − | BufferedReader fh
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| − | = new BufferedReader(new FileReader("year1.txt"));
| |
| − | while (null!=(line=fh.readLine())){
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| − | String [] st = line.split("\t");
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| − | names.add(st[1]);
| |
| − | }
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| − | for (String s:names)
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| − | System.out.println(s);
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| − | }
| |
| − | }
| |
| − | </prog>
| |
| − | <answer>
| |
| − | import java.util.ArrayList;
| |
| − | import java.io.BufferedReader;
| |
| − | import java.io.FileReader;
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| − |
| |
| − | public class SortStudents{
| |
| − | public static void main(String[]argv) throws Exception{
| |
| − | ArrayList<String> names = new ArrayList<String>();
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| − | String line;
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| − | BufferedReader fh
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| − | = new BufferedReader(new FileReader("year1.txt"));
| |
| − | while (null!=(line=fh.readLine())){
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| − | String [] st = line.split("\t");
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| − | if (!names.contains(st[1]))
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| − | names.add(st[1]);
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| − | }
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| − | for (String s:names)
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| − | System.out.println(s);
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| − | }
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| − | }
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| − | </answer>
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| − | </question>
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| − | ==Problem 3 - Who's missing?==
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| − | <question className="SortStudents" title="Using Sort" copyfile="students.txt present.txt">
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| − | The file present.txt contains those students from students.txt who attended a particular tutorial. We want a list of all those students who were not present.
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| − | Brody, Adrien
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| − | Irons, Jeremy
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| − | Spacek, Sissy
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| − | | |
| − | How to do this…
| |
| − | *Create an array list called present | |
| − | *Open the file present.txt and add every line to the ArrayList present
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| − | *Open the file student.txt
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| − | *For each line in the file – if that student is not in present print the name.
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| − | if (!present.contains(line)) System.out.println(line);
| |
| − | <prog>
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| − | import java.util.ArrayList;
| |
| − | import java.io.BufferedReader;
| |
| − | import java.io.FileReader;
| |
| − |
| |
| − | public class SortStudents{
| |
| − | public static void main(String[]argv) throws Exception{
| |
| − | ArrayList<String> names = new ArrayList<String>();
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| − | String line;
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| − | BufferedReader fh
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| − | = new BufferedReader(new FileReader("present.txt"));
| |
| − | while (null!=(line=fh.readLine())){
| |
| − | names.add(line);
| |
| − | }
| |
| − | }
| |
| − | }
| |
| − | </prog>
| |
| − | <answer>
| |
| − | import java.util.ArrayList;
| |
| − | import java.io.BufferedReader;
| |
| − | import java.io.FileReader;
| |
| − |
| |
| − | public class SortStudents{
| |
| − | public static void main(String[]argv) throws Exception{
| |
| − | ArrayList<String> names = new ArrayList<String>();
| |
| − | String line;
| |
| − | BufferedReader fh
| |
| − | = new BufferedReader(new FileReader("present.txt"));
| |
| − | while (null!=(line=fh.readLine())){
| |
| − | names.add(line);
| |
| − | }
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| − | fh.close();
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| − | fh = new BufferedReader(new FileReader("students.txt"));
| |
| − | while (null!=(line=fh.readLine())){
| |
| − | if (!names.contains(line)) System.out.println(line);
| |
| − | }
| |
| − | }
| |
| − | }
| |
| − | </answer>
| |
| − | </question>
| |
| − | | |
| − | ==Problem 4 - Count Routes==
| |
| − | <question className="CountRoutes" title="Count Routes" copyfile="year1.txt">
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| − | Use the file year1.txt to print a list of all the routes in alphabetical order. We also want a count of how many students are in each route.
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| − | BENG (HONS) COMPUTER NETWORKS AND DISTRIBUTED SYSTEMS F/T 10
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| − | BENG (HONS) COMPUTER SECURITY AND FORENSICS F/T 28
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| − | BENG (HONS) COMPUTING F/T 22
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| − | BENG (HONS) EMBEDDED COMPUTER SYSTEMS F/T 1
| |
| − | ...
| |
| − | | |
| − | How to do this:
| |
| − | *See the section “Use Map to aggregate” from the lecture | |
| − | *You can use two passes to process get the answer.
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| − | **On the first pass run over the list and put the value 0 against every route you encounter.
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| − | **On the second pass use put to add 1 to each route you encounter.
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| − | *It is better to use a single pass:
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| − | **For each route if the key exists then +1 of the value, if the key does not exist then put 1.
| |
| − | <prog>
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| − | import java.util.HashTable;
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| − | import java.io.BufferedReader;
| |
| − | import java.io.FileReader;
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| − |
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| − | public class CountRoutes{
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| − | public static void main(String[]argv) throws Exception{
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| − | HashTable<String,Integer> routes = new HashTable<String,Integer>();
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| − | String line;
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| − | BufferedReader fh
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| − | = new BufferedReader(new FileReader("present.txt"));
| |
| − | while (null!=(line=fh.readLine())){
| |
| − | names.add(line);
| |
| − | }
| |
| − | }
| |
| − | }
| |
| − | </prog>
| |
| − | <answer>
| |
| − | import java.util.ArrayList;
| |
| − | import java.io.BufferedReader;
| |
| − | import java.io.FileReader;
| |
| − |
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| − | public class SortStudents{
| |
| − | public static void main(String[]argv) throws Exception{
| |
| − | ArrayList<String> names = new ArrayList<String>();
| |
| − | String line;
| |
| − | BufferedReader fh
| |
| − | = new BufferedReader(new FileReader("present.txt"));
| |
| − | while (null!=(line=fh.readLine())){
| |
| − | names.add(line);
| |
| − | }
| |
| − | fh.close();
| |
| − | fh = new BufferedReader(new FileReader("students.txt"));
| |
| − | while (null!=(line=fh.readLine())){
| |
| − | if (!names.contains(line)) System.out.println(line);
| |
| − | }
| |
| − | }
| |
| − | }
| |
| − | </answer>
| |
| − | </question>
| |
