Difference between revisions of "SET08112"

From Progzoo
Jump to: navigation, search
(Problem 3 - Who's missing?)
(Problem 3 - Who's missing?)
Line 143: Line 143:
 
       names.add(line);
 
       names.add(line);
 
     }
 
     }
    fh.Close();
+
  }
     fh = new BufferedReader(new FileReader("student.txt"));
+
}
 +
</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&lt;String> names = new ArrayList&lt;String>();
 +
     String line;
 +
    BufferedReader fh
 +
      = new BufferedReader(new FileReader("present.txt"));
 
     while (null!=(line=fh.readLine())){
 
     while (null!=(line=fh.readLine())){
       if (!present.contains(line)) System.out.println(line);
+
      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);
 
     }
 
     }
 
   }
 
   }
 
}
 
}
</prog>
+
</answer>
 
</question>
 
</question>

Revision as of 22:57, 26 January 2011

SET08112 ArrayList Interface Tutorial

In this tutorial you will use the ArrayList and the HashMap or TreeMap to solve some common problems. You will use methods such as:

  • java.util.Collections.sort
  • add
  • get

Problem 1 - Sort a List

The file from http://www.dcs.napier.ac.uk/~cs66/SET08112/tut2/students.txt contains a list of students:

ADAMS, ROBERT
HASTIE, MARTIN
OTHIENO, JUDITH
ANDERSON, ROSS
...

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 java.util.Collections.sort to sort the ArrayList


[Font] [Default] [Show] [Resize] [History] [Profile]

Problem 2 - List Routes

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.

Brando, Marlon 	BSC (HONS) DIGITAL MEDIA F/T
Bridges, Jeff 	BSC (HONS) INTERACTIVE MEDIA DESIGN F/T
Brody, Adrien 	BENG (HONS) COMPUTER SECURITY AND FORENSICS F/T

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 line.split("\t") to get the route
  • Use name.contains(st[1]) to add the route only if it is not already in the ArrayList
  • You do not need to sort before output



[Font] [Default] [Show] [Resize] [History] [Profile]

Problem 3 - Who's missing?

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.

Brody, Adrien
Irons, Jeremy
Spacek, Sissy

How to do this…

  • Create an array list called present
  • Open the file present.txt and add every line to the ArrayList present
  • Open the file student.txt
  • For each line in the file – if that student is not in present print the name.
if (!present.contains(line)) System.out.println(line);


[Font] [Default] [Show] [Resize] [History] [Profile]