Java - File Handling - Hands-on

Learning Objectives

• Understand how to perform file operations in Java.
• Implement reading, writing, checking existence, and copying files.
• Parse a CSV file and construct Java objects.

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Exercise 1: Reading a File

Problem Statement

Write a program that reads the contents of a text file and displays it on the console. Handle exceptions for missing or unreadable files.

Instructions:

1. Accept a filename as input.
2. Read and print the file content line by line.
3. Handle FileNotFoundException and IOException appropriately.

Expected Output:

• The content of the file.
• An error message if the file is missing or unreadable.

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Exercise 2: Writing to a File

Problem Statement

Write a program that takes user input and writes it to a text file.

Instructions:

1. Accept a filename and content from the user.
2. Write the content to the specified file.
3. Handle exceptions during the writing process.

Expected Output:

• Confirmation message after successful writing.
• An error message if the operation fails.

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Exercise 3: Checking if a File Exists

Problem Statement

Write a program that checks whether a given file exists or not.

Instructions:

1. Accept a filename as input.
2. Check if the file exists using Java’s File API.
3. Display an appropriate message.

Expected Output:

• A message confirming whether the file exists or not.

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Exercise 4: Copying a File from Source to Destination

Problem Statement

Write a program to copy a file from a source path to a destination path.

Instructions:

1. Accept source and destination file paths as input.
2. Copy the file contents from the source to the destination.
3. Handle exceptions such as FileNotFoundException and IOException.

Expected Output:

• Confirmation that the file was copied successfully.
• An error message if the operation fails.

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Exercise 5: Reading and Parsing a CSV File

Problem Statement

Write a program that reads a CSV file, parses each row, and constructs Java objects from the data.

Instructions:

1. Define a class representing the CSV data (e.g., Person with fields name, age, email).
2. Read the CSV file line by line.
3. Split each line and map it to an object.
4. Handle exceptions for missing or invalid data.

Expected Output:

• List of Java objects constructed from the CSV file.
• An error message if parsing fails.

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Exercise 6: Deleting a File

Problem Statement

Write a program that deletes a specified file and handles potential exceptions.

Instructions:

1. Accept a filename as input.
2. Check if the file exists and delete it.
3. Handle any exceptions that may occur.

Expected Output:

• Confirmation that the file was deleted.
• An error message if deletion fails.

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Exercise 7: Appending Data to a File

Problem Statement

Modify an existing file by appending new data instead of overwriting it.

Instructions:

1. Accept a filename and content from the user.
2. Open the file in append mode and write new data.
3. Handle exceptions during the writing process.

Expected Output:

• Confirmation that the data was appended.
• An error message if the operation fails.

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Exercise 8: Listing Files in a Directory

Problem Statement

Write a program that lists all files in a specified directory.

Instructions:

1. Accept a directory path as input.
2. Display all files and subdirectories inside it.
3. Handle exceptions if the directory does not exist.

Expected Output:

• A list of files and directories in the specified location.
• An error message if the directory is invalid.

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🔗 Related Topics:

• File Handling

• Java NIO