Software Debugging

• Debugging identifies and fixes errors in programs causing unexpected behavior
• It is a critical and time-intensive part of programming

Debugging Process:

• Examine error symptoms like crashes and error messages to understand the issue
• Identify the root cause by tracing code execution to find the lines creating the problem
• Fix the error by making necessary changes to ensure the code works correctly

Debugging Techniques:

• Understanding the Problem: Fully understand the problem before making changes to ensure effective solutions and save time
• Backtracking: Start from where the problem began and work backward to find out how and why it happened; useful for complex issues

Debugging Tools:

• Debugging tools provide insights into code function, like variable and memory usage, and help save time
• Examples include Chrome DevTools, Testsigma, and dbForger
• Breakpoints and Stepping: Set breakpoints in code where issues might be and use stepping to study variables and data structures
• Breakpoint: a point in the code to temporarily stop execution to inspect the state of its functionality
• Binary Search: Narrow the scope of issues in complex problems by dividing the code into halves and systematically finding the bug
• Rubber Ducking: Explain the problem to someone or something to force critical thinking and discover new insights

More Debugging Techniques:

• Log Analysis: Use log analysis statements in strategic code areas.
• Helps identify issues by understanding code execution flow & variable values at different stages
• Clustering Bugs: Group error reports into related classes. Fixing one bug can resolve others or provide insights
• Take Breaks: Clear your mind to allow for breakthroughs based on a fresh perspective
• Take Notes: Documenting the process and solutions will provide a valuable resource.

Basic Exception Handling:

• Exception: an unexpected or error condition in programming
• Exceptions are not always "bad", and can occur when a value exceeds its storage capacity
• Exception handling: object-oriented techniques to manage or resolve errors like runtime or syntax errors

Error Classes in Java:

• Error Class: Serious errors a program usually cannot recover from, like insufficient memory
• Exception Class: Less serious errors indicating unusual conditions that a program can recover from, like an invalid array subscript
• Error and exception classes descend from the Throwable class, which originates from the Object class
• Throwable class is the superclass for all errors and exceptions in Java

Common Exceptions and Errors:

• IOException: Base class for exceptions thrown while accessing data from files, directories, and streams
• RuntimeException: Only detected during application execution
• ArithmeticException: Raised when a wrong mathematical operation appears in the code
• IndexOutOfBoundsException: Thrown when an index used in arrays, lists, or strings is invalid
• ArrayIndexOutOfBoundsException: Indicates an illegal index (negative, greater than, or equal to the size of the array)
• NoSuchElementException: Indicates that the requested element does not exist
• InputMismatchException: Occurs when the user does not provide the proper type of input/ input is out of range
• VirtualMachineError: Indicates that the Java Virtual Machine is broken or lacks necessary resources
• OutOfMemoryError: Thrown when there is insufficient space to allocate an object
• InternalError: Indicates an unexpected internal Java Virtual Machine error

Try, Catch and Finally Blocks:

• "Try": Programmers "try" a procedure that might cause an error
• If an error condition is detected, it "throws an exception"
• If a block of code processes the error, the block is said to "catch the exception"
• Try Block: where a programmer creates a segment of code in which something might go wrong; acknowledges exceptions

How Try Blocks Work:

• Consists of the "try" keyword and curly braces
• Includes executable statements (including those that might cause exceptions)
• Catch Block: handles exceptions thrown by the try block; automatically/explicitly thrown when a "throw" statement is written

How Catch Blocks Work:

• "Throw" statement: sends an exception outside a method's scope
• Consists of the "catch" keyword and parenthesis filled with an exception type and identifier
• Exception type: type of exception being caught
• If an exception occurs during the try block, it is thrown, the catch block executes, and any statements after the catch also execute
• If no exception occurs, the catch block does not execute and only the statements after the catch do

Finally Block:

• Executes whether or not the preceding try block identifies an Exception
• Used to perform cleanup tasks regardless of Exceptions that occurred/were caught
• Included when there is assurance that the statements will execute before the method is abandoned
• With the finally block, code executes before returning control to the operating system