讲解 TK3163、辅导 java 编程设计
Programming Project TK3163 April 2025
This assignment has 6 activities:
1. Upload and install Jflex and read the manual of JFLex.
I. URL for JFLex installation: https://jflex.de/download.html
II. Once you have downloaded JFlex, unzip the file. Then, open the bin folder and right- click on the jflex.bat file, which is the batch script used on Windows to automate the execution of JFlex.
Then press OK. Now JFlex has been successfully installed and the two environment variables are properly set.
The next step is to understand the lexical structure of the Java programming language. To do this, refer to the manual or documentation related to Java's lexical elements using the following link: https://jflex.de/manual.html.
Specifically, you need to understand how Java code is broken down into tokens such as keywords, identifiers, operators, and literals. From this, choose at least five components of Java's syntax to implement using Jflex (Refer to Question2).
2. Read manual program of JAVA programming language and understand the lexical description by choosing at least 5 components from the lexical JAVA Programming Language, such as statements or expressions,
a. Variable Declaration.
b. Assignment.
c. Selection (if-else)
d. Looping (For)
e. Print
For each of the above-stated components, you must define the lexical rules in a .flex file
using JFlex syntax.
This file should be written in a simple text editor, such as Notepad, and saved with one of the following extensions: .jflex, .jlex, .lex, or .flex. The rules inside the file will define patterns using regular expressions to recognize these components in Java code.
After saving the file, you need to compile it using JFlex via the command prompt. Navigate to the directory where your file is saved (using the cd command in the command prompt).
Then, run your file. This will generate a Java lexer class capable of tokenizing input based on the rules you've defined.
3. Prepare JFlex specification to show regular definition for token described in activity 2.
For this step, you need to prepare the JFlex specification to show the regular definitions for the tokens described in section 2.
Specifically, you need to define regular expressions for Java components like variable declarations, assignments, if-else statements, for loops, and print statements in the .flex file. Each regular expression then will be corresponded to a token in Java code.
After defining these patterns, you must compile the .flex file with JFlex to generate a lexer that can tokenize Java code according to the rules you've defined.
4. Generate a JAVA program using JFlex and show the result of running the program.
After that in this stage you need to generate a Java program using JFlex. To do this, run JFlex from the command prompt to convert the .flex file into a Java lexer. This will generate a .java file, which contains the lexer class.
Once the Java lexer is generated, you can compile and run the Java program to see the results of your lexer in action.
The lexer will process the input based on the regular expressions you've defined in the .flex file and produce the corresponding tokens.
5. Running 4 example programs generated through JFlex generation, 2 example for no error report program and 2 examples with a few errors report and highlight the error.
For this step, you need to create four sample input files. The first two files should contain valid Java code with no lexical errors.
These files will be processed by the lexer, which should correctly tokenize all the valid components, such as keywords, identifiers, operators, and symbols.
The remaining two files should intentionally include lexical errors. These errors can be things like misspelled keywords (e.g., using whle instead of while), invalid symbols (such as @ instead of a valid operator), or incorrect identifiers (like starting an identifier with a number).
After creating these files, you will run the lexer on both the valid and invalid input files. The lexer should successfully tokenize the valid code and highlight the lexical errors in the files with mistakes, providing appropriate error messages for unknown tokens or invalid syntax.
6. For every example, you need to produce a list of lexemes, token types and token.
For each of the example in section 5 you must come out with Lexical Analysis Table.