RE: How do I handle exceptions in Java?
I want to learn how to handle exceptions in Java. What are the best practices and could someone give examples of handling common types of exceptions?
In Java, exception handling is performed using the try-catch-finally blocks:
```java
try {
// Code that might throw an exception
} catch (ExceptionType1 e) {
// Handle ExceptionType1
} catch (ExceptionType2 e) {
// Handle ExceptionType2
}
finally {
// Optional block, always executed whether an exception arises or not.
}
```
Here, you replace `ExceptionType1` and `ExceptionType2` with the exceptions you want to catch. The order matters: the Virtual Machine starts with the first `catch` block and tries to match the thrown `Exception` type with the type being caught. General `Exception` types should be last.
Here's a handling 'FileNotFoundException':
```java
try {
File file = new File("nonexistentfile.txt");
FileReader fileReader = new FileReader(file);
} catch (java.io.FileNotFoundException e) {
System.out.println("The file does not exist.");
}
```
Best Practices:
1. **Specificity**: Catch only those exceptions that you can actually handle.
2. **Avoid empty catch blocks**: Catching an exception and doing nothing isn't recommended, as it makes debugging difficult.
3. **Use finally for clean-up**: `finally` block should be used for the clean-up code.
4. **Prefer Unchecked Exceptions**: Unchecked exceptions represent conditions that reflect errors in your program's logic and cannot be recovered from at runtime.
5. **Don’t catch the `Exception` class**: Catching `Exception` will also catch any subclasses — effectively defeating the purpose of your specific catch blocks.
Remember, the purpose of exception handling is to maintain the flow of the program and deal with problems in a controlled manner.
