CS212- Object-Oriented Programming in Java: Lab 8 Solved

Aim: StringTokenizers and two-dimension arrays.

Open Eclipse, set up your private workspace on the H: drive, and create a Java Project for Lab8.
A Java program (Tokens.java) has been provided on the public Z: drive under the folder Lab8. Import this program as well as TextFileInput.java into your Lab8 project in Eclipse:Right click on the src folder under Lab8 in your list of Eclipse projects.
Choose Import, expand General by clicking on the + sign, choose File System
Click on Next, then Browse and go to the Z: drive and select the folder Lab8 and click OK. Click the box next to Tokens.java (the file you want to import) and click Finish.
        Also, import the file twodimension.txt into the Lab8 folder (not the src folder) from the Z: drive.

In Eclipse, double click the file Tokens.java. It should open the file in a tab. Look at line 27 (if you don't see line numbers, right-click in the small column between the scroll bar and the Java source code, and select Show Line Numbers.) The statement myTokens = new StringTokenizer(line,",");
        creates a new StringTokenizer object using a String line and a delimiter (separator) which in the case is the comma (","). The StringTokenizer will contain each of the substrings (tokens) which are separated by the delimiter. So, if line is read from the input file as:

                                "cat,rat,dog,hog,fish,rabbit,horse"

        then myTokens references a StringTokenizer object containing seven strings ("cat","rat","dog",…)

             Observe line 33:

                                animals = new String[myTokens.countTokens()];

        An array is created to store the strings from the StringTokenizer. Notice that the method countTokens returns the number of tokens in the string (in this case, 7).

               Finally, observe line 40:

                                animals[i]=myTokens.nextToken();

        The method nextToken returns the next token stored in the StringTokenizer. The first call, in this case, will return "cat", the next "rat" and so on. Notice that the while loop terminates when the method hasMoreTokens returns false (the last token has been read).

 

With the cursor somewhere inside the tab with the source code, right click and choose Run As Java Application. The program should run, and the output should appear at the bottom in the Console tab.

Run the program.

Now we will use the StringTokenizer in conjunction with the two-dimension array program from Lab 7. The input file in lab 7 had each number for the array on a separate line. A new data file (twodimension8.txt) is in the Lab8 folder on the Z: drive.
Import this file in the the Lab8 project in Eclipse and open it.

 

              The format of the file is:

                   <number of rows>,<number of columns>

  <number>,<number>,…,<number>   . . .

  <number>,<number>,…,<number>

So the input file:                                    Creates the array:

             3,4

  12,45,3,18

  7,65,34,8

  19,56,9,27

 0 1 2 3 

12
45
3
18
7
65
34
8
19
56
9
27
0 

1 

2 

Import the TwoDimArray.java program from the Lab7 Z: drive folder into the src folder for Lab 8.
               Modify the program so that it 

reads the first line of the input file, tokenizes it to get the number of rows and columns,
creates a two-dimension array of integers of the proper dimensions,
reads the rest of the file, tokenizing each line and storing the number in the array (remember to use parseInt).