Java Exceptions
Exceptions can be used to jump out of the current code block, specifying a type of error, which can then be properly dealt with in the code outside of the block.
Throwing exceptions
public void myFunction () throws Exception {
// Your code here
if ( /* Your condition here */ ) {
throw new Exception ("Your error text");
}
}
- To be more specific, you can replace Exception with other kinds of exceptions such as IllegalArgumentException, NumberFormatException, etc.
Try-catch blocks
public void myFunction () {
try {
// Code that might fail (throw exceptions)
} catch (Exception myException) {
// Code to respond if it fails
}
}
- Use this when calling functions that may throw an exception.
Throwing and catching different kinds of exceptions
public void myFunction () {
try {
// Code that might fail (throw exceptions)
} catch (IllegalArgumentException myIAException) {
// Code to respond if it fails
} catch (Exception myException) {
// Code to respond if it fails
}
}
- Use this to react differently to different errors.
- If you catch a general Exception, put that after the more specific Exception catches or they can't be reached.
Stack Trace
catch (Exception myException) {
myException.printStackTrace();
}
- Use this to have the program display (in the console) the line of the error, and sequence of calls that lead to it.
Challenge
Write a function that will throw an IllegalArgumentException if the parameters are in the wrong format. Call that function and have it display a error if it fails. Run the code with invalid parameters to test it.
Quiz
Completed