Add the changing message in your java code

本文介绍了一种在Java项目中利用CVS进行版本管理的方法,通过在文件头部添加特殊注释$Log:ClassName,v$,可以在提交更改时记录变更原因,从而避免重复书写相同注释的问题。
When you are developing a java project,you maybe want to log the history of the reason of changing your java code.You can write some comment on the head of a java file,but if there are too many files you changed which have the same reason,you need write the same comment in every java file.It's very terror.But if you use cvs to manage your source codes,you can write a line of comment like this:
$Log: ClassName,v $
then,when you commit the source you changed,you can write some message to explain what you did.
Lab 1 - Chapter 2 Chapter 2: Operators and Control Flow (Part 1) Expressions, Operators, and Basic Decisions Course: Java Language Programming Instructor: Ahsan Shehzad Date: September 8, 2025 Practical Session Objective Lab Goal: Give Our Application a Brain 🧠 We will add conditional logic to the MyContactManager project. Using if-else statements, the application will analyze a contact's data and print custom messages. Prerequisites: Java JDK 11 or higher installed. An IDE like IntelliJ IDEA or VS Code ready. Your project files from the previous lab. Final Result Preview: Step-by-Step Guided Exercise Setup: Prepare the Variables Before we can make decisions, we need data. We'll hard-code some variables in our main method to simulate having a single contact. 1. Goal: Define the data for our contact. 2. Instructions: 1. Open your Java project in your IDE. 2. Navigate to the main method in your main application file. 3. Declare and initialize variables to hold a contact's name, age, and friend status. 3. Code Block: Jane Doe is a friend. Categorized as: Adult Match found 1 2 34. Expected Result: The program should compile and run, printing only the "Processing contact..." message for now. Step 1: Implement the Friend Status Check Let's use a simple if-else statement to check the isFriend boolean variable. 1. Goal: Print a different message depending on whether the contact is a friend. 2. Instructions: 1. Below the variable declarations, type if (isFriend) . 2. The code inside the {} following the if will run only if isFriend is true . 3. Add an else block to handle the case where isFriend is false . 3. Code Block: 4. Expected Result: When you run the code, it should now print "Jane Doe is a friend." because isFriend is true . Try changing isFriend to false and see what happens! Step 2: Implement Age-Based Categorization Now, let's use a more complex if-else if-else chain to categorize the contact by age. 1. Goal: Print a message classifying the contact as a "Teenager," "Adult," or "Senior." 2. Instructions: 1. Add a new block of code after the friend-status check. public class MyContactManager { public static void main(String[] args) { // --- Contact Data --- String firstName = "Jane"; String lastName = "Doe"; int age = 32; boolean isFriend = true; System.out.println("Processing contact: " + firstName + " " + lastName); // We will add our logic below this line } } 1 2 3 4 5 6 7 8 9 10 11 12 13 // Inside the main method, after the variables... // --- Logic for Friend Status --- if (isFriend == true) { // You can also just write if (isFriend) System.out.println(firstName + " " + lastName + " is a friend."); } else { System.out.println(firstName + " " + lastName + " is not a friend."); } 1 2 3 4 5 6 7 82. Start with an if to check if age is less than 18. 3. Add an else if to check the next condition (age less than 65). 4. The final else will catch all remaining cases. 3. Code Block: 4. Expected Result: The program will now also print "Categorized as: Adult" since the contact's age (32) falls into the second condition. Review: The Complete Code Let's look at our complete main method with all the logic integrated. 1. Goal: Ensure all the pieces are in the right place. 2. Instructions: Compare your code with the block below to make sure it matches. 3. Code Block: // Inside the main method, after the friend status logic... // --- Logic for Age Categorization --- System.out.print("Categorized as: "); if (age < 18) { System.out.println("Teenager"); } else if (age < 65) { System.out.println("Adult"); } else { System.out.println("Senior"); } 1 2 3 4 5 6 7 8 9 10 11 public class MyContactManager { public static void main(String[] args) { // --- Contact Data --- String firstName = "Jane"; String lastName = "Doe"; int age = 32; boolean isFriend = true; System.out.println("Processing contact: " + firstName + " " + lastName); // --- Logic for Friend Status --- if (isFriend) { System.out.println(firstName + " " + lastName + " is a friend."); } else { System.out.println(firstName + " " + lastName + " is not a friend."); } // --- Logic for Age Categorization --- System.out.print("Categorized as: "); if (age < 18) { 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 204. Expected Result: A clean, readable main method that performs two distinct checks. Final Step: Compile and Run The moment of truth! Let's compile and run our application to see our logic in action. 1. Goal: Verify the final output. 2. Instructions: 1. Save your .java file. 2. Compile and run the program using your IDE's "Run" button or via the command line. 3. Check that the console output matches the expected result exactly. 3. Code Block (Console Output): 4. Expected Result: You have successfully implemented conditional logic! Your program now makes decisions based on the data it has. Challenge Task For Those Who Finish Early... 🚀 If you've completed the lab, try this challenge to test your understanding of the String class. Challenge: Implement a Search Feature 1. Add a new String variable to your main method called searchName and assign it a value (e.g., "Jane" ). 2. Write a new if-else statement that uses the .equals() method to compare searchName with the contact's firstName . 3. If they match, print "Match found" . 4. If they don't, print "No match." System.out.println("Teenager"); } else if (age < 65) { System.out.println("Adult"); } else { System.out.println("Senior"); } } } 21 22 23 24 25 26 27 28 Processing contact: Jane Doe Jane Doe is a friend. Categorized as: Adult 1 2 3Bonus: How could you make the search case-insensitive? (Hint: Look up the equalsIgnoreCase() method in the Java String documentation). 答案是什么
09-22
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